Chapter 5 100 Twenty-four-hour urinary cortisol, cortisone and their metabolites Effects on 24-h urinary excretions of cortisol, cortisone, and their metabolites are presented in Table 3. After 24-wk of magnesium supplementation, 24-h urinary cortisol excretion showed a mean decrease of 32 nmol/24-h in the magnesium group (95% CI: -59; -5 nmol/24-h, P=0.021). Mean 24-h urinary THF and allo-THF excretions were not significantly different between the groups after 24-wk (-0.5 μmol/24-h, 95% CI: -1.2; 0.3 μmol/24-h, P=0.231 and -0.5 μmol/24-h , 95% CI:-1.1; -0.0 μmol/24-h, P=0.065, respectively) as compared with the placebo group. Oral magnesium supplementation did not change 24-h urinary cortisone and THE excretions after 24-wk (-1 nmol/24-h, 95% CI: -38; 35 nmol/24-h, P=0.949 and -0.2 μmol/24-h, 95% CI: -1.9; 1.6 μmol/24-h, P=0.861, respectively). No significant effect on the total secretion was found (-1.2 μmol/24-h, 95% CI: -4.0; 1.7 μmol/24-h, P=0.420). Additionally, analyses using logtransformed data were performed, but similar effects on cortisol, cortisone and their metabolites were observed (Table 4). Enzyme activity of 11β-HSDs and A-ring reductases Effects of magnesium supplementation on enzymatic activities of 11β-HSDs and A-ring reductases are shown in Table 3. The cortisol/cortisone ratio, which reflects the kidney 11β-HSD type 2 activity, was lower after 24-wk in the magnesium group (-0.10 nmol/nmol, 95% CI: -0.17; -0.03 nmol/nmol, P=0.005) as compared with the placebo group. Furthermore, the THFs/THE ratio, which reflects the overall measure of 11β-HSD activity, was decreased by 0.09 μmol/μmol (95% CI: 0.02; 0.17 μmol/μmol, P=0.018) following magnesium supplementation. No difference in THF/allo-THF ratio, as index for 5α- and 5β-reductase activity, was observed between the groups. The ratio allo-THF/cortisol, as index for 5α -reductase activity, and the ratios THF/cortisol and THE/cortisone reflecting 5β-reductase activity did also not differ. Finally, no effects of magnesium supplementation on enzyme activities of A-ring reductases were found when we performed the analyses with log-transformed data (Table 4).
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