[Neopterin in the serum and urine in the differential diagnosis of disorders of kidney function following kidney transplantation].

In a period of 10 months neopterin in serum and urine was determined by radioimmunoassay in 33 renal allograft recipients treated with cyclosporin A. While in allograft rejections the highest neopterin concentrations were found in the serum, patients with viral infections after renal transplantation showed the most elevated concentrations in the urine. For early diagnosis of allograft rejection the ratio of neopterin clearance and serum-neopterin was the most significant criterion of the parameters measured in this study. Patients without complications during the follow-up showed slightly elevated and stable neopterin levels in serum and urine. The presented results indicate that neopterin is a useful parameter for the follow-up after renal allograft transplantation and for the diagnosis of immunological complications.