Diurnal leptin rhythms in children treated with prednisolone once daily in the morning or in the evening.

ABSTRACT

Serum leptin levels exhibit a marked diurnal variation in children. The aim of the present study was to investigate whether the timing of administration of exogenous glucocorticoids, which have been found to increase serum leptin, affects the diurnal rhythm. Four girls and four boys aged 10.6 to 15.8 (mean 13.2) years with asthma were studied. The design was an open 2-period cross-over trial with a 1-day run in, two 4-day periods of prednisolone 5 mg in the morning or in the evening, with a 3-week washout in between treatment periods. During run in and on the last day of the prednisolone periods a fasting blood sample was drawn at 08.00 h, and thereafter samples were obtained every 2 h throughout the day until 08.00 h the next morning. Serum leptin was measured by a specific radioimmunoassay. During all periods, leptin levels were low during the day with a nadir at 10.00 h (run-in [mean +/- SEM] 3.9+/-1.28; morning prednisolone 5.2+/-1.58; evening prednisolone 5.7+/-2.02 microg/l). Increases in leptin levels were detected from 20.00 h with zeniths at 24.00 h (run in 7.2+/-1.86; evening prednisolone 9.2+/-2.36 microg/l) and 02.00 h (morning prednisolone 9.4+/-1.78 microg/l) (F = 115.5; p <0.01). As compared to run in, leptin levels were increased at all time points during prednisolone treatment in the morning (F = 16.0, p = 0.01) and in the evening (F = 12.6, p = 0.01). No statistically significant differences were found in leptin levels during prednisolone in the morning or in the evening (F = 0.44, p = 0.53). Therefore, the timing of administration of exogenous glucocorticoids does not affect diurnal leptin rhythms in children.