Thyroid diseases in patients with active endogenous Cushing’s syndrome

Abstract

Objective: Data about the impact of Cushing’s syndrome (CS) on thyroid is scarce. We aimed to identify the prevalence of thyroid diseases in patients with CS. Patients and Methods: Nineteen patients with CS and 40 healthy participants were included in the study. All patients were tested for free tri-iodothyronine (fT3), free thyroxine (fT4), thyroid-stimulating hormone (TSH), anti-thyroglobulin (anti-Tg), and antithyroid peroxidase (anti-TPO) levels, and thyroid ultrasonography (US). Results: Overt hypothyroidism, subclinical hypothyroidism, and subclinical hyperthyroidism was evident in 5.3%, 5.3%, and 21.1% of patients with CS; and 2.5%, 7.5%, and 15% of healthy subjects, respectively. fT3 and fT4 levels were lower in patients with CS. None of the patients with CS and 27.5% of the control group had autoimmune thyroid disease (AITD), which was demonstrated by both US findings and anti-TPO positivity (P=0.01). Frequency of thyroid nodule was 52.6% and 52.5% in patients with CS and controls, respectively (P=0.99). Conclusion: The prevalence of thyroid dysfunction, nodular thyroid disease, and goiter is comparable to healthy population. However, AITD is less prevalent among patients with CS. Although, hypercortisolism has an impact on hypothalamic-hypophyseal-thyroid axis, its clinical implication does not seem to be significant.