Thyroid function in idiopathic oedema.

Abstract

The role of abnormal thyroid function in the aetiology of idiopathic oedema is unclear. Previous studies of small samples of patients have suggested a high prevalence of latent hypothyroidism and a possible deiodination defect in the conversion of T4 to T3 in this condition. There is a need to clarify the possible significance of abnormal thyroid function in a larger sample of idiopathic oedema patients. The study was undertaken to compare basal thyroid function in idiopathic oedema patients and in an age and sex-matched control group. After excluding one idiopathic oedema patient and three control subjects with abnormal thyroid function, basal thyroid function was compared in 44 idiopathic oedema patients and in 44 age and sex-matched controls. Basal thyroid function was assessed in patient and control groups by measuring serum T4, fT4, T3, fT3 and TSH by standard methods. There were no significant differences in basal thyroid function between patient and control groups except for an elevated mean fT4 concentration in the idiopathic oedema group (P = 0.03). Exclusion of patients and controls taking oestrogen abolished this difference. T4:T3 ratios were similar in patient and control groups. Abnormalities of basal thyroid function are uncommon in patients with idiopathic oedema and appear unrelated to the pathogenesis of this disorder. Similar T4:T3 ratios between patient and control groups exclude a deiodination defect in idiopathic oedema.