What does a total bilirubin level of 0.20 mg/dL indicate in an adult?

Normal Total Bilirubin Level

A total bilirubin of 0.20 mg/dL is well below the normal upper limit of 1.2 mg/dL and indicates normal liver function and red blood cell turnover in an adult. 1, 2

Clinical Interpretation

• This value falls within the normal reference range for adults, where total bilirubin should typically be below 1.2 mg/dL 1, 2
• The level represents normal bilirubin metabolism, indicating proper hepatic conjugation and excretion of bilirubin, as well as normal hemoglobin breakdown from red blood cells 2, 3
• No further diagnostic workup or fractionation into direct and indirect bilirubin is necessary at this level 1

Emerging Evidence on Low Bilirubin

While this value is normal, recent research suggests that very low bilirubin levels (particularly <9 µmol/L or approximately <0.5 mg/dL) may have prognostic implications:

• Lower bilirubin concentrations have been associated with increased cardiovascular risk in certain populations, as bilirubin functions as an endogenous antioxidant protecting tissues from oxidative stress 4, 5, 6
• In elderly post-MI patients, bilirubin levels below 9 µmol/L (~0.5 mg/dL) were associated with a 52% increased risk of major adverse cardiovascular events compared to higher levels 5
• A 0.1 mg/dL increase in bilirubin level was associated with a 6% reduction in odds of peripheral arterial disease after adjusting for traditional risk factors 6

However, at 0.20 mg/dL, this value is still within the physiologically normal range and does not warrant concern or intervention. 2, 3

Clinical Context

• This bilirubin level provides no evidence of hemolysis, liver disease, or biliary obstruction 1, 2
• The value is consistent with normal hepatic synthetic function and normal red blood cell lifespan 2, 3
• No monitoring or follow-up is required based solely on this normal bilirubin value 1