Hypoproteinaemia is an abnormally low concentration of protein in the blood plasma — principally low albumin, the liver-made protein that maintains oncotic pressure and ferries hormones, drugs, and fatty acids. When albumin falls, fluid leaks from vessels into tissues: the swollen bellies and puffy faces of kwashiorkor, the oedema of nephrotic syndrome (protein lost in urine), and the wasting of chronic liver disease all trace to this single deficit. Causes divide into poor intake or absorption (starvation, gut disease), poor synthesis (liver failure), and excessive loss (kidney disease, burns, gut leakage). Treatment addresses the cause — feed, heal the liver, plug the leak — since infused albumin alone is a temporary patch.