lazy adrenals in severe hypothyroidism - myth or mirage?

Background: clinical features of hypothyroidism and adrenal insufficiency (ai) often overlap. objectives: to assess the morning serum cortisol levels of treatment-naïve patients with severe hypothyroidism. methods: in this prospective, case-control study, treatment-naïve adults with severe hypothyroidism [thyroid-stimulating hormone (tsh) > 100 miu/ml] were compared with age- and sex-matched euthyroid controls. morning (08:00 am) serum cortisol, tsh, triiodothyronine (t3), and thyroxine (t4) levels were measured. ai was defined clinically and biochemically as cortisol levels < 4 µg/dl. correlation coefficients between t3, t4, and cortisol levels were calculated. results: the case group (n = 71; women, 88.7%; mean age, 30.0 ± 9.0 years) had significantly lower serum cortisol levels than controls (n = 40; 8.6 ± 4.2 vs 16.0 ± 2.22 µg/dl; p < 0.0001). six patients (8.5%) in the case group met criteria for ai. patients with ai had significantly lower t3 and t4 levels than those without ai (p = 0.018 and p = 0.005, respectively). a negative correlation was observed between t3 and cortisol levels (r = -0.243, p = 0.041), while t4 showed no significant correlation (r = -0.103, p = 0.391). conclusions: treatment-naïve patients with severe hypothyroidism may exhibit biochemical evidence of ai. routine screening for ai in these patients is recommended to avoid missed diagnoses and guide appropriate therapy.