Comparison of serum neopterin levels and urinary neopterin excretion in renal allograft recipients.

Determination of serum and urinary neopterin levels was performed daily in 30 patients undergoing kidney transplantation for treatment of end-stage renal failure. Neopterin serum levels were determined by RIA and urinary excretion by HPLC. In parallel, the same samples were tested for creatinine content. Results indicated a strong correlation between the clearance of neopterin and creatinine. This correlation was independent of the extent of functional impairment as well as of the different causes of renal insufficiency. As a consequence, a strong relationship between serum and urinary neopterin levels was only obtained when values were corrected for different renal function by dividing them by the creatinine levels. It thus appears that major attention has to be paid to the functional state of the kidney when studying neopterin serum and/or urine values. It also appears that under these prerequisites both methods of detection as well as both sample sources yield comparable results.