What is Urine Albumin?
Albumin is a plasma protein synthesised exclusively by the liver. The glomerular filtration barrier normally restricts albumin passage on the basis of size and negative charge; the small amount that crosses is largely reabsorbed by proximal tubular cells. When glomerular permeability rises or tubular reabsorption falls, urinary albumin excretion increases, providing a sensitive index of early kidney damage before the glomerular filtration rate declines measurably.