ISSN 1470-3947 (print) | ISSN 1479-6848 (online)

Endocrine Abstracts (2008) 16 P34

Renal excretion rates of free cortisol, free cortisone and dehydroepiandrosterone metabolites, but not renal indices of cortisol secretion are associated with urinary volume in healthy children

Lije Shi1, Stefan A Wudy2, Christiane Maser-Gluth3, Michaela F Hartmann2 & Thomas Remer1

1Research Institute of Child Nutrition, Dortmund, Germany; 2Steroid Research Unit, University of Giessen, Giessen, Germany; 3Department of Pharmacology, University of Heidelberg, Heidelberg, Germany.

Background: In experimental studies, a high fluid intake and a corresponding high urine volume have been shown to increase renal excretion rates of urinary free cortisol (UFF) and cortisone (UFE) in adults. We aimed to examine whether 24-h urinary steroid excretion rates are also affected by urine volume in children.

Methods: In 24-h urine samples of 100 prepubertal and 100 pubertal healthy children UFF, UFE, tetrahydrocortisol, 5α-tetrahydrocortisol, and tetrahydrocortisone were quantified by RIA. Urinary dehydroepiandrosterone and its 16α-hydroxylated downstream metabolites (DHEA&M) were analyzed along with the above three glucocorticoid tetrahydrometabolites using GC–MS in two additional groups of prepubertal (n=100) and pubertal (n=100) children. The sum of the 3 primarily glucuronidated tetrahydrometabolites (GC3) reflects daily cortisol secretion and DHEA&M represents an index of adrenarchal androgen secretion. Associations of urine volume with outcome variables UFF, UFE, GC3, and DHEA&M were examined in each developmental group using multiple regression models adjusted for sex, body weight, height, and total energy intake.

Results: Significant positive associations were observed between 24-h urine volume and UFF, UFE and DHEA&M in the respective prepupertal and pubertal groups with the highest explained variation for UFE, especially in puberty (R2=0.24). However, GC3 was not significant in any of the groups.

Conclusion: Urinary 24-h excretion rates of UFF, UFE, and DHEA&M, but not glucocorticoid secretion parameters are affected by daily urine volume in healthy free-living children. For a more specific assessment of associations of UFF, UFE, or DHEA&M with (patho)physiologically relevant factors, urine volume should be considered as a confounder.

This work was supported by a grant from European Chemical Industry Council (Cefic).

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