Objective: To further analyse the significance and mutual relationship of thyroid function-linked alterations in cortisol metabolism that have been separately and variously reported.
Patients and measurements: Twenty-four-hour urine samples from 21 patients with hyperthyroidism (Graves' disease), 16 patients with hypothyroidism (Hashimoto's thyroiditis), 21 healthy age- and sex-matched controls for hyperthyroidism, and 16 healthy age- and sex-matched controls for hypothyroidism were evaluated for 6beta-hydroxycortisol (6beta-OHF), tetrahydrocortisol (THF), tetrahydrocortisone (THE), allo-tetrahydrocortisol (allo-THF), urinary free cortisol (UFF), urinary free cortisone (UFE) and 17-hydroxycorticosteroid (17-OHCS).
Results: Urinary 17-OHCS, THE and allo-THF levels increased considerably in hyperthyroid patients compared to the controls, while UFF and THF showed no difference between the two groups. Urinary 6beta-OHF was significantly lower in the hyperthyroid patients than in the controls. Both the urinary allo-THF + THF/THE and the UFF/UFE ratios were significantly lower in the hyperthyroid patients than in the controls, whereas only the former was significantly higher in the hypothyroid patients than in the controls. The urinary allo-THF/THF ratio was significantly higher in the hyperthyroid patients and significantly lower in the hypothyroid patients than in the controls. In an analysis of pooled subjects including all groups (n = 64), free T4 levels correlated negatively (P < 0.0001) with the urinary allo-THF + THF/THE ratio but not with the UFF/UFE ratio. The serum levels of free T4 correlated positively (P < 0.0001) with the urinary allo-THF/THF ratio.
Conclusion: The thyroid hormones seem to affect the total 11beta-HSD activity (allo-THF + THF/THE) more strongly than the renal 11beta-HSD2 activity (UFF/UFE). 5alpha-reductase activity (allo-THF/THF) is also enhanced in hyperthyroidism, while the reduction of urinary 6beta-OHF in hyperthyroidism might be a secondary effect of the altered activity of the total 11beta-HSD and 5alpha-reductase.