Serum and urine beta-2-microglobulin and lysozyme concentrations in transplant rejection.

We conclude that serum and urinary beta-2-microglobulin concentrations are useful in the diagnosis of acute and chronic renal transplant rejection. In acute transplant rejection, serum elevation in beta-2-microglobulins usually precede a rise in the serum creatinine. Increased urinary beta-2-microglobulin concentrations and elevated fractional excretion of beta-2-microglobulin occur in both acute and chronic transplant rejection. The finding of massive and sustained beta-2-microglobulinuria following acute rejection may herald recurrent clinical rejection episodes and eventual graft loss. Finally, serum and urine lysozyme levels appear to be less sensitive than the beta-2-microglobulins for diagnosing rejection and are often spuriously elevated in the presence of systemic or urinary tract infection.