Normal Range for Serum Albumin
The normal range for serum albumin is 3.5-5.0 g/dL by electrophoretic methods, or 3.8-5.1 g/dL when measured by the bromcresol green (BCG) colorimetric method, which is the most commonly used laboratory assay. 1, 2
Method-Specific Reference Ranges
The normal range varies depending on the laboratory assay used:
- Electrophoretic method (gold standard): 3.5-5.0 g/dL 1
- Bromcresol green (BCG) method (most common): 3.8-5.1 g/dL 1
- Bromcresol purple (BCP) method: Use laboratory-specific reference range, as this method tends to underestimate albumin levels by approximately 0.71 g/dL compared to more accurate methods 1
Clinical Significance of the Range
Values below 4.0 g/dL, even within the "normal" range, carry prognostic significance:
- Serum albumin <4.0 g/dL is associated with increased short-term and long-term mortality in hospitalized patients, even though it falls within the traditional normal range 3, 4
- A decline in albumin by ≥0.3 g/dL to <4.0 g/dL indicates nutritional deterioration in chronic kidney disease patients 1
- Albumin levels in the low-normal range (≤4.3 g/dL) are associated with more rapid decline in kidney function compared to levels ≥4.7 g/dL 5
- In cirrhosis patients receiving albumin therapy, achieving on-treatment levels of 4.0 g/dL or higher is associated with improved survival 6
Important Laboratory Considerations
Always verify which assay method your laboratory uses, as this affects interpretation:
- The BCG method overestimates albumin in the low range by approximately 0.61 g/dL on average, and differs from electrophoretic methods by about 0.3 g/dL 1
- BCG is preferred over BCP when available, as BCP has proven less reliable clinically and underestimates values by approximately 19% in dialysis patients 1
- If BCP must be used, rely on that laboratory's specific reference range and place less clinical weight on the absolute values 1
Common Pitfalls to Avoid
Do not assume all values within the "normal" range are clinically equivalent:
- Values at the lower end of normal (3.5-3.9 g/dL) carry significantly higher mortality risk than values at the upper end (≥4.5 g/dL) in hospitalized patients 3, 4
- Pre-analytical factors can falsely elevate albumin: prolonged tourniquet application during blood draw causes hemoconcentration 2
- Dehydration is the most common cause of elevated albumin above the normal range, representing concentrated plasma rather than true hyperalbuminemia 2
- Always confirm the laboratory method being used, as different assays have different reference ranges and clinical reliability 1