A simple and sensitive colorimetric assay of zinc in serum using cationic porphyrin.

A direct colorimetric method is presented for simple and sensitive determination of serum zinc in 0.05-ml samples, using a cationic porphyrin, alpha,beta,gamma,delta-tetrakis(4-N-trimethylaminophenyl) porphine tetratoluenesulfonate salt (ttmapp, epsilon = 41.5 x 10(4) l/mol per cm at 421 nm). 7-Iodo-8-hydroxyquinoline-5-sulfonic acid (Ferron) as an accelerator for the incorporation of zinc into ttmapp was most effective. Interference of iron, copper and conjugated bilirubin in serum can be eliminated in the presence of proteins such as albumin in serum. Within-run and between-run coefficients of variation (CV) were in the ranges of 0.76-3.59 and 2.08-5.20%. A good correlation was observed between this method and atomic absorption spectrometry (AAS).     

Relationship between plasma pyridoxal-5''-phosphate concentration and the apoenzyme content of serum aminotransferases in patients with a renal allograft

We developed a rapid fluorometric assay for measurement of serum magnesium using the ligand, 8-hydroxy-quinoline-5-sulfonate and adapted the procedure to the Multistat Fluorescence Light Scattering Centrifugal Analyzer. The standard curve extends from 0.26 to 4.11 mmol/l. There was no interference from calcium or inorganic phosphorus at concentrations of 4.95 and 5.0 mmol/l, lead, iron, zinc or copper at twice the normal levels found in serum, bilirubin at concentrations of 10 mg/dl, or lipemic samples with triglyceride concentrations of 2400 mg/dl. Citrate and EDTA lowered magnesium concentrations in serum. Analytical recovery of magnesium added to four serum specimens averaged 97%. Between-run and within-run precision of the assay gave CVs which ranged from 2.9 to 7.6%. Magnesium concentrations, measured by our fluorometric procedure, were compared with those obtained by atomic absorption and colorimetric procedures. Correlation coefficients of 0.91 and 0.88 were obtained.     

An assay for separating and quantifying four bilirubin fractions in untreated human serum using isocratic high-performance liquid chromatography

BACKGROUND: The quantification of serum bilirubin fractions has been widely performed with both the diazo-method and an enzymatic method; however, the accuracy of these methods has not been evaluated because quantitative fractional high-performance liquid chromatography (HPLC) reference methods have yet to be established. METHODS: Samples were analyzed using HPLC and Shodex Asahipak GS-320HQ columns. Human serum was subjected to HPLC using direct injection, then eluted with acetonitrile: 0.3 mol/l phosphate buffer (pH 6.5) containing 1% Brij 35 and 0.08% sodium ascorbate (30:70, v/v). RESULTS: Serum bilirubin was separated into 4 fractions; retention times of 9.24, 19.92, 24.07, 35.75 min were identified as delta bilirubin, bilirubin diglucuronide, bilirubin monoglucuronide, and unconjugated bilirubin, respectively. Mean recovery was 93.0%-99.2%. Total precision of peak retention time, height and area exhibited <4.26% variation. Detection range was 3.1 to 348 mg/l. Hemoglobin (6 g/l) and immunoglobins produced a small positive interference. beta-carotene (20 mg/l), vitamin-B2 (370 microg/l) and B(12) (9.5 microg/l) did not interfere with this analysis. Results (n=30) with this method were closely correlated to those by Adachi's HPLC method as r=0.9941 to 0.9960, slope=0.88 to 1.27, intercept=-3.2 to +4.9, for each fraction. CONCLUSIONS: Since this method was a precise quantitative HPLC method for serum bilirubin fractionation, it might be used to evaluate the accuracy and the characteristics of various routine methods for bilirubin measurement.     

Substrate induction of bilirubin conjugation and biliary excretion in the rat

1. The effect of high bilirubin loads (60 mumol/kg twice daily for 2 days) on glucuronosyltransferase activity and biliary excretion of bilirubin was studied in Wistar rats. 2. The concentration of bilirubin in serum increased from 1.1 mumol/l in controls to 5.5 mumol/l after bilirubin pretreatment. 3. Bilirubin pretreatment led to a 25% increase in hepatic UDP-glucuronosyltransferase activity. Bilirubin Tm was increased by 22% and correlated positively with glucuronosyltransferase activity. 4. The output of conjugated bilirubin in bile was enhanced but no changes in the proportion of monoconjugates to disconjugates were observed. 5. Our data suggest that prolonged treatment with bilirubin can increase biliary bilirubin excretion by inducing glucuronosyltransferase activity.     

The determination of bilirubin with a new enzymatic method (Dri-STAT bilirubin) using the Hitachi 704 selective analyzer

A new enzymatic method for the determination of bilirubin in serum and plasma by means of a Hitachi 704 selective analyzer was evaluated. This endpoint method (37 degrees C) including a sample blank showed very reliable results. The range of linearity was 0.3 to 437 mumol/l bilirubin. The within-run imprecision of three different bilirubin concentrations (n = 16) was 0.37, 0.44 and 0.76% (coefficient of variation). Between-assay imprecision (n = 15) was 0.51 to 1.76% (coefficient of variation) for five different control materials. Inaccuracy, determined with 5 control sera (assigned values: 19, 23.9, 90.7, 142.0 and 295.6 mumol/l bilirubin), was 0.14 to 4.27%. Recovery rates, determined in two spiked plasma samples, were 97.8% and 99.1%, and in six bilirubin standard solutions between 92 and 99%. The comparison with the routinely used 2.5-dichlorophenyl diazonium salt method as well as with the Jendrassik & Grof [1938) Biochem. Z. 297, 81-89) method as the reference yielded correlation coefficients of r = 0.997 and r = 0.998.     

A sensitive, direct colorimetric assay of serum iron using the chromogen, nitro-PAPS

A direct colorimetric method is presented for the determination of serum iron in 0.1-ml sized samples, using a new, water-soluble, reagent, 2-(5-Nitro-2-pyridylazo)-5-(N-propyl-N-sulfopropylamino)phenol Na salt (epsilon 585 nm = 9.4 X 10(4) l/mol per cm). Interference of copper and zinc in sera can be eliminated entirely by forming copper- and zinc-thioglycollate complexes immediately upon the dissociation of the protein-bound iron, copper and zinc by thioglycollate and sodium dodecyl sulfate. The serum blank was minimized by the use of sodium dodecyl sulfate as a protein denaturant. Within-run and between-run precision (CV) were in the range of 0.7-2.9% and 1.1-3.6%, respectively, depending on the serum iron content. A good correlation (r = 0.995) was obtained between this method and the reference method proposed by the International Committee for Standardization in Hematology.     

The effect of hypoalbuminaemia, hyperbilirubinaemia and renal failure on serum fructosamine concentration in non-diabetic individuals

We have investigated the effects of hypoalbuminaemia, hyperbilirubinaemia and renal failure on serum fructosamine concentration in 39 non-diabetic patients. All patients were hypoalbuminaemic (median serum albumin 25 g/l, range 12-34 g/l). Group 1 (n = 19) were patients with hypoalbuminaemia alone, group 2 (n = 7) with hypoalbuminaemia and impaired renal function (median serum creatinine 226 mumol/l, range 154-461 mumol/l) and group 3 (n = 13) were subjects with hypoalbuminaemia and hyperbilirubinaemia (median serum bilirubin 34 mumol/l, range 19-83 mumol/l). Serum fructosamine was significantly lower in all three groups compared to age-matched normoalbuminaemic controls, but there was no significant difference in fructosamine concentrations between the groups. There was a correlation between fructosamine concentration and serum albumin. (r = 0.82, p less than 0.001) in all three groups combined. Serum fructosamine did correlate with serum bilirubin in patients with normal renal function (r = 0.0, p less than 0.001). In patients with abnormal renal function there was no correlation between serum fructosamine and either urea (r = 0.22, ns) or creatinine (r = 0.31, ns). Albumin is the major factor affecting serum fructosamine concentrations. Moderate hyperbilirubinaemia does not affect fructosamine concentration. No difference in fructosamine concentration could be demonstrated in patients with renal failure.     

Multicentre evaluation of an enzymatic method for creatinine determination using a sensitive colour reagent

A new enzymatic colorimetric method for the determination of creatinine in serum and urine (Creatinine PAP, Cat. No. 839434 and 836885, Boehringer Mannheim GmbH, Mannheim, FRG) was evaluated in 16 clinical chemistry laboratories and the manufacturer's testing laboratory. The test is based on the enzymatic degradation of creatinine and its reaction products by creatininase, creatinase and sarcosine oxidase. The H2O2 produced by the oxidation of sarcosine is determined using a modified Trinder reaction. The test can be carried out either manually or in mechanized analysers which enable the pipetting of a starter reagent to be made. The following results were obtained: Depending on the analyte concentration (range 40 to 1240 mumol/l), medians for the coefficients of variation were: 4.6-0.9% within-run and 6.4-2.8% between-day. At 546 nm the linear measuring range extended from 13 mumol/l (detection limit) to 1780 mumol/l, at 510 nm from 9 to 890 mumol/l. Recoveries in aqueous and human serum based standards as well as method comparisons with Fuller's earth methods and an enzymatic UV test indicate a high accuracy of this new enzymatic method in serum and urine. No interference was observed with haemolysed and lipaemic sera. This also applied to anticoagulants and to 36 drugs at therapeutic concentrations, with the exception of calcium dobesilate, which led to decreased values. Icteric samples containing 120-310 mumol/l bilirubin invariably led to decreased creatinine values (10-50 mumol/l lower). In a collaborative study substantially better interlaboratory agreement was observed with the new colorimetric enzymatic test than with the comparison methods (enzymatic UV test and various Jaffe procedures). In conclusion, this new enzymatic colorimetric test permits a precise and specific determination of creatinine in serum and urine. It makes a considerable contribution to improving the interlaboratory comparability of creatinine determinations and is suitable for routine use.     

Evaluation of a test kit for the rapid and simple colorimetric measurement of angiotensin I-converting enzyme in serum

We have evaluated a recently introduced colour test kit for the determination of serum angiotensin I-converting enzyme catalytic activity. p-Hydroxyhippuric acid, liberated from p-hydroxyhippuryl-L-histidyl-L-leucine by angiotensin I-converting enzyme, is converted into a quinoneimine dye with an absorption maximum at 505 nm. The procedure shows excellent linearity over the whole range of catalytic activities found in serum. Intra- and inter-assay coefficients of variation are 2-5 and 7-10% respectively. Correlation with a modified Cushman-Cheung ((1971) Biochem. Pharmacol. 20, 1637-1648) method currently used in our laboratory is good, with r = 0.985 and a regression equation of y (colour kit) = 0.423 x (Cushman-Cheung) + 0.765. Haemoglobin, lipids, bilirubin and prednisone do not interfere but uric acid in concentrations higher than 600 mumol/l does. No extraction step is required. The assay is very rapid, and more than twenty samples can be determined in an hour.     

The influence of gestational age on bilirubin conjugation in newborns

Unconjugated, mono- and diconjugated bilirubin levels were determined in serum soon after birth, and followed up for several days. Fourteen preterm neonates were studied with a gestational age below 33 weeks (n = 7) or between 34 and 37 weeks (n = 7), respectively, as well as 19 full-term newborns either untreated (n = 9) or treated by phototherapy (n = 10). Bilirubin and its derivatives were analysed by alkaline methanolysis and spectrometry after separation by thin-layer chromatography. In normal full-term neonates total and unconjugated bilirubin reached peak levels at days 2-4. Thereafter, a decline of 11% per day was detectable. Monoconjugates in serum amounted to 3.1 +/- 1.1% of total pigment and remained at that level. The relative amount of diconjugates increased from 0.55 +/- 0.25% (2-4th postnatal day) to 1.62 +/- 0.99% (9-13th day of life). The rapid decline of unconjugated bilirubin paralleled by an increase of diconjugates are an expression of the maturation process for bilirubin conjugation. The premature neonates with less than 33 weeks gestation exhibited an increase of unconjugated serum bilirubin up to the 4-5th postnatal day, the decline thereafter amounted 2% per day. The fraction of 2.3 +/- 1.1% monoconjugates was small and exhibited only a moderate increase in the follow up. In contrast diconjugates were undetectable or very low and remained at this level. These results suggest the presence of a more severe immaturity as well as a slower maturation process of bilirubin conjugation in preterm newborns.(ABSTRACT TRUNCATED AT 250 WORDS)     

Activities of copper,zinc-superoxide dismutase in erythrocytes and ceruloplasmin in serum in chronic ischemia of lower limbs

Cu,Zn-superoxide dismutase is an endogenous scavanger of superoxide radicals (O(2)(*-)) which also induce the synthesis of this enzyme. Ceruloplasmin is an antioxidant and acute-phase reactant. Changes in the synthesis of both enzymes are related to the metabolism of copper and zinc. Concentrations of copper and zinc were previously found to be increased in the serum and arterial wall of atherosclerotic subjects. The aim of this study was to investigate the Cu,Zn-superoxide dismutase activity in erythrocytes and ceruloplasmin activity in serum, and to measure serum concentrations of copper, zinc, and malonyldialdehyde in patients with moderate and critical chronic ischemia of the lower limbs. A group of 26 patients with chronic arterial occlusion of the lower limbs was divided into two groups depending on the degree of ischemia: moderate and critical. Cu,Zn-superoxide dismutase activity in erythrocytes was measured using the RANSOD kit, the serum ceruloplasmin oxidase activity was determined with o-dianisidine as a substrate. Copper and zinc concentrations in serum were determined by atomic absorption spectrometry. There was an increase in the ceruloplasmin activity and serum copper concentration in critical ischemia (194.4+/-51.94 U/l and 23.5+/-4.2 micromol/l, respectively) compared with moderate ischemia (139.1+/-34.9 U/l and 18.5+/-2.0 micromol/l, respectively). The Cu,Zn-superoxide dismutase activity in erythrocytes was higher in moderate ischemia (2,657+/-1,564 U/g hemoglobin) than in controls (1,205+/- 353 U/g hemoglobin), but not different from critical ischemia. There was a negative correlation for Cu,Zn-superoxide dismutase and ceruloplasmin (r=-0.60, P相似文献   

Proposal of automation of candidate reference method for the accurate serum cholesterol assay in clinical laboratories

BACKGROUND: In 2001, Japan Society of Clinical Chemistry (JSCC) recommended the cholesterol dehydrogenase (CD)-UV method as a comparative method for serum cholesterol measurement in Japan. Although the CD-UV method is intended to standardize routine laboratory tests, it requires complex manipulations, and has been difficult to use for the evaluation of clinical laboratories. We therefore attempted to automate this method using reagents specified by JSCC and developed a simple automated method. METHODS: We evaluated the simple automated method using 2 general instruments (JCA-BM12 and H-7170S). The linearity was confirmed for the range over 15.52 mmol/l. The coefficients of variation for 20 measurements of serum containing 2.5 and 6.1 mmol/l of cholesterol were < 1.0%, respectively. No interference by bilirubin, ditauro bilirubin, hemoglobin and chylomicrons was observed in this method. When measurement data with JCA-BM12 were compared with those using the comparative method, the correlation coefficient was 0.999 (n=23), the regression formula was y=0.992x - 0.0036 (mmol/l), and the bias was 0.8%. A similar data was obtained with H-7170S. Thus, in both comparisons, the bias was within the target (+/- 3.0%). CONCLUSIONS: This automated method provides a valid means of implementing the serum cholesterol measuring method recommended by JSCC.     

The determination of chloride in plasma and serum (mercury(II)-thiocyanate method) with the Greiner Electronic Selective Analyzer GSA II (author's transl)]

1. A mercury(II)-thiocyanate method for the determination of chloride in plasma and serum was adapted for the Greiner Electronic Selective Analyzer GSA II. A sample blank value and a partial reagent blank value were determined by omitting thiocyanate from the control system. 2. The course of the reaction was investigated. For a reaction time of 350-500 s, the response was linear between 30 and 130 mmol/l. Between 90 and 110 mmol/l, the deviation between the actual and the theoretical value is less than 1%. 3. The calibration must be checked and, if necessary, restandardized; this is probably due to variable contamination of the reagents with chloride ions. 4. Haemolysis, lipaemia and bilirubin do not interfere. Protein has no effect on the course of the reaction. 5. At concentrations around 100 mmol/l, the in series precision, expressed as the variation coefficient (%), is 0.3-0.6% for aqueous solutions, 0.4-0.8% for liquid control sera, and 0.8-1.5% for lyophilized control sera. 6. No carry over was detectable from samples containing 150 to those containing 10 mmol/l.     

Low-dose amphotericin B lipid complex for the treatment of persistent fever of unknown origin in patients with hematologic malignancies and prolonged neutropenia

We studied the safety of low-dose amphotericin B lipid complex (ABLC, at 1 mg/kg/day) in 30 persistently febrile (>38 degrees C for at least 5 days or with recurrent fever after 3 days of apyrexia) and neutropenic (<0.5 x 10(9)/l) adult patients with hematologic malignancies. The median age was 45 years (range 18-67), most (60%) had an acute leukemia and all had fever of unknown origin (FUO). The total duration of neutropenia was a median of 17 days (range 9-33), and the total number of days with fever 10 days (range 6-39). Seven patients experienced mild-to- moderate infusion-related adverse events (IRAE). The serum creatinine and urea increased from baseline to end of therapy in 76 and 63% of cases, but the maximum levels reached were <130 micromol/l and <11 mmol/l, respectively, in all cases. Liver enzymes showed modest but significant increases in most patients during therapy, while bilirubin decreased in 74% of cases. Response to treatment (defervescence within 6 days without developing a fungal or nonfungal infection) was seen in 22 cases (73%, 95% CI 58-89%), while 8 episodes were considered treatment failures: 2 due to persistent FUO, 1 withdrew due to IRAE, 2 developed nonfungal infections and 3 developed a presumed or definite invasive mycosis. We conclude that low-dose ABLC is very safe and well tolerated and seems as effective as c-AmB for this indication. Thus, randomized trials at this dose level appear justified to demonstrate any real benefit over c-AmB or other lipid formulations for the treatment of FUO in neutropenic patients.     

Gilbert's syndrome: diagnosis by typical serum bilirubin pattern

Analysis of serum unconjugated and conjugated bilirubin fractions by routine diazo procedures does not allow a definite diagnosis of Gilbert's syndrome. By the alkaline methanolysis procedure of Blanckaert followed by thin-layer chromatography we were able to discriminate Gilbert's syndrome even in the presence of normal serum bilirubin concentrations from healthy subjects, patients with chronic persistant hepatitis and patients with chronic hemolysis. The relative proportion of unconjugated bilirubin in serum was 95 +/- 2% in patients with Gilbert's syndrome (n = 28), 84 +/- 5% in healthy subjects (n = 29), 75 +/- 6% in patients with chronic persistant hepatitis (n = 7) and 85 +/- 3% in patients with chronic hemolysis (n = 9). The difference between Gilbert's syndrome and the control groups with normal or elevated serum bilirubin was highly significant (p less than 0.001). In Gilbert's syndrome, unconjugated bilirubin ranged between 90 and 99%, in healthy subjects between 72 and 90%, in patients with chronic persistant hepatitis between 68 and 85% and in patients with chronic hemolysis between 81 and 89% of total. An overlap was only seen in one patient with Gilbert's syndrome and in 2 healthy subjects at the 90% level. We conclude that in most patients with Gilbert's syndrome provocation tests are no longer necessary.     

Hepatocyte dysfunction and hepatic encephalopathy in Plasmodium falciparum malaria

BACKGROUND: According to the WHO, signs of hepatic dysfunction are unusual, and hepatic encephalopathy is never seen in malaria. However, in recent years, isolated cases have been reported from different parts of world. AIM: To identify the evidence for hepatocyte dysfunction and/or encephalopathy in jaundiced patients with falciparum malaria. DESIGN:Prospective observational study. METHODS: We studied 86 adult patients of both sexes who had malaria with jaundice (serum bilirubin > 3 mg%). The main outcome measures were: flapping tremor, deranged psychometric test, level of consciousness, serum bilirubin level, serum aspartate transaminase (AST) and alanine transaminase (ALT) levels, blood ammonia level, viral markers for hepatitis, ultrasonography of liver and gall bladder and electroencephalography (EEG). RESULTS: The range of serum bilirubin was 3-48.2 mg% (mean +/- SD 10.44 +/- 8.71 mg%). The ranges of AST and ALT levels were 40-1120 IU/l (294.47 +/- 250.67 IU/l) and 40-1245 IU/l (371.12 +/- 296.76 IU/l), respectively. Evidence of hepatic encephalopathy was seen in 15 patients. Asterexis was observed in 9 patients, impaired psychometric tests in 12 and altered mental state in 13. Arterial blood ammonia level was 120-427 meq/l (310 +/- 98.39 meq/l). EEG findings included presence of large bilateral synchronous slow waves, pseudo burst suppression and triphasic waves. Four patients died due to multiple organ dysfunction; the others made rapid recoveries. DISCUSSION: There is strong evidence of hepatocyte dysfunction and hepatic encephalopathy in some of these patients, with no obvious non-malarial explanation. Current guidelines may need to be revised.     

Evaluation of gravimetric assays of the H2O concentration in human serum and urine

The oven-drying method and the combined freeze- and oven-drying method for gravimetrical measurement of human serum and urine H2O concentration, as well as two reported formulas for the calculation of the serum H2O concentration were evaluated. Day-to-day precision in serum and urine (coefficient of variation (CV) less than 0.95%), and recovery in serum (95-99%) were excellent. Storage at 4 degrees C and at -20 degrees C was safe at least for 3 wk and 2 mth, respectively. For the oven-drying method, which was the most practical, reference values after fasting overnight were determined (n = 47; 99% confidence interval; serum, 48.8-51.6 mol/l; urine, 51.2-53.8 mol/l). Patients in different disease categories were tested (n = 38), and had normal values mostly. Low serum values were found in a patient after hemodialysis with ultrafiltration (47.0 mol/l), and in two patients with an extreme hyperproteinemia (48.8 mol/l) and hypercholesterolemia (48.1 mol/l), respectively. Formulas for calculation of the serum H2O concentration proved unreliable. When direct measurement is impossible, a serum value of 50.5 mol/l can be substituted.     

An enzymatic cycling method for the measurement of myo-inositol in biological samples

INTRODUCTION: A sensitive and simple enzymatic cycling method is described for the quantitation of myo-inositol in biological samples. METHODS: The method involves the use of a sensitive and simple enzymatic cycling method is described for the quantitation of myo-inositol in biological samples. The method involves use of thio-NAD(+), NADH and thermostable myo-inositol dehydrogenase (IDH; EC. 1.1.1.18) and measurement of the increase in absorbance at 405 nm of thio-NADH at 37 degrees C. RESULTS: The calibration curve for myo-inositol was linear (r=1.00) between 10 and 400 micromol/l. Analytical recoveries of exogenous myo-inositol added to serum and urine were 100-105% and 98-103%, respectively. Within-run and between-run coefficient of variation (CV) were 0.6-2.1% and 1.1-3.0%, respectively. This method was free from interference by hemoglobin, bilirubin, ascorbate, chyle, various sugars, sugar alcohol and myo-inositol phosphates. With the use of myo-inositol as a standard solution, the serum myo-inositol concentration (mean+/-SD) was significantly greater in patients with diabetes mellitus (DM) without nephropathy (73.0+/-13.8 micromol/l, n=7) than in healthy individuals without DM (61.0+/-12.4 micromol/l, n=20). The urinary myo-inositol concentration was also significantly greater in patients with DM without nephropathy (793.3+/-870.3 micromol/l, n=7) than in healthy individuals without DM (76.0+/-63.0 micromol/l, n=13). CONCLUSIONS: This new method is simple, sensitive and enables quantitative analysis of myo-inositol.     

Performance characteristics of the Access Inhibin A assay

BACKGROUND: Second trimester maternal screening using AFP, uE3, hCG, and inhibin A has shown a detection rate for Down's syndrome of 81% with a 5% false positive rate. Inhibin A may also have utility as a serum tumor marker in postmenopausal women with ovarian cancer and men with testicular stromal tumors. METHODS: The Beckman Coulter Access(R) Inhibin A assay was evaluated for limit of blank, dilution linearity, imprecision, interferences, reference intervals, and comparison to an inhibin A ELISA. RESULTS: The limit of blank was 0.1 ng/l. The assay was linear from 0.2 to 1347 ng/l. Total inter-assay CVs were <5% for control levels ranging from 24.6 ng/l to 811 ng/l. Interference studies showed recoveries of inhibin A within 10% of expected values at interferent concentrations of 10 g/l hemoglobin and 22 g/l triglycerides. No significant interference was observed at a bilirubin concentration of 400 mg/l. The 97.5th percentile upper reference limits were 6.8 ng/l for postmenopausal women and 3.0 ng/l for men. The Access assay compared to an ACTIVE ELISA showed a slope of 0.88, an intercept of -3.7 ng/l, S(y)(/x)=40 ng/l, and r=0.98. CONCLUSIONS: The analytical performance of the Access inhibin A assay is acceptable for routine laboratory testing.     

Analytical and clinical performance of two cardiac troponin I immunoassays.

Cardiac troponin I assays for Axsym (Abbott Diagnostics, Abbott Park, IL, USA) and Immuno 1 (Bayer Corporation, Tarrytown, NY, USA) analysers were evaluated. Heparin plasma or serum could be used for both assays. Samples were stable for 24 h at ambient temperature, 3 days at 4-8 degrees C and 3 months at -20 degrees C. After 10 months' storage at -80 degrees C, the recoveries were well above 100% by both assays. Total coefficients of variation for Axsym assay were 9.0%, 5.8% and 5.3% at concentrations of 2.6 microg/l, 9.83 microg/l and 34.3 microg/l respectively; for Immuno 1 these were 4.4 %, 1.6% and 1.8% at 2.3 microg/l, 6.27 microg/l and 44.35 microg/l respectively. It was > or =20% at concentration of < or =0.5 microg/l for Axysm assay and < or =0.15 microg/l for Immuno 1 assay. Recoveries were < or =90% at < or =0.22 microg/l on Axsym and at < or =1.47 microg/l on Immuno 1. Neither method showed significant interference with haemoglobin, bilirubin, triglycerides or rheumatoid factor. Correlation between the two methods was excellent (r = 0.997, Y (Axsym) = 4.2X (Immuno 1) +3.2). The highest concentrations detected in 50 healthy subjects were 0.3 microg/l and 0.1 microg/l by Axsym and Immuno 1 methods, respectively. Twelve out of 43 renal failure patients had troponin I 0.13-0.9 microg/l using Axsym method and 4 had levels of 0.07-0.13 microg/l using Immuno 1. In muscle trauma patients, troponin I was undetectable.