Albuminuria is more than the normal amount of albumin in the urine. Albumin is the main protein in human blood and it is the key to the regulation of the osmotic pressure of blood. Some albumin is normal in the urine. But too much albumin in the urine means that protein is leaking through the kidney, most often through the glomeruli. Albuminuria can mean many things. Thus, for example, albuminuria may be a sign of significant kidney disease or it may simply be a sequel of vigorous exercise. Albuminuria is a form of proteinuria.