Mechanized determination of the apparent unbound unconjugated bilirubin concentration in serum.

1979 ◽  
Vol 25 (8) ◽  
pp. 1444-1447 ◽  
Author(s):  
R P Wennberg ◽  
L F Rasmussen ◽  
C E Ahlfors ◽  
T Valaes
Keyword(s):  
Total Bilirubin ◽  
Gel Filtration ◽  
Operation Time ◽  
Serum Samples ◽  
Bilirubin Concentration ◽  
Coefficients Of Variation ◽  
Control Serum ◽  
Total Bilirubin Concentration ◽  
Unbound Bilirubin

Abstract The peroxidase method for determining the apparent unbound bilirubin concentration in serum has been automated by use of a programmable, computer-directed spectrophotometer. This mechanized assay determines the total bilirubin concentration and apparent unbound bilirubin concentration in serum samples and titrates the serum with bilirubin to estimate the effect of increasing total bilirubin concentrations on the apparent unbound bilirubin concentration. The entire analysis requires 0.1 mL of serum and 4 min operation time, as compared with about 30 min for the manual method. The coefficients of variation for determination of the apparent unbound bilirubin concentration in bilirubin-enriched commercial control serum were 2.8% within-day and 5.6% between-day. Bilirubin--albumin binding in serum samples from infants with severe hyperbilirubinemia was analyzed by the manual peroxidase method, the automated peroxidase method, and Sephadex gel filtration. Good correlation was found among all three methods.

Influence of Glucuronosyl Bilirubin and (EZ)-Cyclobilirubin on Determination of Serum Unbound Bilirubin by UB-Analyser

2002 ◽  
Vol 39 (6) ◽  
pp. 583-588 ◽  
Author(s):  
Susumu Itoh ◽  
Kou Kawada ◽  
Takashi Kusaka ◽  
Saneyuki Yasuda ◽  
Hitoshi Okada ◽  
...  
Keyword(s):  
High Performance ◽  
Total Bilirubin ◽  
Enzyme Reaction ◽  
Serum Samples ◽  
Bilirubin Concentration ◽  
Group Iii ◽  
Group I ◽  
Unbound Bilirubin ◽  
High Concentrations

Background In the enzyme reaction for the determination of the unbound (free) bilirubin concentration by glucose oxidase and peroxidase, materials with low affinity for serum protein are reactive. The influence of these materials on the determination of serum unbound bilirubin was investigated. Methods Serum samples from patients with neonatal hyperbilirubinaemia were analysed by high-performance liquid chromatography for total glucuronosyl bilirubin concentration (TGC) and (E2)-cyclobilirubin concentration [(EZ)-C]. Based on these measurements, the samples were classified into three groups: group I [13 samples, TGC < 2 μmol/L and (EZ)-C < 2·5 μmol/L]; group II [four samples, TGC < 2 μmol/L and (EZ)-C ≥ 2·5 μmol/L]; and group III (five samples, TGC ≥ 2 μmol/L). The concentrations of total bilirubin and unbound bilirubin were measured in these same samples with a UB-analyser. When the absorbance at 460 nm was monitored, the decrease in absorbance was non-linear (concave curve). The degree of concavity was estimated (D15 value) as the deviation from linearity at 15 s. Results The D15 value was significantly higher in groups II and III than in group I. D15 value correlated significantly with TGC, (EZ)-C and unbound bilirubin concentration, and the unbound bilirubin concentration correlated significantly with TGC and (EZ)-C. Conclusion These results indicated that determination of serum unbound bilirubin concentration using the UB-analyser could be positively skewed by high concentrations of TGC and (EZ)-C.

Bilirubin monitoring – future prospects

2021 ◽  
Vol 56 (4) ◽  
pp. 175-180
Author(s):  
Joanna Berska ◽  
Jolanta Bugajska ◽  
Krystyna Sztefko
Keyword(s):  
Bilirubin Level ◽  
Total Bilirubin ◽  
Point Of Care ◽  
Total Bilirubin Level ◽  
Total Serum ◽  
Bilirubin Concentration ◽  
Transcutaneous Bilirubin ◽  
Total Bilirubin Concentration ◽  
Life Threatening

Monitoring of bilirubin concentration is essential during early neonatal life. According to the American Academy of Pediatrics Clinical Practice Guideline, the total serum bilirubin or transcutaneous bilirubin level should be measured in each infant in the first 24 hours of life. The concentration of bilirubin has been measured for 150 years. During that time the analytical methods for its determination have been significantly improved, the nomenclature of bilirubin has been also unified, but it is still unknown what concentration of bilirubin cause a life-threatening encephalopathy in the newborn. Under the current recommendations, clinical decisions to introduce phototherapy in the treatment of newborns’ hyperbilirubinemia are based on total bilirubin concentration, which is determined on biochemical analyzers and point of care testing systems. However, it is not always possible to predict encephalopathy based on the total bilirubin level. Probably in the future, as the availability of routine methods for the determination of unconjugated, free bilirubin becomes more available, measurement of “free” bilirubin will improve risk assessment for bilirubin neurotoxicity.

Atomic Absorption Determination of Serum Copper: Collaborative Study

1983 ◽  
Vol 66 (5) ◽  
pp. 1140-1142 ◽  
Author(s):  
David L Osheim ◽  
◽  
H Casper ◽  
W Colvin ◽  
R J Emerick ◽  
...  
Keyword(s):  
Collaborative Study ◽  
Current Method ◽  
Serum Copper ◽  
External Control ◽  
Serum Samples ◽  
Coefficients Of Variation ◽  
Absorption Determination ◽  
Control Serum ◽  
Aas Method

Abstract Preliminary to conducting a collaborative study on a method for copper in serum, methods used by a selected group of laboratories were surveyed. The responding laboratories were supplied with a Youden pair of bovine serum samples and requested to use their current method for serum copper. Results of the analyses and the methods used were evaluated; hypotheses were developed in our laboratory to explain some of the interlaboratory variation. For the AAS method chosen, each of 12 collaborating laboratories analyzed one blind duplicate and 2 Youden pair of serum samples. A commercially available external control serum with a certified level of copper and a 1000 mg copper/L standard were also submitted. The method requires the serum to be diluted 1 + 1 with distilled water and the standards to be diluted with 10% glycerin to approximate the viscosity of the diluted serum. The intralaboratory coefficients of variation (CV) ranged from 2.24 to 4.40% and the interlaboratory CV ranged from 2.56% to 6.05%. The method has been adopted official first action.

scholarly journals Single-Dose Pharmacokinetics of Amprenavir, a Human Immunodeficiency Virus Type 1 Protease Inhibitor, in Subjects with Normal or Impaired Hepatic Function

2000 ◽  
Vol 44 (4) ◽  
pp. 821-826 ◽  
Author(s):  
Laurence Veronese ◽  
Jacques Rautaureau ◽  
Brian M. Sadler ◽  
Catherine Gillotin ◽  
Jean-Pierre Petite ◽  
...  
Keyword(s):  
Liver Disease ◽  
Healthy Volunteers ◽  
Total Bilirubin ◽  
Laboratory Data ◽  
Hepatic Insufficiency ◽  
Pharmacokinetic Parameters ◽  
Control Group ◽  
Bilirubin Concentration ◽  
Total Bilirubin Concentration ◽  
Severe Cirrhosis

ABSTRACT Amprenavir (141W94) is extensively metabolized by P450 cytochromes, specifically, CYP3A4. Because hepatic insufficiency reduces P450-mediated metabolism, the concentrations in plasma of drugs metabolized through this pathway are often increased in subjects with liver disease. Following administration of a single, oral dose of 600 mg of amprenavir, pharmacokinetic parameters were determined for 10 subjects with severe cirrhosis, 10 subjects with moderate cirrhosis, and 10 healthy volunteers. Model-independent methods for determining the area under the plasma concentration-time curve (AUC) from time zero to infinity (AUC0–∞) showed an increase in amprenavir AUC0–∞ of 2.5-fold in the group with moderate cirrhosis and 4.5-fold in the group with severe cirrhosis compared with that in the control group of healthy volunteers (P < 0.05). AUC0–∞ was linearly related to the severity of liver disease, as assessed by the Child-Pugh score. Of the laboratory data used to calculate the Child-Pugh score, only the mean total bilirubin concentration showed a significant relationship with AUC0–∞. The relationship between the total bilirubin concentration and the AUC0–∞ of amprenavir was well characterized by a simple E max model, suggesting that the total bilirubin concentration may be a useful parameter for predicting the amprenavir AUC in subjects with hepatic insufficiency. Finally, the sera of cirrhotic subjects showed significant decreases in the levels of α1-acid glycoprotein, the primary plasma binding protein for amprenavir. On the basis of the results of this study, for an exposure equivalent to a clinical dose of 1,200 mg twice daily in subjects without cirrhosis, subjects with Child-Pugh scores of 5 to 8 should receive a twice-daily 450-mg dose of amprenavir, and subjects with Child-Pugh scores of 9 to 15 should receive a twice-daily 300-mg dose of amprenavir.

Modification of the DuPont aca as exemplified by a new procedure for neonatal total bilirubin.

1979 ◽  
Vol 25 (10) ◽  
pp. 1839-1841
Author(s):  
A D Fraser ◽  
A L Lindsay
Keyword(s):  
Spectrophotometric Method ◽  
Total Bilirubin ◽  
Serum Samples ◽  
Manual Method

Abstract Hemoglobin interferes with determination of total bilirubin by the diazo procedure with the DuPont aca. We compared results by that procedure with those by a manual direct spectrophotometric two-wavelength method. Because the manual method was not inhibited by hemolysis as was the DuPont aca diazo procedure, we reprogrammed our DuPont aca to measure the absorbance of diluted serum samples at 452 and 577 nm with use of DuPont absorbance packs as the sample pack and cuvette. Results correlated well with those by the manual spectrophotometric method, and hemolysis no longer interfered. The method is primarily intended for use with serum from neonates.

Serum Total Bilirubin Concentration Is Inversely Correlated with Framingham Risk Score in Koreans

2012 ◽  
Vol 43 (4) ◽  
pp. 288-293 ◽  
Author(s):  
Kwang-Min Kim ◽  
Bom-Taeck Kim ◽  
Sat-Byul Park ◽  
Doo-Yeoun Cho ◽  
Sang Hyeon Je ◽  
...  
Keyword(s):  
Risk Score ◽  
Framingham Risk Score ◽  
Total Bilirubin ◽  
Serum Total Bilirubin ◽  
Bilirubin Concentration ◽  
Framingham Risk ◽  
Total Bilirubin Concentration
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