PRINCIPLE OF THE METHOD
Direct bilirubin (conjugated) couples with the diazo reagent in the
presence of sulfamic acid to form azobilirubin. The intensity of color
formed is proportional to the bilirubin concentration in the sample
tested. The increase of absorbance at 546 nm is directly proportional
to the direct bilirubin concentration.
CLINICAL SIGNIFICANCE
Bilirubin is caused by the degradation of hemoglobin and exists in two
forms. Unconjugated bilirubin is transported to the liver bound by
albumin where it becomes conjugated (direct) with glucuronic acid and
excreted.
Hyperbilirubinemia is the result of an increase of bilirubin in plasma.
Possible causes: Total bilirubin: Increase hemolysis, genetic,
neonatal jaundice, ineffective erythropoiesis and presence of drugs.
Direct bilirubin: Hepatic cholestasis, genetic, hepatocellular damage.
Clinical diagnosis should not be made based on a single test result; it
should integrate clinical and other laboratory data.
STORAGE AND STABILITY
The reagents are stable until the expiry date stated on the label when
stored at
2-8ºC, protected from light and contaminations are prevented during
their use. Do not use reagents over the expiration date.
Signs of reagent deterioration:
- Presence of particles and turbidity.
ADDITIONAL EQUIPMENT
- SPIN640 / SPIN640Plus Autoanalyzer.
- General laboratory equipment.
SAMPLES
Serum or plasma, free of hemolysis. Protect samples from light.
Stability of the sample: 4 days at 2-8ºC or 2 month at –20ºC.
QUALITY CONTROL
Control sera are recommended to monitor the performance of assay
procedures: SPINTROL H Normal and Pathologic (Ref. 1002120 and
1002210). If control values are found outside the defined range, check
the instrument, reagents and calibrator for problems.
Each laboratory should establish its own Quality Control scheme and
corrective actions if controls do not meet the acceptable tolerances.
