Interpretation of Diagnostic Tests
8th Edition
© 2007 Lippincott Williams & Wilkins
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1
Introduction to Normal Values (Reference Ranges)
General Principles
The purpose of all testing (laboratory, radiologic, ECG, etc.) is to reduce clinical uncertainty. The degree of reduction varies with the test characteristics and clinical situation. Modern medicine has superseded Voltaire’s dictum that “the art of medicine consists of amusing the patient while nature cures the disease.”
Many clinicians are still largely unaware of the reasoning process that they pursue in seeking a diagnosis. They tend to follow an empirical path that was previously successful or was learned during early training periods by observing their mentors during clinical rounds without appreciating the rationale for selecting, ordering, and interpreting laboratory tests. This is often absorbed in a subliminal, informal, or rote fashion. The need to control health care costs and many recent studies on laboratory test use have emphasized the need for a selective approach.
Some important principles in using laboratory (and all other) tests are as follows:
  • Under the best of circumstances, no test is perfect (e.g., 100% sensitivity, specificity, predictive value). In any specific case, the results may be misleading. The most sensitive tests are best used to rule out a suspected disease so that the number of false-negative tests is minimal; thus a negative test tends to exclude the disease. The most specific tests are best used to confirm or exclude a suspected disease and minimize the number of false-positive results. Sensitivity and specificity may be markedly altered by the coexistence of other disorders or complications or sequelae of the primary disease. (See Table 1-1.)
  • Choice of tests should be based on the prior probability of the diagnosis being sought, which affects the predictive value of the test. This prior probability is determined by the history, physical examination, and prevalence of the suspected disorder (in that community at that time), which is why history and physical examination should precede ordering tests. The clinician need not know the exact prior probability of the disease. It is usually sufficient to estimate this as high, intermediate, or low. Moderate errors in estimating prior probability have only relatively limited effects on interpretation of the tests. If the prior prevalence is high, a positive result tends to confirm the presence of the disease but an unexpected negative result is not very useful in ruling out the disease. Conversely, when the prior prevalence is low, a normal result tends to rule out the disease but an unexpected positive result is not very useful in confirming the disease. If the prior probability
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    of a disease is high, only a negative test on a very sensitive test can lower the probability sufficiently to rule out that disease. (See Tables 1-2 and 1-3.)
    Table 1-1. Definition of Terms
    Test Result Disease Present Disease Absent
    Positive A (true-positive) B (false-positive)
    Negative C (false-negative) D (true-negative)
    Total    
    Sensitivity = A/(A + C).
    Specificity = D/(B + D).
    Positive predictive value (PPV) = A/(A + B).
    Negative predictive value (NPV) = D/(C + D).
    Table 1-2. Assuming a Low Prior Probability (10%) (in 1,000 Tests, Disease is Present in 100 and Absent in 900)
    Prevalence = (90 + 10)/(90 + 180 + 10 + 720) or (100/1,000) = 10%
    Test Result Disease Present Disease Absent
    Positive 90 (true-positive) 180 (false-positive)
    Negative 10 (false-negative) 720 (true-negative)
    Total 100 900
    With a test of high sensitivity (e.g., 90%), the positive predictive value (probability that those with a positive test have the disease) is only 33% [90/(90 + 180)]. In contrast, the negative predictive value (% of those with a negative test who do not have the disease) [720/(10 + 720)] = 99%. Thus a negative test indicates 99% probability of no disease. The specificity = 720/(180 + 720) = 80%.
    Table 1-3. Assuming a High (90%) Prior Probability (in 1,000 Tests, Disease is Present in 900 and Absent in 100)
    Prevalence = (810 + 90)/(810 + 20 + 90 + 80) or (90/1,000) = 90%
    Test Result Disease Present Disease Absent
    Positive 810 (true-positive) (A)   20 (false-positive) (B)
    Negative   90 (false-negative) (C)   80 (true-negative) (D)
    Total 900 100
    With a test of high sensitivity (e.g., 90%), the positive predictive value (probability that those with a positive test have the disease) is 98% [810/(810 + 20)], indicating near certainty that disease is present. In contrast, the negative predictive value (% of those with a negative test who do not have the disease) is 47% [80/(90 + 80)]. Thus a negative test (probability of no disease) indicates that the patient still has a fairly high possibility of having the disease (47%). The specificity = 80/(20 + 80) = 80%.
  • In most laboratory measurements, the combination of short-term physiologic variation and analytic error is sufficient to render the interpretation of single determinations difficult when the concentrations are in the borderline range. For example, the individual’s coefficient of variation (CV) for cortisone over 7 days is 21% and for C-reactive protein (CRP) for 1 to 6 months is 57%, whereas the CV for sodium is 0.6% and for calcium is 1.8%. Any particular laboratory result may be incorrect for many reasons regardless of the high quality of the laboratory; all unexpected or suspicious results should be rechecked. If indicated, a new specimen sample should be submitted with careful confirmation of patient identification,
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    prompt delivery to the laboratory, and immediate processing. In some circumstances, confirmation of test results at another laboratory may be appropriate.
  • Strive to avoid random analytic error in an analytic method including changes in temperature, volume of reagent or sample, and so on.1 Imprecision is measured by calculating the mean, standard deviation (SD), and CV. Imprecision does not include preanalytic variables (e.g., specimen collection, transport, and receipt in laboratory as well as diet; time of eating; menstrual, circadian, and seasonal rhythms; posture, exercise, and mobilization; recent transfusion; environmental temperature, altitude, and geography, etc.) or postanalytic variables (e.g., transcription and telephone reports, absent reference ranges, etc.). Preanalytic errors constitute 31% to 75% of all laboratory errors, postanalytic errors constitute 9% to 30% of all laboratory errors, and analytic errors (e.g., subjective interpretation, contamination, interferences, cross-reactions, methodology) constitute 13% to 31% of all laboratory errors.2
    It should be remembered that imprecision depends on the concentration of the analyte.
    The following illustrations may be useful:
    Serum cholesterol has decreased from 250 mg/dL to 220 mg/dL during 6 months. Assuming a zero analytic bias and CV of 3% and a 95% confidence interval, at a 250 mg/dL concentration, the cholesterol concentration is between 235 and 265 mg/dL. At the concentration of 220 mg/dL, the 95% confidence interval is 207 to 233 mg/dL. Since the confidence intervals do not overlap, this is a true analytic change. However, the physiologic variation is approximately 6%. Using the formula,3 the 95% confidence interval for these values of 250 mg/dL (216–284) and 220 mg/dL (186–254) results in overlapping values that are not significantly different.
    A test with high sensitivity (i.e., few false-negatives) is used when there are significant consequences to missing the diagnosis. A test with high specificity is used (i.e., few false-positives) to avoid labeling a patient who does not have the disease. Sensitivity and specificity can be calculated at different cutoff points to generate a receiver-operating-characteristic (ROC) curve. Ideally, a test will be highly sensitive through the whole range of specificity. The most useful tests show the largest area under the ROC curve.
    The likelihood ratio (LR) is independent of the prevalence (unlike the predictive value) and helps to assess the diagnostic benefit of a positive or negative test. It is a ratio of the probability that the test result is positive in a patient who has the disease compared with the probability that the test result is positive in a person who does not have the disease. LR = 1 indicates equal likelihood of disease presence or absence; higher values mean disease is that many times more likely to be present than absent, and lower values mean the opposite.
    LR shows the magnitude and direction of a change from pretest to posttest probability for which a nomogram or formula4 can be used:
    Posttest probability = pretest probability × LR/[1 + pretest probability × (LR - 1)]
    A change of 1 to 2 from pretest to posttest probability makes little difference, but a change in LR of <0.1 or >10 from pretest to posttest probability may be diagnostic.
  • Based on the statistical definition of “normal” as 95% range of values, 5% of independent tests will be outside this normal range in the absence of disease. If 12 tests are performed, at least one abnormal result will occur in 46% of normal persons; for 20 tests, 64% of normal persons will have at least one abnormal result.
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    The greater the degree of abnormality of the test result, the more likely that a confirmed abnormality is significant or represents a real disorder. Most slightly abnormal results are due to preanalytic factors.
  • Tables of reference values represent statistical data for 95% of the population; values outside these ranges do not necessarily represent disease. Results may still be within the reference range but be elevated above the patient’s baseline, which is why serial testing is important in a number of conditions. For example, in acute myocardial infarction, the increase in serum total creatine kinase (CK) may be abnormal for that patient although the value may be within “normal” range.
  • An individual’s test values when performed in a good laboratory tend to remain fairly constant over a period of years when performed with comparable technology; comparison of results with previous values obtained when the patient was not ill (if available) are often a better reference value than “normal” ranges.
  • Multiple test abnormalities are more likely to be significant than single test abnormalities. When two or more tests for the same disorder are positive, the results reinforce the diagnosis; however, when only one test is positive and the other is not positive, the strength of the interpretation is diluted. Similarly, ratios of various analytes are often useful (e.g., BUN:creatinine, albumin:globulin, chloride: phosphate, liver function tests), and the clinician may find useful clues in these.
  • The degree of abnormality (signal strength) is useful. Thus a value increased ten times the upper reference range is much more likely to be clinically significant than one that is only slightly increased.
  • Characteristic laboratory test profiles that are described in the literature and in this book represent the full-blown picture of the well-developed or far advanced case, but all abnormal tests may be present simultaneously in only a small fraction (e.g., one-third) of patients with that condition. Even when a test profile (combination of tests) is characteristic of a particular disorder, other disorders or groups of conditions may produce exactly the same combination of laboratory test changes.
  • Excessive repetition of tests is wasteful, and the excess burden increases the possibility of laboratory errors. Appropriate intervals between tests should be dictated by the patient’s clinical condition.
  • Tests should be performed only if they will alter the patient’s diagnosis, prognosis, treatment, or management. Incorrect test values or isolated individual variation in results may cause Ulysses syndrome and result in loss of time, money, and peace of mind.
  • Clerical errors are far more likely to cause incorrect results than are technical errors. Greatest care should be taken to completely and properly label and identify every specimen, which should always be accompanied by a test requisition form. Busy hospital laboratories receive inordinate numbers of unlabeled, unidentified specimens each day, which are useless, burdensome, and sometimes dangerous.
  • Reference ranges vary from one laboratory to another; the user should know what these ranges are for each laboratory used and should also be aware of variations due to age, sex, race, size, physiologic status (e.g., pregnancy, lactation, diet, diurnal variation) that may apply to the particular patient. These “normal” ranges represent collected statistical data rather than classification of patients as having disease or being healthy. This is best illustrated in the use of multitest chemical profiles for screening persons known to be free of disease. The probability of any given test being abnormal is about 2% to 5%, and the probability of disease if a screening test is abnormal is generally low (0% to 15%). The frequency of abnormal single tests is 1.5% (albumin) to 5.9% (glucose) and up to 16.6% for sodium. Based on statistical expectations, when a panel of eight tests is performed in a multiphasic health program, 25% of the patients have one or more abnormal results; when the panel includes 20 tests, 55% have one or more test abnormalities.5
  • The effect of drugs on laboratory test values must never be overlooked. The clinician should always be aware of what drugs the patient has been taking, including over-the-counter medications, vitamins, iron, and so on. These effects may produce false-negative as well as false-positive results; for example, vitamin C may produce a false-negative test for occult blood in the stool. Complementary and alternative medicines may cause increased serum bilirubin and liver enzymes (e.g., kava-kava,
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    chaparral, comfrey, germander). Unexpected high digoxin levels may be due to interference by Chan Su, Dan Shen, or ginseng. Reduced cyclosporine levels are reported due to use of St. John’s wort. Contamination by heavy metals (e.g., arsenic, lead, mercury) in many Chinese medicines may cause toxicity.
    Table 1-4. Reference Ranges for Complete Blood Cell Count at Various Ages
    Age RBC (× 106/cu mm) Hb (g/dL) Hct (%) MCV (fL) MCH (pg) RDW (%)
    Newborn 4.1–6.7 15.0–24.0 44–70 102–115 33–39 13.0–18.0
    1–23 mos 3.8–5.4 10.5–14.0 32–42   72–88 24–30 11.5–16.0
    2–9 yrs 4.0–5.3 11.5–14.5 33–43   76–90 25–31 11.5–15.0  
    10–17 yrs
       Males 4.2–5.6 12.5–16.1 36–47   78–95 26–32 11.5–14.0
       Females 4.1–5.3 12.0–15.0 35–45   78–95 26–32 11.5–14.0  
    >18 yrs
       Males 4.7–6.0 13.5–18.0 42–52   78–100 27–31 11.5–14.0
       Females 4.2–5.4 12.5–16.0 37–47   78–100 27–31 11.5–14.0
    Mean platelet volume = 6.0–9.5 fL for all age groups. Platelets = 150,000–450,000/cu mm for all age groups. Mean corpuscular hemoglobin concentration = 32–36 gm/dL for all age groups.
    Source: Clinical Laboratories of Children’s Hospital of Buffalo.
  • The reader must be aware of the effect of artifacts causing spurious values and of factitious disorders especially in the face of discrepant laboratory results.
  • Negative laboratory values (or any other type of tests) do not necessarily rule out a clinical diagnosis.
Footnotes
1
Grenache DG. Imprecision and physiological variation. Impact on uncertainty of clinical laboratory results. Clin Lab News March 2004:12.
2
Matlow AG, Berte LM. Sources of error in laboratory medicine. Lab Med 2004;35:331.
3Standard error of the mean estimate: N = (1.96 × [CVA2 + CV12]0.5 divided by D2) where:
  • 1.96 is the 95% probability level
  • CVA = analytic imprecision at homeostatic set point
  • CV1 = individual’s biologic variation
  • D = % deviation from the “acceptable” homeostatic set point
5
Friedman GD, Goldberg M, Ahuja JN, et al. Biochemical screening tests: effect of panel size on medical care. Arch Int Med 1972;129:91.
6
Greer JP, et al., eds. Wintrobe’s Clinical Hematology. 11th ed. Philadelphia: Lippincott Williams & Wilkins; 2004.
7
McMillan JA, et al., eds. Oski’s Pediatrics. 4th ed. Philadelphia: Lippincott Williams & Wilkins; 2006.
8
Quest Diagnostics. Chantilly, VA: Nichols Institute Directory of Services; 2003.
Typical Reference Values
These are typical references values. Readers are referred to these and other sources and especially their own laboratories for more detailed data.6,7,8
Hematology Reference Values
Complete blood count (CBC) See Tables 1-4, 1-5, 1-6, and 1-7
Carboxyhemoglobin (WB)
   Smoker 2.1%–4.2%
   Nonsmoker <2.3%
Erythrocyte sedimentation rate (ESR) (WB)
   Westergren
      Males 0–15 mm/1 hr
      Females 0–25 mm/1 hr
   Wintrobe
      Males 0–10 mm/1 hr
      Females 0–15 mm/1 hr
      Neonate/child 3–13 mm/1 hr
      Newborn 0–4 mm/1 hr
Erythropoietin (S) 3–20 mIU/L
Ferritin (S)
   Newborns 25–200 ng/mL
   1 month 200–600 ng/mL
   2–5 months 50–200 ng/mL
   6 months–15 years 7–140 ng/mL
   Adult males 30–300 ng/mL
   Adult females 10–200 ng/mL
   Borderline (males or females) 10–20 ng/mL
   Iron excess >400 ng/mL
Folate (RBCs) >280 ng/mL
Folate (S) 3–25 ng/mL
Free erythrocyte protoporphyrin (FEP) 16–36 μg/dL packed RBCs
Glucose-6-phosphate dehydrogenase (RBCs) 6.1–9.3 IU/g Hb
Haptoglobins (S) Genetic absence in 1% of population
   Newborns Absent in 90%; 10 mg/dL in 10%
   Age 1–6 months Gradual increase to 30 mg/dL
   6 months–17 years 40–180 mg/dL
   Adults 16–199 mg/dL
Hematocrit (WB) 41%–53%
Hemoglobin (P) <1–5 mg/dL
Hemoglobin (WB) 13.5–17.5 g/dL
Hemoglobin electrophoresis (WB)
   HbA (α2β2)
      0–30 days 10%–40%
      6 months to adult 95%–98%
   HbA2 (α2δ2)
      <1 year <2%
      1 year to adult 1.5%–3.5%
   HbF (α2γ2) <2%
   Other Hb variants None
Iron (liver tissue) 530–900 μg/g dry weight
Iron (S)
Newborn 100–250 μg/dL
   Infant 40–100 μg/dL
   Child 50–120 μg/dL
   Adults
      Male 65–175 μg/dL
      Female 50–170 μg/dL
Iron-binding capacity (IBC) 224–428 μg/dL
   % saturation 15%–50%
Leukocyte alkaline phosphatase (LAP) score 40–100
Lysozyme (muramidase) (S) 7.0–15.0 μg/mL
Marrow sideroblasts ≥30% of normoblasts
Methemoglobin (WB) <1% of total Hb
Osmotic fragility of RBCs Increased if hemolysis occurs in >0.5% NaCl
Decreased if incomplete in 0.30% NaCl
Pyruvate kinase (RBCs) 13–17 IU/g Hb
RBC survival time (51Cr) Half-life: 25–35 days
Reticulocyte count (WB) 0.5–2.5% of RBCs
Reticulocyte hemoglobin content, reticulocyte index, mean volume, parameter, hemoglobin.
Immature reticulocyte fraction.		 See Chapter 11
Ringed sideroblasts None
Transferrin (S) 240–480 mg/dL
Transferrin receptor (S) 0.57–2.8 μg/L
Transferrin saturation
Males Females
14.2%–58.4% 15.2%–49.3%
TfR-F index (sTfR:log serum ferritin)
Males Females
0.45–1.88 0.46–13.29
Unsaturated vitamin B12-binding capacity 870–1,800 pg/mL
Vitamin B12 (S) 190–900 ng/L
Volume (mL/kg body weight)
   Blood
   RBC
   Plasma
Males Females
75 67
30 24
44 43
RBCs, red blood cells; S, serum; WB, white blood.
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Table 1-5. Reference Ranges for White Blood Cell Count (WBC) at Various Ages (Differential Count in Absolute Numbers)
Age WBC (×1,000/cu mm) Total Neutrophils* Segs Bands Lymphs Monos Eos Baso
Newborn 9.1–34.0 6.0–23.5 6.0–20.0 <3.5 2.5–10.5 <3.5 <2.0 <0.4
1–23 mos 6.0–14.0 1.1–6.6 1.0–6.0 <1.0 1.8–9.0 <1.0 <0.7 <0.1
2–9 yrs 4.0–12.0 1.4–6.6 1.2–6.0 <1.0 1.0–5.5 <1.0 <0.7 <0.1
10–17 yrs 4.0–10.5 1.5–6.6 1.3–6.0 <1.0 1.0–3.5 <1.0 <0.7 <0.1
>18 yrs 4.0–10.5 1.5–6.6 1.3–6.0 <1.0 1.5–3.5 <1.0 <0.7 <0.1
Segs = segmented neutrophils; Bands = band neutrophils; Lymphs = lymphocytes; Monos = monocytes; Eos = eosinophils; Baso = basophils.
*Total Neutrophils = Segs + Bands.
Source: Clinical Laboratories of Children’s Hospital of Buffalo.
Table 1-6. Reference Ranges for Blood Cell Count at Various Fetal Ages
  Age (wks)
   18–20 21–22 23–25 25–30
RBC (×106/cu mm) 2.35–2.95 2.70–3.22 2.80–3.32 3.20–3.84
Hb (gm/dL) 10.7–12.3 11.4–13.2 12.1–12.7 12.2–14.5
Hct (%) 33–39 35–41 36–41 38–45
MCV (fL) 125–142 123–136 119–132 112–124
WBC (×1,000/cu mm) 3.6–5.0 3.4–5.0 3.3–4.6 3.5–5.2
Platelets (×1,000/cu mm) 208–277 203–312 217–301 216–290
RBC = red blood cell count; Hb = hemoglobin; Hct = hematocrit; MCV = mean corpuscular volume; WBC = white blood cell count.
Source: Daffos F. Fetal blood sampling. In: Harrison WR, Globus MS, Filly RA, eds. The unborn patient, 2nd ed. Philadelphia: WB Saunders, 1991:79.
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Table 1-7. Pediatric Reference Ranges for Lymphocyte Counts
Lymphocytes Age (mos)
0–6 6–12 12–18   18–24 24–30 30–36 >36
Total % 62–72 60–69 56–63   52–29 45–57 38–53 22–69
Total absolute 5,395–7,211 5,284–6,714 4,943–5,943   4,431–5,508 3,855–5,248 3,315–5,058 1,622–5,370
CD4 % 5,057 4,955 4,651   4,248 3,846 3,344 2,757
CD4 absolute 2,780–3,908 2,630–3,499 2,307–2,864   1,919–2,472 1,538–2,213 1,216–2,009 562–2,692
CD8 % ___________________________________ 8–31 ___________________________________ 14–34
CD8 absolute ___________________________________ 351–2,479 ___________________________________ 331–1,445
CD2 % ___________________________________ 55–88 ___________________________________ 65–84
CD2 absolute 3,929–5,275 3,806–4,881 3,516–3,868   3,101–3,868 2,640–3,639 2,236–3,463 1,230–4,074
CD3 % ___________________________________ 55–82 ___________________________________ 55–82
CD3 absolute 3,505–5,009 3,409–4,575 3,156–3,899   2,766–3,508 2,324–3,295 1,923–3,141 1,072–3,890
CD19 % ___________________________________ 11–45 ___________________________________ 9–29
CD19 absolute ___________________________________ 4,32–3,345 ___________________________________ 200–1,259
Helper-suppressor ratio ___________________________________ 1.2–6.2 ___________________________________ 0.98–3.24
Source: Riley Hospital for Children, Indiana University Medical Center, 1992.
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Blood Coagulation Tests—Reference Values
Activated clotting time (WB) 70–180 sec
Activated protein C resistance (factor V Leiden) (P) Ratio >2.1
Alpha2-antiplasmin (P) 80%–130%
Antiphospholipid-antibody panel  
   Partial thromboplastin time—lupus anticoagulant screen (P) Negative
   Dilute Russell viper venom time (dRVVT) (P) Negative
   Platelet-neutralization (P) Negative
   Anticardiolipin antibody IgG or 0–15 U
      IgM (S)  
Antithrombin III (P)
      Immunologic 22–39 mg/dL
   Functional 80%–130%
Anti-Xa assay (heparin) (P)  
      Unfractionated 0.3–0.7 IU/mL
   Low-molecular-weight 0.5–1.0 IU/mL
   Danaparoid 0.5–0.8 IU/mL
Bleeding time (Simplate) 2–9.5 minutes
Clot retraction, qualitative (WB) Begins in 1/2–1 hr;
50%–100% in 2 hr
Cryofibrinogen (P) Negative
D-dimer (P) <0.5 μ/mL
Coagulation factor assay (P) Activity Plasma levels
   I (fibrinogen)   150–400 mg/dL
   II (prothrombin) 60%–140%* 100 μg/mL
   V 60%–140%*† 10 μg/mL
   VII 60%–140%*† 0.5 μg/mL
   VIII (AHG) 50%–200%* 0.1 μg/mL
   IX 60%–140%*† 5 μg/mL
   X 60%–140%*† 10 μg/mL
   XI 60%–140%* 5 μg/mL
   XII 60%–140%* 30 μg/mL
   XIII screen No deficiency detected
Fibrin and fibrinogen degradation products (P) <2.5 μ/mL
Partial thromboplastin time, activated (aPTT) (P) 25–38 sec
Plasminogen (P)
   Antigenic 8–14 mg/dL
   Functional 80%–130%
Platelet aggregation >65% aggregation in response to ADP, epinephrine, collagen, ristocetin, arachidonic acid
Platelet count 150,000–350,000/μL
Protein C, total antigen or functional (P) 70%–140%
Protein S, total or free antigen or functional (P) 70%–140%
Prothrombin-gene mutation G20210A Absent
Prothrombin time (P) 11–13 sec
Reptilase time (P) 16–24 sec
Thrombin time (P) 16–24 sec
Ristocetin cofactor (functional vWF) (P)  
   Blood Group O 75% mean of normal
   Blood Group A 105% mean of normal
   Blood Group B 115% mean of normal
   Blood Group AB 125% mean of normal
von Willebrand factor (factor VIII:R) antigen (P)  
   Blood Group O 75% mean of normal
   Blood Group A 105% mean of normal
   Blood Group B 115% mean of normal
   Blood Group AB 125% mean of normal
von Willebrand factor multimers (P) Normal distribution
Coagulation time (Lee-White) 6–17 minutes (glass tubes)
19–60 minutes (siliconized tubes)
Euglobulin lysis No lysis in 2 hours
Fibrinogen split products Negative at >1:4 dilution
Positive at >1:8 dilution
Fibrinolysins (WB) No clot lysis in 24 hours
Platelet antibody (S) Negative
P, plasma; S, serum; WB, whole blood.
*Infants may not reach adult level until age 6 months.
†Increases with age in elderly.
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Blood Chemistries—Reference Values
These values will vary, depending on the individual laboratory as well as the methods, reagents, and instruments used. Each clinician should compare the applicability of these data to his or her own situation.
Acetoacetate (P) <1 mg/dL
Acetone (S, P) 0.3–2.0 mg/dL
Aldolase (S)
   Neonate <32 U/L
   Child <16 U/L
   Adults 1.0–8.0 U/L
Alkaline phosphatase (S) 30–120 U/L
Alpha1 antitrypsin (S) 85–213 mg/dL
Alpha-fetoprotein (S) <15 ng/mL
Ammonia (P) 19–60 μg/dL
      Newborn at term or premature <50 U/L
Amylase, total (S) +
Angiotensin-converting enzyme (ACE) (S) <40 U/L
Anion gap (calculated) 8–16 or 10–20 mEq/L (See Chapter 12)
Apolipoprotein A-1 (S) 120–240 mg/dL
Apolipoprotein B (S) 50–160 mg/dL
Apolipoprotein B/apolipoprotein A1 ratio 0.35–98
Base, excess  
   Newborns -10 to -2 mEq/L
   Infant -7 to -1 mEq/L
   Child -4 to +2 mEq/L
   Adult -3 to +3 mEq/L
Beta-hydroxybutyrate (P) <3 mg/dL
Bicarbonate (arterial WB)
   <2 years 20–25 mEq/L
   Adult 22–28 mEq/L
Bilirubin9 (S)  
Total
      Cord
      <1 day
      1–2 days
      3–5 days
      >1 month
      Adult
Term Preterm
<2.0 mg/dL <2.0 mg/dL
<6.0 mg/dL <8.0 mg/dL
<8.0 mg/dL <12.0 mg/dL
<12.0 mg/dL <16.0 mg/dL
<1.0 mg/dL <2.0 mg/dL
≤1.0 mg/dL
   Direct 1 month to adult 0.1–0.3 mg/dL
Brain-type natriuretic peptide BNP = 80–100 pg/mL.
      (BNP) (S) NT-proBNP = 125 pg/mL for age <75 years; 450 pg/mL for age >75 years
Calcium, total (S)  
   <1 week 7.0–12.0 mg/dL
   Child 8.0–11.0 mg/dL
   Adult 9.0–10.5 mg/dL
Calcium, ionized (WB) 3.0–4.5 mg/dL
Carbon dioxide  
   CO2 content (P) 21–30 mEq/L
   pCO2 (partial pressure) (arterial WB) 35–45 mm Hg
Carbon monoxide (WB) See Chapter 17
Ceruloplasmin (S) 27–37 mg/dL
Chloride (S) 98–106 (mEq/L)
Cholesterol (P)  
   Total cholesterol (adult)  
      Desirable <200 mg/dL
      Borderline high 200–239 mg/dL
      High ≥240 mg/dL
   Total cholesterol (<19 years old)  
      Desirable <170 mg/dL
      Borderline high 170–199 mg/dL
      High ≥200 mg/dL
   High-density lipoprotein (HDL) cholesterol  
      High ≥60 mg/dL
      Low <40 mg/dL
   Low-density lipoprotein (LDL) cholesterol  
      Optimal <100 mg/dL
      Near normal 100–129 mg/dL
      Borderline high 130–159 mg/dL
      High 160–189 mg/dL
      Very high ≥190 mg/dL
Cholinesterase (S) 5–12. U/mL (See Chapter 17)
Complement (S)
   Total complement, CH50 75–160 U/mL
   C3 <3 months 53–131 mg/dL
   C3, 3 months–1 year 62–180 mg/dL
   C3, 1–10 years 77–195 mg/dL
   C3, adult 83–177 mg/dL
   Factor B (C3 proactivator) 17–42 mg/dL
   C4 cord blood 6.6–23 mg/dL
   C4 <3 months 7–28 mg/dL
   C4 3 months–1 year 7–42 mg/dL
   C4 1–10 years 9.2–40 mg/dL
   C4 adult 15–45 mg/dL
Copper (S) 70–140 μg/dL
Copper (U) 3–35 μg/dL
Creatine kinase (CK), total (S)  
   Males 60–400 U/L
   Females 40–150 U/L
Creatine kinase isoenzyme (S) (See Chapter 5)
CK-MB (<5% of total) or <5 ng/mL CK-BB (trace) CK-MM (94%–96% of total)
   Male 24–195 IU/L
   Female 24–170 IU/L
MB index (CK-MB/total CK) (calculated) <2.5
Creatinine (S)  
   Newborn 0.3–1.0 mg/dL
   Infant 0.2–0.4 mg/dL
   Child 0.3–0.7 mg/dL
   Adolescent 0.5–1.0 mg/dL
   Adult <1.5 mg/dL
Cryoglobulins (P) Negative
Gamma-glutamyl transferase (GGT) (S) 6–19 U/L
Glucose (fasting) 60–100 mg/dL (depends on method) (See Chapter 13)
Homocysteine, total (P) 4–12 μmol/L
Isocitrate dehydrogenase (ICD) (S) 3–85 U/L
Lactate (venous P) 5–15 mg/dL
Lactate dehydrogenase (LDH) (S)  
   Newborn 160–1,500 U/L
   Infant 150–360 U/L
   Child 150–300 U/L
   Adult 100–190 U/L
Lactate dehydrogenase isoenzymes (S) (See Chapter 3)  
   LD-1 14%–26%
   LD-2 29%–39%
   LD-3 20%–26%
   LD-4   8%–16%
   LD-5   6%–16%
Lead (S) (See Chapter 17)  
   Adults <10 μg/dL
   ≤15 years <9 μg/dL
Leptin (<15% body fat in men, <25% in women) 1–16 μg/L
Leucine aminopeptidase (LAP) (S) 1.1–3.4 U/mL
Lipase (S) 0–160 U/L
Magnesium (S) 1.8–3.0 mg/dL
Myoglobin (S)  
   Male 19–92 μg/L
   Female 12–76 μg/L
5′-Nucleotidase (S) 0–11 U/L
Osmolality (P) 285–295 mOsm/kg
Osmolality (U) 300–900 mOsm/kg
Oxygen (WB)  
Saturation, arterial 96%–100%
   Saturation, venous 60%–85%
   Partial pressure (pO2) 80–100 mm Hg
Oxygen dissociation, P50 (RBCs) 26–30 mm Hg
pH (WB) 7.38–7.44
Phenylalanine (S, P)  
   <1 month 38–137 μmol/L
   1–24 months 31–75 μmol/L
   2–18 years 26–91 μmol/L
   >18 years 35–85 μmol/L
Phosphatase, acid (PAP) 0–5.5 U/L
Phosphatase, alkaline (ALP) (S)10  
   1–3 years 145–320 U/L
   4–6 years 150–380 U/L
   7–9 years 175–420 U/L
 
   10–11 years
   12–13 years
   14–15 years
   16–19 years
   Adult
Males Females
135–530 U/L 130–560 U/L
200–495 U/L 105–420 U/L
130–525 U/L    70–230 U/L
   48–261 U/L 40–136 U/L
  30–120 U/L
Phosphorus, inorganic (S)  
   1–5 days 4.8–8.2 mg/dL
   1–3 years 3.8–6.5 mg/dL
   4–11 years 3.7–5.6 mg/dL
   12–15 years 2.9–5.4 mg/dL
   16–19 years 2.7–4.7 mg/dL
   Adult 3.0–4.5 mg/dL
Phospholipids (S) 150–264 mg/dL
Potassium (S) 3.5–5.0 mEq/L
Prealbumin (transthyretin)  
   <6 weeks   4–36 mg/dL
   ≥16 years 13–27 mg/dL
   Adult 19.5–35.8 mg/dL
Prostate-specific antigen (PSA) (S) Males
Values higher in black men than in white men. Increases with age.		  
   Normal <4.0 ng/mL
   Borderline 4–10 ng/mL
   40–49 years 1.5 ng/mL
   50–59 years 2.5 ng/mL
   60–69 years 4.5 ng/mL
   70–79 years 7.5 ng/mL
PSA, free, males (S) >25% associated with BPH
PSA (S) females <0.5 ng/dL
Proteins (S)
   Term
   7–19 years
   Adult
Total (g/dL) Albumin (g/dL)
4.6–7.4 2.5–3.4
6.3–8.6 3.7–5.6
5.5–8.0 3.5–5.5
  Globulin (g/dL)
   <1 year 0.4–3.7
   1–3 years 1.6–3.5
   4–9 years 1.9–3.4
   Adult 2.0–3.5
   Electrophoresis (S)  
      Albumin 3.5–5.5 g/dL (50%–60%)
      Globulin  
         Alpha1 0.2–0.4 g/dL (4.2%–7.2%)
         Alpha2 0.5–0.9 g/dL (6.8%–12%)
         Beta 0.6–1.1 g/dL (9.3%–15%)
         Gamma 0.7–1.7 g/dL (13%–23%)
Immunoglobulins (95% confidence interval [CI]) (S) IgG (mg/dL) IgM (mg/dL) IgA (mg/dL)
   Cord blood 636–1,606 6.3–25 1.4–3.6
   1 month 251–906 20–87 1.3–53
   2 months 206–601 17–105 2.8–47
   3 months 176–581 24–89 4.6–46
   4 months 196–588 27–101 4.4–73
   5 months 172–814 33–108 8.1–84
   6 months 215–704 35–102 8.1–68
   7–9 months 217–904 34–126 11–90
   10–12 months 294–1,069 41–149 16–84
   1 years 345–1,213 43–173 14–106
   2 years 424–1,051 48–168 14–123
   3 years 441–1,135 47–200 22–159
   4–5 years 463–1,236 43–196 25–154
   6–8 years 633–1,280 48–207 33–202
   9–10 years 608–1,572 52–242 45–236
   Adult 639–1,349 56–152 70–312
Immunoglobulins G subclasses (95% CI) (S) IgG1 (mg/dL) IgG2 (mg/dL) IgG3 (mg/dL) IgG4 (mg/dL)
   0–1 year 190–620 30–140 9–62 6–63
   1–2 years 230–710 30–170 11–98 4–43
   2–3 years 280–830 40–240 6–130 3–120
   3–4 years 350–790 50–260 9–98 5–180
   4–6 years 360–810 60–310 9–160 9–160
   6–8 years 280–1,120 30–630 40–250 11–620
   8–10 years 280–1,740 80–550 22–320 10–170
   10–13 years 270–1,290 110–550 13–250 7–530
   13 years–adult 280–1,020 60–790 14–240 11–330
   IgD (S) 0–14 mg/dL
IgE (95% CI) (S)
   0 days 0.04–1.28 IU/mL
   6 weeks 0.08–6.12 IU/mL
   3 months 0.18–3.76 IU/mL
   6 months 0.44–16.3 IU/mL
   9 months 0.76–7.31 IU/mL
   1 years 0.80–15.2 IU/mL
   2 years 0.31–29.5 IU/mL
   3 years 0.19–16.9 IU/mL
   4 years 1.07–68.9 IU/mL
   7 years 1.03–161.3 IU/mL
   10 years 0.98–570.6 IU/mL
   14 years 2.06–195.2 IU/mL
   17–85 years 1.53–114.0 IU/mL
Bence Jones protein (S) 0
   Qualitative (U) 0 in 50× concentrated specimen
   Quantitative (U)  
         Kappa (κ) <2.5 mg/dL
         Lambda (λ) <5.0 mg/dL
Beta2-microglobulin (S) <0.27 mg/dL
Beta2-microglobulin (U) <120 μg/day
Sodium 135–145 mEq/L
Transaminases  
   Aspartate aminotransferase (AST; serum glutamic oxaloacetic transaminase [SGOT])11  
         1–3 years 20–60 U/L
         4–6 years 15–50 U/L
         7–9 years 15–40 U/L
         10–11 years 10–60 U/L
         >16 years 0–35 U/L
 
         12–15 years
         >16 years
Males Females
15–40 U/L 10–30 U/L
0–35 U/L
   Alanine aminotransferase (ALT; serum glutamic pyruvic transaminase [SGPT])11  
         1–3 years May be slightly higherin young children
         10 years–adult 0–35 U/L
Triglyceride (S) 25–175 mg/dL
Troponin I (S) <1.6 ng/mL
Troponin T (S) <0.1 ng/mL
Urea nitrogen (BUN) (S) 10–20 mg/dL
Uric acid (S)
Males Females
2.5–8.0 mg/dL 1.3–6.0 mg/dL
Urobilinogen (U) 1–3.5 mg/24 hr
Viscosity (correlates with fibrinogen, HDL-cholesterol) (S, P) 1.6–2.0 relative units
Vitamin A (S) 20–100 μg/dL
Vitamin B1 (thiamine) (S) 0–2 μg/dL
Vitamin B2 (riboflavin) (S) 4–24 μg/dL
Vitamin B6 (S) 5–30 ng/dL
Vitamin C (ascorbic acid) (S) 0.4–1.0 mg/dL
Vitamin D3 (1,25-dihydroxy-vitamin D) (S) 25–45 pg/mL
Vitamin D3 (25-dihydroxy-vitamin D) (S) 10–68 ng/mL
Vitamin E (S) 5–18 μg/dL
Vitamin K (S) 0.13–1.19 ng/mL
P, plasma; S, serum; U, urine; WB, whole blood.
Footnotes
9
Bock BJ, et al. The data warehouse as a foundation population-based reference intervals. Am J Clin Pathol 2003;120:662.
10
Bock BJ, et al. The data warehouse as a foundation for population-based reference intervals. Am J Clin Pathol 2003;120:662.
11
Bock BJ, et al. The data warehouse as a foundation for population-based reference intervals. Am J Clin Pathol 2003;120:662.
P.18

P.19

P.20

P.21

Blood and Urine Hormone—Reference Values
Adrenocorticotropic hormone (ACTH) (P)  
   0800 hours 25–100 pg/mL
   1800 hours <60 pg/mL
Aldosterone (S)  
   Normal sodium diet (supine) 1–16 ng/dL
   Normal sodium diet (standing) 4–31 ng/dL
   Low sodium diet (supine) 2–5× supine value
Aldosterone (U)  
Normal sodium diet 6.0–25 μg/24 hr
   Low sodium diet 17.0–44.0 μg/24 hr
   High sodium diet 0.0–6.0 μg/24 hr
Androstenedione (S)  
   Child 5–50 ng/dL
   Adult 50–250 ng/dL
Angiotensin-converting enzyme <40.0 U/L
      (ACE) (S)  
Calcitonin (P)  
   Basal Males, <19 pg/mL; females, <14 pg/mL.
   Calcium infusion (2.4 mg calcium/kg) Normal increase is <0.2 ng/mL above basal level. See Chapter 13.
   Pentagastrin infusion (0.5 μg/kg)  
Catecholamine fractionation (free) (P)
 
   Norepinephrine
   Epinephrine
   Dopamine
Supine Standing
(at least 30 min.)
100–400 pg/mL 300–900 pg/mL
≤70 pg/mL ≤110 pg/mL
<30 pg/mL (any posture)
Catecholamine fractionation (U)
   Norepinephrine
      <1 year 0–10 μg/24 hr
      1–2 years 1–17 μg/24 hr
      2–3 years 4–29 μg/24 hr
      5–7 years 8–45 μg/24 hr
      8–10 years 13–65 μg/24 hr
      >11 years 15–100 μg/24 hr
   Epinephrine
      <1 year <2.5 μg/24 hr
      2 years <3.5 μg/24 hr
      3–4 years <6.0 μg/24 hr
      5–7 years <10 μg/24 hr
      >8 years <20 μg/24 hr
Dopamine
      <1 year <85 μg/24 hr
      2 years 10–140 μg/24 hr
      3–4 years 40–260 μg/24 hr
      >5 years 60–400 μg/24 hr
Catecholamine metabolites fractionation (U)
Homovanillic acid (HVA) (random)
   <1 year <32.6 μg/mg creatinine
   2–4 year <22 μg/mg creatinine
   5–9 years <15.1 μg/mg creatinine
   10–19 years <12.8 μg/mg creatinine
   >20 years <7.6 μg/mg creatinine
   24-Hour urine <8 mg/24 hr
Metanephrines (U) <1.3 mg/24 hr
Metanephrines (S) <0.50 nmol/L
Nounatanephrines (S) <0.50 nmol/L
Vanillylmandelic acid (VMA)  
   Random 4–11.8 μg/mg creatinine
   24-Hour urine 2.6–7.7 mg/24 hr
Chorionic gonadotropins, beta-subunit (S)  
   Females, nonpregnant <5 IU/L
   Postmenopausal females <9 IU/L
   Males <2.5 IU/L
   Cerebrospinal fluid (CSF) ≤1.5 IU/L
Cortisol (for general screening) (S) 8 AM–noon: 5–25 μg/dL
  Noon–8 PM: 5–15 μg/dL
  8 PM –8 AM: 0–10 μg/dL
Cortisol, free (U) 20–70 μg/24 hr
Deoxycorticosteroids (for metyrapone test), plasma AM: 0–5 μg/dL
PM: 0–3 μg/dL
Dehydroepiandrosterone (DHEA) (S)
   <6 years
   6–8 years
   8–10 years
   10–12 years
   12–14 years
   Adult
Males Females
26–72 ng/dL 19–42 ng/dL
29–66 ng/dL 73–165 ng/dL
53–135 ng/dL 74–180 ng/dL
183–383 ng/dL 234–539 ng/dL
240–520 ng/dL 224–611 ng/dL
180–1,250 ng/dL 130–980 ng/dL
Dehydroepiandrosterone sulfate (DHEA-S) (S)
 
   1–5 years
   6–11 years
   12–17 years
   Adult
Males Females
<10 μg/mL  
10–150 μg/mL  
30–550 μg/mL  
10–619 μg/mL 12–535 μg/mL premenopausal; 30–160 μg/mL postmenopausal
Estradiol (S, P)  
   Adult males <20 pg/mL
   Premenopausal females  
      Follicular phase ≤145 pg/mL
      Midcycle peak 112–443 pg/mL
      Luteal phase ≤241 pg/mL
   Postmenopausal females <59 pg/mL
Estrone (S, P)  
   Female  
      Follicular phase of menstrual cycle 1.5–15.0 pg/mL
      Luteal phase of menstrual cycle 1.5–20 0 pg/mL
      Postmenopausal 1.5–5.5 pg/mL
   Male 1.5–6.5 pg/mL
Estrogen and progesterone receptor assays (tissue)  
   Negative <3 fmol/mg cytosol protein
   Borderline 3–9 fmol/mg cytosol protein
   Positive ≥10 fmol/mg cytosol protein
Follicle-stimulating hormone (FSH) (S/P)  
   Adult male 1–12 mIU/L
   Adult female, menstruating  
      Follicular 3.0–20.0 mIU/L
      Ovulatory 9.0–26.0 mIU/L
      Luteal 1.0–12.0 mIU/L
      Postmenopausal 18–153 mIU/L
Fructosamine (S) 1.61–2.68 mmol/L
Gastrin, serum (S) <100 pg/mL
Glucagon (P) 20–100 pg/mL
Growth hormone (S) 0.5–17 ng/mL
5-Hydroxyindolaeacetic acid (5-HIAA) (U) <6 mg/24 hr
17-Hydroyxprogesterone (U)  
   Males 5.0–250 ng/dL
      Prepubertal 0–80 ng/dL
   Females  
      Follicular phase 20–100 ng/dL
      Luteal phase 100–500 ng/dL
      Postmenopausal ≤70 ng/dL
      Prepubertal 0–90 ng/dL
Insulin (S, P) 2–20 μU/mL
17-Ketogenic steroids (total adrenal corticosteroids) (U)  
   Adults, males 5–23 mg/24 hr
      Females 3–15 mg/24 hr
   Children, <1 year <1 mg/24 hr
      1–10 years 2.3–3.8 mg/24 hr
17-Ketosteroids (U)  
   Adults, males 8–20 mg/24 hr
      Females 6–15 mg/24 hr
   Children, <1 year <1 mg/24 hr
      1–4 years <2 mg/24 hr
      5–8 years <3 mg/24 hr
      9–12 years 3–10 mg/24 hr
      13–16 years 5–12 mg/24 hr
17-Ketosteroids, fractionation (U) See Table 1-9
Luteinizing hormone (LH) (S)  
Prepuberty <5.0 mIU/L
   Adult males 2.0–12 mIU/L
   Adult females, follicular 2.0–15 mIU/L
   Adult females, midcycle 22.0–105.0 mIU/L
   Adult females, luteal 0.6–19.0 mIU/L
   Postmenopausal females 16.0–64.0 mIU/L
Parathyroid hormone (PTH) (S) 10–60 pg/mL
Pregnanetriol (U)
   0–5 years
   6–9 years
   10–15 years
   >16 years
Pregnenolone (S)
Males Females
<0.1 mg/24 hr <0.1 mg/24 hr
<0.3 mg/24 hr <0.3 mg/24 hr
0.2–0.6 mg/24 hr 0.1–0.6 mg/24 hr
0.2–2.0 mg/24 hr 0.0–1.4 mg/24 hr
10–200 ng/dL 10–230 ng/dL
Progesterone (S)  
Males ≤1.4 ng/mL
   Females  
      Follicular phase <0.2 ng/mL
      Midluteal phase 3.0–20.0 ng/mL
Prolactin (S)  
   Males 0–15 ng/mL
   Females 0–20 ng/mL
   Pregnancy 9–200 ng/dL
Renin activity (peripheral vein) (PRA) (sodium-replete, upright) (P) 0.00–364 ng/mL/hour
Sex hormone binding globulin (SHBG) (S)  
   Adult males 13–71 nmol/L
   Adult nonpregnant females 18–114 nmol/L
Somatomedin-C (insulinlike growth factor; IGF-I) (S, P)  
   Age
   2 mo–5 years
   6–8 years
   9–11 years
   12–15 years
Males Females
17–248 ng/mL 17–248 ng/mL
88–474 ng/mL 88–474 ng/mL
110–565 ng/mL 117–771 ng/mL
202–597 ng/mL 261–1,096 ng/mL
  Adult
   16–24 years 182–780 ng/mL
   25–39 years 114–492 ng/mL
   40–54 years 90–360 ng/mL
   >55 years 71–290 ng/mL
Testosterone (S)
   Males
   Females
Total Free
270–1,070 ng/dL 12–40 ng/dL
6–86 ng/dL 0.2–3.1 ng/dL
Thyroxine, total (T4) (S) 4.5–10.9 μg/dL
Triiodothyronine, total (T3) (S) 60–181 ng/dL
Triiodothyronine, free (fT3) (S) 1.4–4.4 pg/dL
Reverse T3 (rT3) (S) 0.09–0.35 ng/mL
Thyroglobulin (S) 0–60 ng/mL
Thyroid-binding globulin (S) 16–24 μg/mL
Thyroid microsomal (S) <1:100
Thyroglobulin antibodies (S) <2.0 IU/mL
Thyroid peroxidase antibodies (S) <2.0 IU/mL
Thyrotropin 0.4–6.0 IU/mL
Vasoactive intestinal polypeptide (VIP) (P) <75 μg/mL
P, plasma; S, serum; U, urine.
Table 1-8. Comparison of Umbilical Artery and Vein Analytes*
Analyte Umbilical Artery Umbilical Vein
pH 7.33 ± 0.07 7.38 ± 0.06
CO2 pressure (mm Hg) 45 ± 10 38 ± 8
Bicarbonate (mEq/L) 23 ± 5 23 ± 5
O2content    
O2 pressure (mm Hg) 35 ± 15 41 ± 20
Hb (g/dL) 13 13
*Henderson Z, Ecker JL. Fetal scalp blood sampling—limited role in contemporary obstetric practice: part 1. Lab Med. 2003;34:548.
Table 1-9. 17-Ketosteroids (Fractionation), Urine (mg/24 hrs)
  Adult Females Adult Males Males 10–15 yrs Females 10–15 yrs 6–9 yrs 3–5 yrs 1–2 yrs 0–1 yr
Pregnanediol 0–4.5 0–1.9 0.1–1.2 0.1–0.7 <0.5 <0.3 <0.1 <0.1
Androsterone 0–3.1 0.9–6.1 0.2–2.0 0.5–2.5 0.1–1.0 <0.3 <0.3 <0.1
Etiocholanolone 0.1–3.5 0.9–5.2 0.1–1.6 0.7–3.1 0.3–1.0 <0.7 <0.4 <0.1
Dehydroepiandrosterone 0–1.5 0–3.1 <0.4 <0.4 <0.2 <0.1 <0.1 <0.1
Pregnanetriol 0–1.4 0.2–2.0 0.2–0.6 0.1–0.6 <0.3 <0.1 <0.1 <0.1
Δ5-Pregnanetriol 0–0.4 0–0.4 <0.3 <0.3 <0.2 <0.2 <0.1 <0.1
11-Ketoandrosterone 0–0.3 0–0.5 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1
11-Ketoetiocholanolone 0–1.0 0–1.6 <0.3 0.1–0.5 0.1–0.5 <0.4 <0.1 <0.1
11-Hydroxyandrosterone 0–1.1 0.2–1.6 0.1–1.1 0.2–1.0 0.4–1.0 <0.4 <0.3 <0.3
11-Hydroxyetiocholanolone 0.1–0.8 0.1–0.9 <0.3 0.1–0.5 0.1–0.5 <0.4 <0.1 <0.1
11-Ketopregnanetriol 0–0.5 0–0.5 <0.3 <0.2 <0.2 <0.2 <0.2 <0.2
Source: Leavelle DE, ed. Mayo Medical Laboratories Handbook. Rochester, MN: Mayo Medical Laboratories, 1995.
Table 1-10. Thyroid Function Tests by Age (Serum Concentrations)
Age Thyroid-stimulating Hormone (TSH) Reference Range (mU/L) Thyroxine, Free (fT4) Reference Range (ng/dL; pmol/L)
Midgestation fetus 0.7–11 0.15–0.34 (2–4)
Term infant 1.3–19 0.8–1.9 (10–22)
3 days 1.1–17 1.8–4.1 (22–49)
10 weeks 0.6–10 0.8–1.7 (9–21)
14 months 0.4–7.0 0.6–1.4 (8–17)
5 years 0.4–6.0 0.8–1.7 (9–20)
14 years 0.3–5.0 0.6–1.4 (8–17)
Adult 0.3–4.0 0.8–1.8 (9–22)
Pregnancy
   First trimester 0.3–4.5 0.7–2.0 (9–26)
   Second trimester 0.5–4.6 0.5–1.6 (6.5–21)
      Third trimester 0.8–5.2 0.5–1.6 (6.5–21)
*National health and nutrition examination survey. J Clin Endocrinol Metab. 2002;87:489.
P.22

Blood Antibody—Reference Values
Acetylcholine (Ach) (S)  
   Receptor-binding antibodies ≤0.02 nmol/L
   Receptor-blocking antibodies <25% blockade of ACh receptors
   Receptor-modulating antibodies <20% loss of ACh receptors
Antiadrenal antibody (S) Negative at 1:10 dilution
Antiglomerular basement membrane antibody (S)  
   Qualitative Negative
   Quantitative <5 U/mL
Antinuclear antibodies (ANA) (S) Negative at 1:40 dilution
Antimitochondrial antibodies (S) Negative
Antibodies to Scl 70 antigen (S) Negative
Antibodies to Jo 1 antigen (S) Negative
Anti-La antibody (S) Negative
Anti-ds-DNA (double-stranded) (native) antibodies (S) Negative at 1:10 dilution
Antiextractable nuclear antigens (anti-RNP, anti-Sm, anti-SSB, anti-SSA) (S) Negative
Antineutrophil cytoplasmic autoantibody, cytoplasmic (c-ANCA) (S)  
   Qualitative Negative
   Quantitative <2.8 U/mL
Antineutrophil cytoplasmic autoantibody, perinuclear (p-ANCA) (S)  
Qualitative Negative
   Quantitative <1.4 U/mL
Antigranulocyte antibodies (S) Negative
HLA-B27 present in: (S)
Whites: Blacks: Asians:
6%–8% 3%–4% 1%
Intrinsic factor blocking antibody (S) Negative
Parietal cell antibodies (S) Negative at 1:20 dilution
Antiplatelet antibodies (S) Negative
Rheumatoid factor (S, JF) <30 IU/mL
Anti–smooth muscle antibodies (S) Negative at 1:20 dilution
Anti–striated muscle antibodies (S) Negative at <1:60
Antithyroglobulin antibodies (S) Negative
Antithyroid antibodies (S) <0.3 IU/mL
S, serum.
P.23

P.24

P.25

Blood Levels for Metabolic Diseases—Reference Values
Acid mucopolysaccharides (U)  
   <14 years   Age dependent
   >14 years   <3.4 mg/mmol creatinine
Alpha1 antitrypsin (S)   85–213 mg/dL
Alpha-fucosidase (F) Compare with controls
  (L) 0.49–1.76 U/g cellular protein
Alpha-galactosidase (Fabry disease) (S) 0.016–0.2 U/L
  (F) 0.24–1.10 U/g cellular protein
  (L) 0.60–3.63 U/1010 cells
Alpha-glucosidase (F) 0.13–1.84 U/g protein
Alpha-L-iduronidase (Hurler, Scheie syndrome) (F) 0.44–1.04 U/g cellular protein
  (L) 0.17–0.54 U/1010 cells
Alpha-mannosidase (mannosidosis) (F) 0.71–5.92 U/g cellular protein
  (L) 1.50–3.33 U/1010 cells
Alpha-N-acetylglucosaminidase (S) 0.09–0.58 U/L
      (Sanfilippo type B) (F) 0.076–0.291 U/g cellular protein
Arylsulfatase A (mucolipidosis, Type II and III) (F) 2.28–15.74 U/g cellular protein
  (L) ≥2.5 U/1010 cells
  (U) >1 U/L
Arylsulfatase B (F) 1.6–14.9 U/g cellular protein
Beta-galactosidase (Gm1, gangliosidosis, Morquio syndrome) (F) 4.7–19.1 U/g cellular protein
  (L) 1.01–6.52 U/1010 cells
Beta-glucosidase (Gaucher disease) (F) 3.80–8.70 U/g cellular protein
  (L) 0.08–0.35 U/1010 cells
Beta-glucuronidase (MPS VII) (F) 0.34–1.24 U/g cellular protein
Carbohydrate (U) Negative
Cystine (U)  
   <1 month 64–451 μmol/g creatine
   1–5 months 66–375 μmol/g creatine
   6–11 months 70–316 μmol/g creatine
   1–2 years 53–244 μmol/g creatine
   3–15 years 11–53 μmol/g creatine
   ≥16 years 28–115 μmol/g creatine
   Linoleate ≥25% of fatty acids in serum lipids
   Arachidonate ≥6% of fatty acids in serum lipids
   Palmitate 18%–26% of fatty acids in serum lipids
   Phytanate ≤0.3% of fatty acids in serum lipids (>0.5% suggests Refsum disease 0.3%–0.5% borderline)
Free fatty acids (S) 239–843 μEq/L
Galactose (U) Not detectable
Galactose 1-phosphate (RBC)  
   Nongalactosemic 5–49 μg/g Hb
   Galactosemic (galactose-restricted diet) 80–125 μg/g Hb
   Galactosemic (unrestricted diet) >125 μg/g Hb
Galactose-1-phosphate uridylyl-transferase (galactosemia) (WB) 18.5–28.5 U/g Hb
   <2 years old 20–80 mU/g Hb
   ≥2 years old 12–40 mU/g Hb
Galactosylceramide-beta-galactosidase (F) 10.3–89.7 mU/g cellular protein
   (Krabbe’s disease, globoid cell leukodystrophy) (L) >21.5 mU/g cellular protein
Glucose-6-phosphate dehydrogenase (G-6-PD) (WB) 4.6–13.5 U/g Hb
Glucose phosphate isomerase (B) 49–81 U/g Hb
Hexosaminidase (≥5 years old) (Tay-Sachs, GM2 gangliosidosis)  
   Total (S) 10.4–23.8 U/L
   Hexosaminidase A
      Noncarrier >55% of total
      Indeterminate 51%–54% of total
      Carrier ≤55% of total
   Total (L) 16.4–36.2 U/g cellular protein
   Hexosaminidase A 63%–75% of total
   Total (F) 92–184.5 U/g cellular protein
   Hexosaminidase A 41%–65% of total
Homogentisic acid (U) Negative
Hydroxyproline, free (U) <1.3 mg/24 hr
Hydroxyproline, total (U)  
   <5 years old 100–400 μg/mg creatinine
   5–12 years 100–150 μg/mg creatinine
   Females ≥19 years 0.4–2.9 mg/2 hr specimen
   Males ≥19 years 0.4–5.0 mg/2 hr specimen
35S Mucopolysaccharide (MPS I, II, III, VI, VII) (F) Normal or abnormal turnover
   ≤1 week of age 0.69–2.0 mg/dL (42–124 μmol/L)
   <16 years old 0.43–1.4 mg/dL (26–86 μmol/L)
   >16 years old 0.68–1.1 mg/dL (41–68 μmol/L)
Phytanate (phytanic acid) (S) <0.3% normal
  0.3%–0.5% borderline
  >0.5% suggests Refsum disease
Porphyrins, Qualitative (U) None
Porphyrins, Qualitative (St) None
Porphyrins, total (RBC) 16–60 μg/dL packed cells
   Uro (octacarboxylic) ≤2 μg/dL
   Hepatocarboxylic ≤1 μg/dL
   Hexacarboxylic ≤1 μg/dL
   Pentacarboxylic ≤1 μg/dL
   Copro (tetracarboxylic) ≤2 μg/dL
Porphyrins, Total (P) ≤1 μg/dL
   Fractionation ≤1 μg/dL for any fraction
Porphyrins (St)  
   Coproporphyrin ≤200 μg/24 hr
   Protoporphyrin ≤1,500 μg/24 hr
   Uroporphyrin ≤1,000 μg/24 hr
Porphyrins, fractionation (U)  
   Uroporphyrins <45 μg/24 hr
   Hepatocarboxylic <13 μg/24 hr
   Hexacarboxyl porphyrin <6 μg/24 hr
   Pentacarboxylporphyrin <5 μg/24 hr
   Coproporphyrin <110 μg/24 hr
   Porphobilinogen <2.0 mg/24 hr
Protoporphyrins, zinc (WB)  
   <15 years <35 μg/dL
   >15 years <50 μg/dL
Sphingomyelinase (Niemann-Pick disease) (F) 1.53–7.18 U/g cellular protein
Tyrosine (P)  
   <1 month 55–147 μmol/L
   1–24 months 22–108 μmol/L
   2–18 years 24–115 μmol/L
   >18 years 34–112 μmol/L
Uroporphyrinogen-1-synthase (WB) 9.2–19.1 nmol/sec/L RBC
F, skin fibroblasts; JF, joint fluid; L, leukocytes; P, plasma; RBC, erythrocytes; S, serum; St, stool; U, urine; WB, whole blood.
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