Evaluation of Hyperbilirubinemia: Albumin vs Microalbumin Testing
When evaluating hyperbilirubinemia, you should test serum albumin (not microalbumin), as albumin is a marker of hepatic synthetic function and is essential for assessing liver disease severity. 1
Why Albumin, Not Microalbumin
- Albumin is produced exclusively by the liver and serves as a key indicator of hepatic synthetic capacity in patients with elevated bilirubin 1
- Microalbumin testing is specifically designed for detecting early diabetic nephropathy and has no role in the evaluation of liver disease or hyperbilirubinemia 1
- Microalbumin refers to urinary albumin excretion (30-299 mg/g creatinine) used to screen for kidney damage in diabetic patients, not serum albumin levels 1
Essential Laboratory Panel for Hyperbilirubinemia
When hyperbilirubinemia is identified, obtain the following tests 1, 2:
- Fractionated bilirubin (conjugated vs unconjugated) to determine the etiology 1, 2
- Serum albumin to assess hepatic synthetic function 1
- Prothrombin time (PT)/INR as another marker of synthetic function 1, 2
- ALT, AST, alkaline phosphatase, and GGT to characterize the pattern of liver injury 1, 2
- Complete blood count with peripheral smear to evaluate for hemolysis 2
Clinical Significance of Albumin in Liver Disease
- Serum albumin concentrations decrease in advanced liver disease when there is significant loss of synthetic function (typically >70% loss) 1
- However, albumin levels can be reduced in many non-hepatic conditions including sepsis, systemic inflammation, nephrotic syndrome, malabsorption, and gastrointestinal protein loss 1
- Bilirubin binds to albumin in the circulation, and this protein-bound fraction becomes clinically important in hepatocellular and cholestatic jaundice 3
Common Pitfall to Avoid
Do not order microalbumin testing when evaluating hyperbilirubinemia. This is a completely different test used exclusively for diabetic nephropathy screening 1. The confusion likely arises from the similar terminology, but these tests serve entirely different clinical purposes and patient populations.
Interpretation Context
- In patients with conjugated hyperbilirubinemia and low albumin, this suggests significant hepatic dysfunction and warrants urgent evaluation for liver disease 1, 2
- In patients with unconjugated hyperbilirubinemia and normal albumin, Gilbert's syndrome is most likely, requiring no treatment 1, 2
- Albumin <3.5 g/dL with elevated bilirubin indicates impaired hepatic synthetic function and should prompt assessment for cirrhosis or acute liver failure 1