An analysis for blood manganese used to assess environmental exposure

In this graphite-furnace atomic-absorption spectrometric method for measuring manganese in whole blood, we use a pyrolytic platform to minimize interference by sample matrix. For optimal sample ashing we denature the sample within the furnace with nitric acid and use oxygen as the purge gas at low temperatures. The mean manganese concentration found in blood from 15 unexposed city dwellers was 215 (2 SD 135) nmol/L. By comparison, the range of manganese concentrations in blood sampled from a group of Australian aborigines living near a surface manganese ore deposit on Groote Eylandt, Northern Territory, was much higher (median 405 nmol/L, range 175 to 990 nmol/L).     

Avidin-biotin enzyme immunoassay of osteocalcin in serum or plasma.

We describe a competitive enzyme immunoassay, the ExtrAvidin-biotin system, for determining osteocalcin in human serum or plasma. Antibodies were raised against bovine osteocalcin. Binding of the antibodies to osteocalcin was calcium-dependent. Limit of detection is 0.07 nmol/L (0.4 microgram/L). The standard curve for method is linear between 0.3 and 17.6 nmol/L (1.9 and 100 micrograms/L). Interassay CV over the range 0.9 to 14.8 nmol/L (5.3 to 84 micrograms/L) is 7.5% to 11.7%. Analytical recovery is 105% +/- 5% (mean +/- SD). The measurement, which is adapted to microtiter plates, requires only 20 microL of serum and 5 h. The coefficient of correlation between the concentrations measured by this method and by a commercially available radioimmunoassay kit (CIS Biointernational) is 0.91. Osteocalcin can be measured in serum or heparinized plasma. Hemolysis (174 mumol/L hemoglobin) reduces osteocalcin concentration by 54%. High concentrations of triglycerides (7 mmol/L) give an overestimation of 63%. Serum concentrations of osteocalcin measured in 130 healthy subjects (ages 15-64 years) and 86 children (ages 4-14 years) were 1.4 +/- 0.8 and 4.0 +/- 1.5 nmol/L (8.1 +/- 4.6 and 22.5 +/- 8.6 micrograms/L), respectively (mean +/- SD).     

Determination of manganese in whole blood and serum.

We describe methods for determination of manganese in whole blood and serum with Zeeman-effect flameless atomic absorption spectroscopy. These analyses are performed on a twofold or fourfold dilution of the specimen in Triton X-100, 1 g/L. No predigestion or extraction procedures are required. The method of standard additions was used for quantitation. Within-run coefficients of variation for whole-blood manganese were 7.0 and 5.5% for 2.29 and 5.67 micrograms/L, respectively. For determination of serum manganese, coefficients of variation were 10.3 and 5.3% for 0.97 and 3.01 micrograms/L, respectively. Manganese detection limits for the assays were 3.0 pg. Whole-blood manganese concentrations, determined for 60 subjects, yielded a mean (+/- SD) of 9.03 (+/- 2.25) micrograms/L. Mean serum manganese concentration, determined for 20 subjects, was 1.82 (+/- 0.64) microgram/L. No correlation was found between blood manganese concentrations and age, sex, or smoking status.     

Assay of carboxypeptidase N activity in serum by liquid-chromatographic determination of hippuric acid

We describe conditions for determining carboxypeptidase N (EC 3.4.17.3) activity by liquid chromatography. Serum (10 microL) is mixed with the artificial substrates hippuryl-L-arginine (30 mmol/L) and hippuryl-L-lysine (100 mmol/L) in 50 mmol/L 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES) buffer solution at pH 8.2 and 7.8, respectively. The hippuric acid product is separated from the substrate in less than 2 min by reversed-phase "high-performance" liquid chromatography and measured spectrophotometrically. o-Methyl hippuric acid is used as internal standard. By this method, optimized for activity and sensitivity of detection, carboxypeptidase N activities are 60-fold greater than those by another procedure (J Chromatogr 266:173-177, 1983). The mean value for 80 normal control subjects was 74.8 (SD 10.3) nmol of hippuric acid released per milliliter of serum per minute for hippuryl-L-arginine substrate, 378 (SD 55) for hippuryl-L-lysine substrate. The sensitivity and precision of the method make it suitable both for routine clinical determinations and as a reference procedure.     

Methylmalonic acid concentration in serum not affected in hepatic disease.

Accumulation of methylmalonic acid may provide an early clue to deficiency of cobalamin (vitamin B12) in tissue. Metabolic abnormalities involving precursors of methylmalonic acid are frequently observed in patients with hepatic diseases. To establish whether methylmalonic acid accumulates and thereby gives false-positive test results for cobalamin deficiency, we measured the concentration of methylmalonic acid in serum of patients with various hepatic diseases. Many of the patients had increased concentrations of cobalamin in serum. In serum from 70 patients, the mean concentration of methylmalonic acid (252, SE 25 nmol/L) did not differ significantly from that found in healthy subjects (211, SE 12 nmol/L). We conclude that the assay of methylmalonic acid in serum may be useful for evaluating cobalamin status in hepatic disease with functional cobalamin deficiency despite an artificially increased normal or high concentration of cobalamin in serum.     

Underestimation of monoclonal proteins by serum protein electrophoresis on cellulose acetate

Our study of 95 serum samples from 37 patients with monoclonal gammopathy revealed distorted irregular monoclonal (M) protein bands after serum protein electrophoresis (SPE) on cellulose acetate membrane. In 71 (75%) of the 95 sera, the M-protein was underestimated and the albumin concentration overestimated. Dilution of the serum sample before SPE eliminated the abnormality of the M-protein bands. By SPE, the mean albumin concentration in these 71 undiluted sera was 45.8 (SD 7.4) g/L vs 37.9 (SD 5.8) g/L for the diluted sera; moreover, this was true of individual samples: measured albumin concentration in each diluted serum sample was always less than in the undiluted serum. As measured by the bromcresol green dye-binding method, the albumin concentration was 32.8 (SD 5.9) g/L. Similarly, the M-protein concentration in SPE was 49.5 (SD 12.3) g/L for the undiluted sera vs 61.8 (SD 15.1) g/L for the diluted sera, and the M-protein concentration in each diluted serum sample always exceeded that in the undiluted serum. Underestimation of M-protein limits the usefulness of M-protein measurement in evaluating the patient's response to therapy and for early detection of disease progression. SPE strips should be carefully inspected visually, and sera with M-protein band abnormalities should be diluted and re-assayed if SPE is to quantify concentrations of M-protein and albumin accurately.     

Quantitative nephelometric assay for determining myoglobin evaluated

A recently introduced automated nephelometric immunoassay involving shell/core particles for determination of myoglobin (Behringwerke) was evaluated with the BNA Nephelometer. Method precision was good: the intra-assay CV varied between 1.5% and 6.1%; with daily calibration, the interassay CV ranged between 1.5% and 7.5%. For usual sample dilutions, the assay response varied linearly with myoglobin concentrations up to 23.1 nmol/L. After automatic dilution by the instrument, concentrations up to 2310 nmol/L could be measured without high-dose "hook" effect. Further manual dilution allowed measurement of myoglobin concentrations up to 26,000 nmol/L. Calibration was stable for at least seven days. We detected no significant interferences from hemoglobin, haptoglobin, bilirubin, iodine-containing contrast media, and rheumatoid factors. Treating lipemic samples with Lipoclean (Behringwerke) decreased test results. Simultaneously drawn serum and plasma samples from the same subject showed no consistent differences in myoglobin concentrations. The mean reference myoglobin concentration was 1.380 (SD 0.82) nmol/L for men and 0.878 (SD 0.45) nmol/L for women. In patients with renal insufficiency, serum creatinine values were moderately related to serum myoglobin values (r = 0.465). Although a commercial radioimmunoassay (Byk-Sangtec) and the nephelometric assay intercorrelated well (r = 0.929), values obtained by nephelometry were significantly lower (P less than 0.05). By both assays, results for heart and skeletal muscle tissue extracts showed no correlation, a finding that suggests the existence of multiple forms of myoglobin in human tissues. We conclude that immunonephelometry is a rapid, practical, and reliable method for measuring myoglobin in serum.     

Serum cortisol/cortisone ratio after Synacthen stimulation

OBJECTIVES: 11beta-Hydroxysteroid dehydrogenase (11beta-HSD) enzymes interconvert active cortisol and inactive cortisone. There is growing evidence that local tissue concentrations of cortisol are generally modulated by site specific different 11beta-HSD actions. While 11beta-HSD type 2 unidirectionally inactivates cortisol, type 1 isoform acts bidirectionally. 11beta-HSD type 1 is mainly localized in the liver and may thus restore circulating biologically inactive cortisone to active cortisol thereby modulating systemic glucocorticoid action; such a mechanism might be of importance in stressful situations. To study this hypothesis we investigated the influence of exogenous ACTH on serum cortisol/cortisone ratio. DESIGN AND METHODS: Paired serum samples that were submitted for routine analysis of cortisol before and 1 h after stimulation with 250 microg ACTH (1-24) (Synacthen) were collected prospectively if the routine tests indicated normal adrenal function; 40 patients were included in the study, 29 patients were female, 11 male, median age was 31 yr (range 14-70). Serum cortisol and cortisone were determined using LC-ESI/MS/MS with an online sample extraction system and tri-deuterated cortisol as the internal standard. RESULTS: While mean serum cortisol increased by 109% (mean basal concentration 373 nmol/L (SD 151 nmol/L), stimulated 781 nmol/L (SD 194 nmol/L)), mean serum cortisone significantly decreased after ACTH administration by 31% (p < 0.001, paired t-test for differences). Mean serum cortisone was 70 nmol/L (SD 16 nmol/L) before and 48 nmol (SD 16 nmol/L) after ACTH administration; decrease in serum cortisone was observed in 34 (85%) of the patients. The ratio of serum cortisol/cortisone increased in all subjects (mean 5.4 (SD 1.9) before ACTH, and 16.2 (SD 6.2) after ACTH; p < 0.001). CONCLUSIONS: The data of our observational study suggest a modulation of peripheral metabolism of cortisol by ACTH with a stimulation of systemic 11beta-HSD type 1 activity, leading to restoration of inactive cortisone to biologically active cortisol.     

Stability of free apolipoprotein A-1 concentration in serum, and its measurement in normal and hyperlipidemic subjects

Free apolipoprotein A-1 (free A-1) is a low-molecular-mass complex of protein and lipid containing apolipoprotein A-1 (apo A-1). Using crossed immunoelectrophoresis, we separated free A-1 from the apo A-1 in high-density lipoproteins (HDL) and quantified free A-1 by comparison with a reference serum (containing 1.45 g of apo A-1 per liter) diluted in 9 mol/L urea solution. This latter treatment yields apo A-1 containing protein-lipid complexes of the same size and electrophoretic mobility as free A-1. Within-day precision (CV), determined by replicate analysis of two samples with mean free A-1 concentrations of 48 and 138 mg/L, was 9.1 and 7.2%, respectively. We also showed that the concentration of free A-1 is not stable in serum or plasma either at 4 degrees C or when frozen. The mean concentration of free A-1 in 28 fasted, healthy subjects was 75.3 (SD 13.6) mg/L. The postprandial increase was not statistically significant. The percentage of total apo A-1 in the free form in serum ranged from 3.5% to 8.1%, less than the 10% to 30% reported by others who used radial immunodiffusion to measure free A-1. Because radial immunodiffusion does not separate free A-1 from HDL, we believe that that technique overestimates free A-1. We also used crossed immunoelectrophoresis to measure free A-1 in 76 hyperlipidemic patients. Those with Fredrickson types III and V had significantly increased concentrations of free A-1 (P less than .0001). Correlations between free A-1 and cholesterol and triglycerides in serum were significant (P less than .005 and P less than .001, respectively). Possible roles for free A-1 in lipid metabolism are discussed.     

Enzyme-linked immunosorbent assay of retinol-binding protein in serum and urine

This highly sensitive method for determining retinol-binding protein in human serum and urine is based on a double-antibody "sandwich"-type enzyme-linked immunosorbent assay. The assayable concentration range is 0.8-48 micrograms/L, the detection limit 0.2 micrograms/L. Within-assay coefficients of variation for 10 determinations at two different concentrations were 5.5 and 5.8%. The corresponding between-assay CVs were 7.9 and 9.2%. We saw no interference from any components of urine or serum. The mean urinary excretion by 30 healthy subjects, as determined by this method, was 101 micrograms/g of creatinine (SD 38.8). The concentration in serum averaged 43 mg/L (SD 12.1).     

Immunoreactive phospholipase A2 in serum in acute pancreatitis and pancreatic cancer

Immunoreactive phospholipase A2 (EC 3.1.1.4) was measured by a new sensitive time-resolved fluoroimmunoassay in the serum of 58 healthy subjects and 103 patients with acute pancreatitis. Patients with acute pancreatitis were grouped according to the etiology and clinical severity of the disease. The mean phospholipase A2 concentration in the reference (healthy) group was 5.5 (SD 1.9) micrograms/L. In acute pancreatitis the mean phospholipase A2 concentration was increased on the first day after hospital admission in all groups, and returned to normal somewhat more slowly than did serum amylase, especially in the patients with severe alcoholic pancreatitis. In this latter group the mean concentration of serum phospholipase A2 on the first day was 42.6 (SD 29.5) micrograms/L. In patients with pancreatic cancer, serum phospholipase A2 was 29.2 (SD 21.3) micrograms/L. The phospholipase A2 and amylase values were closely associated in all groups. The clinical sensitivities were 90.9% for severe alcoholic pancreatitis and 87.5% for pancreatic cancer. Immunochemical determination of phospholipase A2 in serum provides fast and specific detection of injury to pancreatic acinar cells. In addition to the early diagnosis of acute pancreatitis, follow-up determinations of phospholipase A2 seem to be useful in differentiating between mild and severe forms of pancreatitis.     

Immunonephelometric determination of retinol-binding protein in serum and urine

An immunonephelometric method developed for measurement of retinol-binding protein (RBP) in serum and urine can detect it in concentrations of about 30 micrograms/L, which is in the lower limit of its normal concentration in urine (range 0-0.56 mg/L; mean +/- SD 0.19 +/- 0.15; n = 44). Urinary RBP was increased (range 0.93-29.5 mg/L) in all of 25 urine specimens from 13 subjects being treated with aminoglycoside (tobramycin). Urinary excretion of RBP was correlated (r = 0.83) with the excretion of beta 2-microglobulin. The within-assay and day-to-day precision (CV) was determined over the detection range of 0.03-8 mg/L. Within these limits the corresponding CVs varied from 4 to 27% and from 8 to 30%, respectively. The method had fairly good precision within the optimal measuring range of approximately 0.4 to 4.5 mg/L for both urine and 20-fold diluted serum samples. For various RBP concentrations our analytical recovery was 89-114% of added RBP. Results by this method correlated well (r = 0.96, n = 24) with those by a radial immunodiffusion method.     

Oxidative stress and high-density lipoprotein function in Type I diabetes and end-stage renal disease

In a cross-sectional study, oxidative stress in high vascular disease risk groups, ESRD (end-stage renal disease) and Type I diabetes, was assessed by measuring plasma protein carbonyls and comparing antioxidant capacity of HDL (high-density lipoprotein) as pertaining to PON1 (paraoxonase 1) activity and in vitro removal of LPO (lipid peroxides). ESRD subjects on haemodialysis (n=22), Type I diabetes subjects (n=20) without vascular complications and healthy subjects (n=23) were compared. Plasma protein carbonyls were higher in ESRD patients [0.16 (0.050) nmol/mg of protein; P=0.001; value is mean (SD)] relative to subjects with Type I diabetes [0.099 (0.014) nmol/mg of protein] and healthy subjects [0.093 (0.014) nmol/mg of protein]. Plasma PON1 activity, with and without correction for HDL-cholesterol, was lower in diabetes but did not differ in ESRD compared with healthy subjects. Plasma PON1 activity, without correction for HDL, did not differ between the three groups. In ESRD, plasma PON1 activity and plasma protein carbonyl concentrations were inversely related (r=-0.50, P<0.05). In an in vitro assay, LPO removal by HDL in ESRD subjects was greater than HDL from healthy subjects (P<0.01), whereas HDL from patients with Type I diabetes was less effective (P<0.01). Efficacy of LPO removal was unrelated to plasma PON1 activity, in vitro glycation or mild oxidation, but was impaired by marked oxidation and glycoxidation. Protein carbonyl levels are increased in ESRD but not in complication-free Type I diabetes. HDL antioxidant function is increased in ESRD, perhaps a compensatory response to increased oxidative stress, but is lower in Type I diabetes. HDL dysfunction is related to glycoxidation rather than glycation or PON1 activity.     

Radioimmunoassay of testosterone not bound to sex-steroid-binding protein in plasma

To measure the concentration of testosterone (T) that is not bound to sex-steroid-binding protein (SBP) in plasma, we quantified by radioimmunoassay the T in the supernates of plasma samples after precipitation with 50%-saturated ammonium sulfate. The concentrations of non-SBP-bound T. directly measured with this assay, correlated significantly (P less than 0.001) with those deduced from measurement of the percentage of non-SBP-bound T determined with [3H]T as tracer or from mathematical models according to the law of mass action. It also correlated significantly with the ratio of T to SBP and with the concentration of nonbound T. As determined with this assay, the mean concentration of non-SBP-bound T in normal men was higher in young (4.67, SD 2.68 nmol/L; n = 30) than in older (greater than 40 years) subjects (2.48, SD 1.61 nmol/L; n = 35; P less than 0.001) and lower than normal in hyperthyroid (1.61, SD 0.91 nmol/L; P less than 0.01) or infertile men (3.28, SD 1.70 nmol/L; P less than 0.01). In women, non-SBP-bound T was higher in hirsute patients (0.24, SD 0.11 nmol/L; P less than 0.01) and was lower during pregnancy (0.09, SD 0.05 nmol/L; P less than 0.05) than in normal women during the follicular phase (0.16, SD 0.07 nmol/L). We conclude that this direct measurement of non-SBP-bound T in plasma is suitable for routine use and represents a reliable index of androgenicity in human pathology, particularly when alterations of the binding capacity of SBP modify the concentrations of total T.     

Determining zinc coproporphyrin in maternal plasma--a new method for diagnosing amniotic fluid embolism.

We measured the concentration of zinc coproporphyrin I (ZnCP-I), a characteristic component of meconium, in maternal plasma by fluorometry after HPLC. We obtained plasma samples from 89 women: 35 at weeks 10-40 of normal pregnancy, 41 shortly after normal delivery, 4 from patients with amniotic fluid embolism (AFE), and 9 from non-AFE patients with intra- or postpartum shock caused by genital bleeding. The plasma ZnCP-I concentration was 97 (SD 83, range 38-240) nmol/L in the AFE patients, 11 (SD 9.2) nmol/L in the non-AFE patients, 12 (SD 7.9) nmol/L during normal pregnancy, and 26 (SD 10) nmol/L shortly after normal delivery. We suggest that measuring ZnCP-I in maternal plasma by fluorometry on HPLC is a rapid, noninvasive, and sensitive method for diagnosing AFE and propose 35 nmol/L as the cutoff value for the ZnCP-I concentration in maternal plasma for the diagnosis of AFE.     

Improved determination of manganese in hair by use of a mini-autoclave and flameless atomic absorption spectrometry with Zeeman background correction: an evaluation in unexposed subjects

Motivated by the relatively wide range of values published hitherto, we offer a new, reliable method for determination of manganese in hair from unexposed human subjects. By using a mini-autoclave, we have developed a method that obviates loss of manganese during digestion and, thanks to use of a Teflon receptacle and rigorous methodology, contamination has been minimized. We used Zeeman flameless atomic absorption spectrometry, with the method of standard additions, for quantification. Within-run CVs for concentrations of Mn of 0.26 and 0.28 microgram/g of dry hair were 3.63 and 3.93%; the day-to-day CV for a Mn concentration of 0.29 microgram/g of dry hair was 5.84%. Mean (+/- SD) analytical recovery of Mn added to samples of hair was 104% (+/- 9.2%). The mean concentration of Mn found in the hair of 15 healthy unexposed subjects was 0.26 (+/- 0.05) microgram/g dry weight. This sensitive, reproducible procedure is suitable for use in analysis for traces of Mn in hair.     

Development of an enzymatic assay for sphingomyelin with rapid and automatable performances: Analysis in healthy subjects and coronary heart disease patients

BackgroundSphingomyelin (SM) is an important choline group-containing phospholipid and is considered to be an independent risk factor for coronary heart disease.MethodsWe have developed a specific enzymatic assay for SM measurement with rapid and automatable performances by using two-reagent system involving sphingomyelinase. We performed within-run and between-run precision, linearity test, detection limit, recovery test and interference to validate this assay. Then, we measured the serum SM concentration in 194 healthy subjects and 141 consecutive patients undergoing coronary angiography.ResultsThe within-run and between-run coefficients of variation for SM concentrations were 1.1–1.3% and 1.0–1.2%, respectively. Quantitative measurements to a lower limit of 30 μmol/L were shown to be possible. The recoveries of the exogenously added SM to the control samples were 98.7%–101.5%. No effect was observed after the addition of some interference materials. The mean ± SD of the serum SM concentration in the 194 healthy subjects was 553.3 ± 100.1 μmol/L. We found that the SM concentration was significantly higher among an acute coronary syndrome subjects than among the healthy subjects (P < 0.01) and that the serum SM concentrations were significantly correlated with the serum magnesium concentration.ConclusionsWe have developed a rapid and automatable enzymatic assay for SM that enables the automatic measurement of choline-containing phospholipids. This assay may be useful for various types of biochemical and clinical research.     

An enzyme-linked immunosorbent assay for lactose synthase (galactosyltransferase) in serum and its application as a tumor marker in ovarian carcinoma

This assay for lactose synthase (galactosyltransferase, EC 2.4.1.22) in serum involves two sequential incubations: serially diluted standard or sample antigen is reacted with a fixed amount of antibody; unbound antibody is then adsorbed to wells of antigen-coated microtiter plates and determined by a second antibody directed against the first antibody and coupled to phosphatase. The standard curve is linear for galactosyltransferase concentrations of 10 to 600 micrograms/L. The within-assay CV of a serum sample was 9.3% (SD 4.1%), the between-assay was 3.8% (SD 2.4%). Serum galactosyltransferase concentrations computed from three different dilutions yielded CVs of 6.5% (SD 5.7%, n = 14). We evaluated the method's accuracy by recovery analysis and by comparing enzyme activity in serum with that of purified galactosyltransferase from human milk. The normal reference interval, as estimated from data on 27 healthy blood donors, was 60-436 micrograms/L (mean 224, SD 101 micrograms/L). We applied the assay to samples of serum from ovarian carcinoma patients grouped according to tumor burden. We also determined galactosyltransferase in ascites fluid and found these values useful for diagnosis, whereas determinations in serum may serve mainly for patient monitoring.     

Computerized method for validating laboratory reference ranges for triiodothyronine and thyroxin immunoassays

We used a computer-based method to help validate the reference ranges of assays for triiodothyronine (T3) and thyroxin (T4). A retrospective search of a database of laboratory results for the previous six months identified all patients with apparent euthyroid status, as defined by methods independent of the immunoassay under review. A computer-generated reference group (CGR Group) of 2001 records had a gaussian distribution of T4 values and a reference range (mean +/- 2 SD) of 56-161 nmol/L, compared with the supplier's suggested range for euthyroid subjects (58-148 nmol/L) and an in-house range of 60-144 nmol/L for a group of 97 normal subjects. A similar CGR Group of 1902 records gave a reference range for T3 of 0.7-2.1 nmol/L (manufacturer's range 0.8-2.8; normal subjects 0.8-2.2). An attempt to devise a reference range for thyrotropin failed when we found that its concentration in the population of patients with normal values for thyroid hormones was distributed differently from that in the normal population. The method is intended to be used in addition to conventionally derived ranges based on results for healthy subjects. It allows the laboratory to conveniently verify the reference ranges for T3 and T4 assays at regular intervals by using very large samples with appropriate age, sex, and weight distribution, drawn from the population of patients' samples submitted for analysis.     

Improved assay for alcohol dehydrogenase activity in serum by centrifugal analysis

We describe an improved method for determination of alcohol dehydrogenase (EC 1.1.1.1) activity in 60 microL of human serum, based on conversion of ethanol to acetaldehyde with simultaneous reduction of NAD+ in glycine NaOH buffer (pH 9.0) at 37 degrees C in a centrifugal analyzer. The final concentration of NAD+ was 10 mmol/L and ethanol was 20 mmol/L. The dilution curve was linear with enzyme activity up to 200 U/L, and results by this method correlated well with those by a manual method (N Engl J Med 279: 241-248, 1968). Within-run precision (CV) was 0.9 to 8.2% over the range of 4.5 to 88.1 U/L, and day-to-day precision was 5.4 to 5.6%. In sera from 198 healthy individuals, mean alcohol dehydrogenase activity was 1.6 (SD 1.2, range 0-5) U/L. To evaluate the clinical utility of determining alcohol dehydrogenase, we measured the activity of alanine aminotransferase and alcohol dehydrogenase in sera from 470 patients with various diseases in our hospital, and found that results for the two enzymes did not correlate well.