Normal Serum Albumin Concentration
The normal serum albumin concentration in healthy adults is 3.5-5.0 g/dL when measured 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
Method-Specific Reference Ranges
The normal range varies depending on the laboratory method used:
- Electrophoretic method (gold standard): 3.5-5.0 g/dL 2, 1
- Bromcresol green (BCG) method (most common): 3.8-5.1 g/dL 2, 1
- Bromcresol purple (BCP) method: Use laboratory-specific reference ranges, as this method underestimates albumin by approximately 0.71 g/dL compared to more accurate methods 2, 1
Critical Laboratory Considerations
Always confirm which assay method your laboratory uses, as different methods have different reference ranges and clinical reliability. 1
- The BCG method is rapid, reproducible, automated, and preferred when available 2
- BCG 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 2, 1
- The BCP method has proven less reliable clinically and underestimates values by approximately 19% in dialysis patients 2, 1
- If BCP must be used, rely on that laboratory's specific reference range and place less clinical weight on the absolute values 2, 1
Clinical Significance of Values
Values below 3.5 g/dL are considered hypoalbuminemia and indicate malnutrition or other pathology. 3
- A decline in albumin by ≥0.3 g/dL to <4.0 g/dL indicates nutritional deterioration in chronic kidney disease patients 2
- Even small decreases of 0.1 g/dL are clinically significant and associated with a 5% change in risk of technique failure, 5% change in days hospitalized, and 6% change in risk of death in peritoneal dialysis patients 4
- Hypoalbuminemia (<3.5 g/dL) is associated with significantly increased mortality, longer hospital stays, and higher complication rates across multiple patient populations 3, 5, 6, 7
Common Pitfalls to Avoid
- Do not assume all laboratories use the same method or reference range - always verify the specific assay being used 2, 1
- Do not dismiss small but progressive decreases in albumin levels - even changes of 0.1 g/dL are clinically meaningful 4
- Do not overlook pre-analytical factors such as prolonged tourniquet application during blood draw, which can cause hemoconcentration and falsely elevated values 1
- Do not ignore values in the "low-normal" range - the highest albumin level possible should be the goal for each patient, and a stable or rising concentration is more desirable than a declining one, even if both are within normal range 4