Albumin on Chemistry Panel: Concentration vs. Level
Albumin on a chemistry panel is reported as a concentration, specifically measured in grams per deciliter (g/dL) or grams per liter (g/L). 1
Technical Measurement Details
The term "concentration" is the scientifically accurate descriptor because:
- Albumin is quantified as mass per unit volume of serum or plasma, with normal ranges typically 3.5-5.0 g/dL by electrophoresis or 3.8-5.1 g/dL by the bromcresol green (BCG) method 1
- Most clinical laboratories use colorimetric methods (BCG or bromcresol purple) that measure albumin concentration, not simply presence or absence 1
- The measurement represents the amount of albumin protein dissolved in a specific volume of blood, which is the definition of concentration 1
Clinical Terminology Nuance
While "level" and "concentration" are often used interchangeably in clinical practice, the guidelines consistently refer to "serum albumin concentration" when discussing precise measurement:
- Guidelines from Gut explicitly state "serum albumin concentration" when describing its role as a marker of liver synthetic function 1
- The National Kidney Foundation guidelines specifically discuss "measurement of the serum albumin concentration" and reference "normal range" values in g/dL 1
- The term "level" is colloquially acceptable but technically less precise, as it doesn't specify the quantitative nature of the measurement 1
Practical Implications
Understanding this distinction matters because:
- Different assay methods (BCG vs. BCP vs. nephelometry) yield different concentration values, with BCG overestimating by approximately 0.61 g/dL in low ranges 1
- Concentration changes of even 0.1 g/dL can be clinically significant, particularly in chronic kidney disease where this correlates with 5-6% changes in mortality risk 2
- Reporting should specify both the concentration value AND the assay method used, as normal ranges vary by methodology 1