Serum and urinary alpha-1 microglobulin levels in renal disease.

Serum and urinary levels of alpha 1-microglobulin (AM) were measured in healthy volunteers and patients with varying degrees of renal insufficiency (from mild impairment to functionally anephric patients). In all 33 healthy volunteers, 57 chronic renal disease and 22 functionally anephrics were studied. Serum creatinine (sCr) and 24-hour creatinine clearance (CCr) were used to assess renal function. Serum AM (SAM) increased with declining glomerular filtration and correlated well with CCr (r = -0.89, n = 90, P < 0.001) and sCr (r = 0.90, n = 112, P < 0.001). sAM increased faster than sCr as the filtration function diminished and may be a more sensitive indicator of impairment in renal glomerular filtration. Urinary AM (uAM) also increased as renal filtration decreased and the number of functional nephrons reduced. uAM correlated with sAM (r = 0.62, P < 0.001) and CCr (r = -0.50, P < 0.001). uAM had a higher percentage increase compared with sAM during the decline in renal function but was more poorly correlated with CCr or glomerular filtration function. It is concluded that AM is useful in assessing glomerular filtration function in addition to its well established relevance in tubular evaluation, and has potential in the longitudinal assessment of changes in renal function in renal disease and systemic diseases that affect the kidney.