High repeatability of circadian prolactin rhythm assessment results in children.

OBJECTIVES: In normal conditions, prolactin (Prl) secretion manifests a circadian pattern. So far, there have only been but few studies, concerning intrasubject variability and repeatability of the circadian Prl secretion pattern, based on pulse analysis. It seems, that macroscopic analysis based on measurement of Prl concentration at nine time points every 3 hours during 24 hours is an appropriate method to assess Prl profile for clinical purposes. The aim of the study was to assess the repeatability of that circadian Prl secretion pattern in a group of short children without hormonal disorders.

MATERIALS AND METHODS: The analysis comprised the results of two circadian Prl profiles, performed from 2 to 14 months in 23 prepubertal children (16 boys) with idiopathic short stature, aged: 10.3+/-2.4 yrs.

RESULTS: There were no statistical differences between Prl concentrations at the same time points in the two consecutive profiles, but the comparison of Prl concentrations at 8:00 gave results which were close to the border of statistical significance (p=0.055), what indicated low repeatability of measurement results at that particular time point. There were no statistical differences between the values of particular parameters in macroscopic profile analysis in the first and in the second test.

CONCLUSION: Circadian Prl profile, based on nine Prl concentration measurements, taken every 3 hours during one day, is characterized by high repeatability of the results and low intrasubject variability in children, despite the results of Prl concentration at 08:00 o'clock.