Albumin, with a relative molecular weight of 66 KDa, is the major protein in human plasma. In the urine, under normal physiologi- cal conditions, albumin is present at very low concentrations.
Presence of increased quantities of protein in the urine is an important predictor of progressive kidney damage. Proteinuria is preceded by a period of minor increased urinary albumin excretion (30 to 300 µg/day) not detected by routine methods. This period, designated as microalbuminuria, is a marker of both renal and cardiovascular disease. If microalbuminuria remains undetected, it leads to subsequent development of diabetic nephropathy and irreversible kidney failure. Thus, in order to detect minimal renal impairment and to control its progression a sensitive method of measuring minor increases in urinaryalbumin is of great importance
Although testing for microalbuminuria is primarily indicated in diabetes mellitus, it has also been used in studies of hyperten- sion, pregnancy, non-diabetic renal disease and for renal effects of various drugs, hormones, and nephrotoxins. Urinary tract infections and congestive heart disease are also possible causes of elevations in the albumin excretion rate.