Albumin Half-Life
The half-life of albumin in healthy individuals is approximately 20 days. 1
Physiological Parameters
Normal albumin half-life ranges from 14-20 days in healthy individuals, with 20 days being the most commonly cited value. 1
This extended half-life is regulated by the neonatal Fc receptor (FcRn), which protects albumin from intracellular degradation through active recycling mechanisms. 2, 3
Albumin is degraded at a constant fractional catabolic rate, with approximately 12 grams synthesized and degraded daily by the liver. 4
Structural Requirements for Normal Half-Life
An intact C-terminal end of albumin is absolutely required to maintain the 20-day half-life. 2
When the last C-terminal leucine residue (L585) is enzymatically cleaved by carboxypeptidase A, the half-life dramatically drops to only 3.5 days due to reduced FcRn binding. 2, 5
This structural requirement has critical implications for albumin-based therapeutics and explains why some patients may have unexpectedly short albumin half-lives. 2
Clinical Context: Comparison to Other Proteins
Prealbumin has a much shorter half-life of 2-3 days, making it more sensitive to acute nutritional changes than albumin. 1
Serum transferrin has an intermediate half-life of 8 days, falling between prealbumin and albumin. 1
Pathological Variations
Conditions that accelerate albumin turnover (hyperthyroidism, obesity, nephrotic syndrome) will shorten the effective half-life. 1
Conditions that decrease albumin turnover (hypothyroidism, liver cirrhosis) will prolong the effective half-life. 1
The fractional catabolic rate can be slowly reduced when serum albumin is markedly decreased in chronic diseases such as protein deficiency, cirrhosis, or nephrotic syndrome. 4
Implications for Glycemic Monitoring
Because of albumin's 14-20 day half-life, glycated albumin (GA) reflects glycemic control over approximately 2-3 weeks, specifically the preceding 1-2 weeks for a single measurement. 1
This makes albumin-based glycation markers more sensitive to short-term changes in glycemic control compared to hemoglobin A1c. 1