Bilirubin Direct 164

Specimen collection & Preservation

Collect sample using standard sampling tube. Although serum is preferred, heparinized plasma or EDTA plasma can be used . Haemolysis interferes. Store samples protected from light as bilirubin is light sensitiv. Bilirubin in serum/plasma is stable for 1 day at 2-8 C and for 30 days at -20 C. Centrifuge samples containing precipitate before performing assay .

Calculations 

• Fully automated system automatically calculated the bilirubin concentration of each samples.
• Results in mmol/l= Result in mg/dl x 17.1

Application Sheet 

Refer to the application sheet for details. For additional system applications, contact our local accurex representative.

Calibration

 For calibration , it is recommended to use C.F a.s or any other suitable calibrator material.

Calibration frequency  

Re- calibration is recommended 

• Whenever the reagent lot is changed .
• As per the requirement of quality control procedured.

Note: 

Expected range varies from population to population. it is therefore recommended that each laboratory should establish its own normal range. For diagnostic purposes, the bilirubin results should always be assessed in diagnostic purposes, the bilirubin results should always be assessed in conjuction with the patients medical history clinical examinations and other findings.

Performance Characteristics 

Linearity 

With Autopure Bilirubin , the assay is linear up to 20 mg/dl (342 mmol/l).Determine samples with higher concentration via the rerun function . On instrument without rerun function, manually dilute samples with higher concentration using 0.9% NaCl or distilled/deionized water (e.g. 1+3 ). Multiply the result by the appropriate dilution factor (e.g. 4).

Interference

 Haemolysis interferes in samples from adults. Occasionally , slighty higher values for direct bilirubin than for total bilirubin may be yielded by samples in which the totl and direct bilirubin concentrations are similar. In such samples, the bilirubin concentration determined by both methods should be stated.

 Co- Relation Studies

A comparison of the bilirubin determination using autopure bilirubin and reference competitors bilirubin reagent gave the following co- realtion (mg/dl):

Linear Regression

                                  Total

y=                             0.974x +0.101 

r=                             0.9995

Sy.x=                      0.22

No of samples measured :15

The samples concentrations measured were between:

Total :0.70 mg/dl and 20.0 mg/dl

Direct : 0.40 mg/dl and 8.70 mg/dl

References

•  Tietz N.W. ed. clinical guide to laboratory tests, 3rd ed. philadelphia pa :W.B. Saunders, 1995:88.
• Malloy HT, Evelyn KA. The determination of bilirubin with the photoelectric colorimeter.JBiol. chem 1937;119 : 481-490.
• Wahlefeld AW, Herz G , Bernt E. Modification of the Malloy- Evelyn method for a samples, reliable determination of total bilirubin in serum scand.j clin. lab . invest 1972;29 supplement 126:Abstract 11.12.
• Pearlman, P.C & Lee, R.T Clin. Chem 20 :447 (1974)
• Henry , rj (ed.) clinical chemistry : principal and teachniques (2nd ed) Harper and pow p 1042 (1979)
• Jendrassik L & Grof P . bIOCHEM 2.297 ,81 (1938)
• Practical clinincal biochem.vol 1, 5 th ed. H Varley,p 1012 (1980)