Albumin

What is Albumin?

Albumin is the most abundant protein in blood plasma — accounting for around 60% of all plasma proteins — and is produced almost exclusively by the liver. It has two primary functions: maintaining the colloid osmotic pressure (which determines how much fluid stays inside blood vessels rather than leaking into surrounding tissue) and transporting a wide range of substances through the bloodstream, including hormones, fatty acids, calcium, bilirubin, and drugs. Dutch labs report albumin in g/L; internationally also in g/dL (1 g/dL = 10 g/L). Reference ranges for adults are typically around 35–52 g/L, but always check the bounds your own laboratory reports. Albumin is a negative acute-phase protein: during inflammation, trauma, infection, or chronic illness, albumin falls — not because the liver is failing, but because the liver prioritises production of acute-phase proteins such as CRP instead. A low albumin therefore reflects both reduced liver synthetic function and systemic stress, undernutrition, or serious illness elsewhere. That non-specificity makes context indispensable.

Why is Albumin relevant?

Albumin is a useful routine marker for several reasons. First, it is a sensitive indicator of liver synthetic function: with serious hepatocyte loss — as in cirrhosis or chronic liver failure — albumin falls because the liver lacks production capacity. Its half-life of roughly twenty days means it only falls once damage has been sustained for some time, making it less useful as an early marker but highly informative for chronic liver synthetic reserve. Second, a low albumin is a classic signal of undernutrition or chronic protein loss. In nephrotic syndrome albumin leaks through the urine; in protein-losing enteropathy through the gut. For anyone chronically ill, recovering from major surgery, or with significantly reduced appetite, albumin directly reflects protein reserves and nutritional status. Third, albumin binds calcium in the blood: low albumin makes total calcium look artificially low even when physiologically active free calcium is normal. Corrected calcium adjusts for this.

Albumin high or low — what it means

A low albumin is best read alongside liver enzymes (ALT, AST, bilirubin, GGT), kidney markers (creatinine, eGFR, urinary protein), CRP, and the clinical picture. When active inflammation is present (raised CRP), albumin already falls as part of the acute-phase response — how low albumin is relative to the inflammatory signal helps indicate whether a synthesis or loss component is also at play. In chronic liver disease, albumin is part of scoring systems such as Child-Pugh and MELD-Na that quantify the severity of cirrhosis. An albumin below 30 g/L is an alarm threshold suggesting severe loss of liver synthetic capacity or chronic loss. Values between 30 and 35 g/L always need context — they fit an acute infection just as readily as early liver disease or undernutrition. A high albumin is uncommon and usually reflects dehydration (relative concentration rise); for a fair reading, measure albumin when well hydrated.

Educational information only — not medical advice. Consult a healthcare professional for clinical decisions.