The age of patients with thyrotoxicosis factitia in Italy from 1973 to 1996

Abstract

Thyrotoxicosis factitia, a syndrome due to the surreptitious ingestion of excess thyroid hormones, has generally been diagnosed in young or middle-aged women with psychopathological disturbances. We reviewed all the cases seen at our Institution over a 24-yr period, from 1973 to 1996. All 25 patients were women. Analysis was restricted to 17 patients who were born and lived in Tuscany (our region), since only these patients were distributed during the whole observation period. Diagnosis of thyrotoxicosis factitia was based on the following parameters: elevated serum total and/or free thyroid hormone levels, undetectable serum thyrotropin levels, low/undetectable serum thyroglobulin concentration, normal urinary iodine excretion, low/suppressed thyroidal radioactive iodine uptake (RAIU), absence of goiter, absence of circulating anti-thyroid antibodies. Surreptitious ingestion of thyroid hormone pill was eventually admitted by all patients. Age at diagnosis was >50 yr in 7/17 patients (41%): 6 of them were distributed in the period 1995-1996, and one in 1988. Patients older than 60 yr were 5/17 (29%), all in the last two years of the period under investigation. There was an increase in the age of patients with thyrotoxicosis factitia (p=0.02), which lost a statistical significance when the patients of the 1995-1996 period were excluded from analysis (p=0.88). This study provides evidence of an increased age of patients with thyrotoxicosis factitia in more recent years. From a practical standpoint, our study suggests that thyrotoxicosis factitia should be suspected and adequately looked for even in old patients with thyrotoxicosis of inexplicable origin, especially in the absence of goiter and thyroid autoimmune phenomena, and when common causes of low- RAlU hyperthyroidism, such as a load with iodine- containing drugs or subacute thyroiditis, have been excluded.