Urinary cortisol metabolites in the assessment of peripheral thyroid hormone action: application for diagnosis of resistance to thyroid hormone

Abstract

Urinary cortisol metabolites are altered both quantitatively and qualitatively in thyroid dysfunction. This study was conducted to elucidate the usefulness of urinary cortisol metabolites in the assessment of peripheral thyroid hormone action, particularly in the patients with inappropriate thyrotropin secretion. Twenty-four hour urinary 17-hydroxycorticosteroid (17-OHCS) level and gas chromatographical steroid profile were studied in 25 hyperthyroid, 18 hypothyroid, and 24 euthyroid control subjects. Five patients with generalized thyroid hormone resistance and two patients with thyrotropin secreting pituitary tumor were also studied. The ratio of urinary tetrahydrocortisone to tetrahydrocortisol (THE/THF) was significantly elevated in hyperthyroidism (4.58 +/- 1.49) and depressed in hypothyroidism (1.31 +/- 0.55) compared to control (1.93 +/- 0.35). There were good correlations between THE/THF and serum thyroid hormone levels, especially in hypothyroidism. THE/THF can be a good biochemical indicator for deficiency of peripheral thyroid hormone action. Two patients with thyrotropin-secreting tumor showed high THE/THF, which reflected thyroid hormone excess. In contrast, THE/THF in the patients with generalized thyroid hormone resistance was low as compared to high serum thyroid hormone levels. Similar findings were demonstrated with 17-OHCS but discrimination of thyroid hormone resistance was insufficient. Thus, the ratio of the urinary concentrations of cortisol metabolites, THE/THF, appears to be a good marker for peripheral thyroid hormone resistance.