Serum levels of alpha-1 microglobulin in recipients of renal allografts.

Serum levels of alpha 1 microglobulin (s-alpha 1 m) in 92 recipients of renal transplants were elevated during pretransplant uremia (P less than 0.001), acute rejection (P less than 0.01), and cyclosporin-induced nephrotoxicity (P less than 0.01). In patients with stable renal function, those treated with cyclosporin had higher s-alpha 1 m than those receiving azathioprine: 81 +/- 4 and 64 +/- 3 mg/l (mean +/- SEM), respectively (P less than 0.05). The serum creatinine levels were 127 +/- 5 and 115 +/- 7 mumol/l (mean +/- SEM), respectively (N.S.). Two of the patients with normal serum creatinine had normal s-alpha 1m levels. There were positive linear correlations between s-alpha 1m and serum creatinine levels during stable renal function, rejection, cyclosporin-induced nephrotoxicity, and cytomegalovirus infections (r = 0.7-0.8, P less than 0.01-0.001) and between s-alpha 1m and beta 2 microglobulin (beta 2m) during the same conditions (r = 0.5-0.8, P less than 0.01-0.001). During infections, serum creatinine and beta 2m increased (P less than 0.001), but s-alpha 1m did not. S-alpha 1m values did not distinguish between rejection and cyclosporin-induced nephrotoxicity. It is concluded that s-alpha 1m might be a valuable complement to serum creatinine levels in the evaluation of renal function in renal transplant recipients.