The effect of iatrogenic subclinical hyperthyroidism on anxiety, depression and quality of life in differentiated thyroid carcinoma

Overt thyroidism is known to cause neuropsychiatric disorders but studies on subclinical hyperthyroidism (SCH) are limited. Subclinical hyperthyroidism induction by administering L-Thyroxine (LT4) is the standard treatment method in differentiated thyroid carcinoma (DTC) follow-up. Our aim was to investigate whether anxiety, depression and quality of life are affected in DTC patients followed-up with exogenous SCH. The patients were divided into exogenous SCH by LT4-DTC (n = 127), euthyroid-DTC (n = 66) and exogenous euthyroid-benign thyroid noduüle (BTN) who underwent thyroidectomy for benign thyroid pathology (n = 85) groups. The rate of moderate/severe anxiety was significantly higher in SCH-DTC than euthyroid-BTN group (27.5%, n = 35 vs. 9.4%, n = 8) (P = 0.001). TSH levels and Beck anxiety inventory (BAI) scores were significantly negatively correlated(P = 0.009 r = –0.16). Free T4 and BAI were significantly positively correlated (P = 0.04 r = 0.4). The groups were similar in terms of depression severity (P = 0.15). Subclinical hyperthyroid-DTC group scored significantly lowerthan euthyroid-BTN group in all scales of SF-36 quality of life survey. LT4-induced SCH, which is a part of traditional DTC treatment, can exacerbate the anxiety symptoms in patients and disrupt their quality of life, depending on the level of fT4.