Case report: Myxedema psychosis caused by subclinical hypothyroidism

Abstract

Acute psychosis is a rare but possible clinical manifestation of hypothyroidism. Often referred to as myxedema psychosis, it is less frequently reported in the subclinical form of hypothyroidism compared to the clinical form, and rarely presents as its first manifestation, in the absence of any physical symptoms or signs. Our case report concerns a 46-year-old woman, with a medical history of a total thyroidectomy and irregular adherence to thyroxine treatment, who presented with a first-episode psychosis of subacute onset dominated by persecutory delusional ideas, formal thought disorder and emotional lability, without evident hypothyroidism signs or symptoms. Investigations revealed an elevated thyroid-stimulating hormone (TSH) and a normal free T4 (FT4). Other medical causes of acute psychosis were excluded, and the diagnosis of psychosis associated with subclinical hypothyroidism was assumed. Treatment with oral levothyroxine combined with olanzapine was initiated, leading to a rapid improvement, with complete remission of symptoms after ten days, concurrently with a gradual normalization of thyroid function. Antipsychotic treatment was suspended three months after discharge, with maintained remission of psychotic symptoms during the two-year follow-up. This clinical case highlights the importance of considering hypothyroidism in the differential diagnosis of a first-episode psychosis, even in the subclinical form and in the absence of physical signs or symptoms. The hormonal replacement therapy, combined or not with antipsychotic medication, leads to excellent prognosis in the majority of cases.