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

Endocrine Abstracts (2008) 16 P35

Glucocorticoids and body fat are associated with urinary excretion rates of uric acid and oxalate, but not of calcium in healthy children

Lijie Shi1, Shoma Berkemeyer1, Annette Buyken1, Christiane Maser-Gluth2 & Thomas Remer1

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

Background: In patients with hypercortisolism, who are frequently obese, the prevalence of urolithiasis is increased and urinary excretion rates of calcium (Ca), oxalate (Ox), and uric acid (UA) are regularly elevated. In the present study, we examined whether these lithogenic factors are already associated with dietary intakes, body fat, and cortisol metabolites in free-living children.

Methods: In 24-h urine samples of healthy children (150 boys, 150 girls, aged 4–14 years) urinary free cortisol (UFF), cortisone (UFE), the sum of 3 major glucocorticoid metabolites (GC3) as well as Ca, Ox, UA and net acid excretion (NAE) were determined cross-sectionally along with relevant nutritional and anthropometric parameters. Potentially-bioactive-free-glucocorticoids were assessed as UFF+UFE and adrenal glucocorticoid secretion as GC3. Associations of diet, percent body fat (%BF) and glucocorticoids with outcome variables were examined in multiple regression models adjusted for sex, age, height, growth velocity and total energy intake.

Results: Positive associations with the urinary outcomes Ca, Ox, and UA were observed for the nutritional factors Ca, fiber, and protein intake, respectively, for sodium intake (outcomes: Ca, UA), and for the indicator of dietary acid load NAE (outcomes: Ca, Ox, UA). %BF and cortisol secretion (GC3) were both positive predictors of UA and Ox. Of all dietary and hormonal variables, UFF+UFE explained most of the variation (partial R2=0.08, P<0.0001) of urinary UA and also part of the variation of Ox (partial R2=0.02, P<0.05), but none of Ca.

Conclusion: Apart from the known nutritional determinants, such as protein and sodium intake, also dietary acid load and increased body fatness appear to affect urinary Ca, Ox and UA. Additionally, higher potentially-bioactive-free-glucocorticoids, even in the physiological range, may contribute to stone forming risk via elevations in UA and Ox, but not Ca.

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