Monitoring of serum neopterin levels in renal transplant recipients: increased values during impaired renal function and cytomegalovirus infection.

In 92 renal transplant recipients, serum or plasma levels of neopterin were significantly elevated during pretransplant uremia, rejection, cyclosporin A induced nephrotoxicity and cytomegalovirus (CMV) infections. In patients with normal serum creatinine (less than 115 mumol/l) 71% had elevated serum neopterin levels. None of 19 cyclosporin A treated patients with stable renal function had a normal level of neopterin compared to 50% for patients treated with azathioprine (p less than 0.05). Due to the dependency on renal function the serum levels of neopterin could not distinguish between rejection and cyclosporin A induced nephrotoxicity. Marked increases in neopterin levels were seen during infections and especially during CMV infection. Determination of neopterin levels may be helpful in the diagnosis of CMV infection.