Large-Amplitude Circadian Variations of Urinary Neopterin in Healthy Man

Abstract

Summary Urinary neopterin (Neo), a marker of T-cell activation was measured in five healthy males for a chronobiological study. Five young males mean age: 25 ± 2 (years ± SD) in apparent good health volunteered for the study. Total urine voidings were collected 4-hourly by each individual during a 48 h span at fixed clock hours. The study was carried out during 3 different 48 hours, one week apart. Neopterin was measured by HPLC and results were expressed as the ratio !lmol/mol creatinine.A statistically significant rhythm of neopterin was detected with a peak (Neo = 167.4 ± 33 .8 SD) at 06h30 and a trough (Neo = 110.9 ± 26.9) between 10h30 and 22h30. These results clearly show a 51 % total yariability of neopterin and must be kept in mind when assaying neopterin for clinical exploration. It is therefore imperative to use, in a given patient, the same time-qualified voidings (preferably the first morning one) in order to avoid misinterpretation in the follow-up of patients.