Endocrine Abstracts

Both thyroid dysfunction and psychological morbidity are common in the general population. Association between mood disorders and overt thyroid dysfunction are well established. Hypothyroid patients are more prone to depression and anxiety is a frequently reported symptom in thyrotoxicosis. However, the relationship between thyroid hormones in the normal range and psychological well being has not been established.

In this study we analysed the relationship between psychological wellbeing and thyroid hormones (thyroxine – T4, triiodothyronine – T3, thyrotropin – TSH, reverse triiodothyronine – rT3) in 697 patients who were on a stable dose of thyroxine replacement as part of the baseline assessment of a randomized controlled trial of T3/T4 therapy. Psychological well being was assessed by the General Health Questionnaire – 12 (GHQ-12). A Higher GHQ-12 score indicated increased psychological morbidity. Local ethical committee approval was obtained.

All the patients were euthyroid on thyroxine (median TSH – 0.9 mU/L, mean free T4 – 20.98 pmol/L and mean free T3 – 3.85 pmol/L). While fT4 showed a strong correlation to the GHQ-12 scores (b: −0.16, P=0.005), the correlation with TSH was weak (b: 0.663, P=0.04) and no correlation was seen with fT3 and rT3 (fT3 – b:0.32, P=0.28; rT3 – b:0.09, P=0.95). In addition, there was no correlation seen between the GHQ scores and rT3/T3 & T4/rT3 ratios.

We conclude that free T4 concentrations may predispose to psychological morbidity even within the reference range in treated hypothyroid patients. However, the relationship of thyroid hormones and the mood in patients without thyroid dysfunction remains to be established.