Painless thyroiditis developed in a patient with Sheehan's syndrome.

We experienced an unusual combination of painless thyroiditis and Sheehan's syndrome in a single patient. A 29-year-old postpartum woman was referred to us for suspected Sheehan's syndrome. Endocrine tests confirmed the diagnosis, but, unexpectedly, her thyroid hormone levels in the plasma were elevated. Based on the data from various examinations on her thyroid including an extremely low uptake of radioactive iodine and spontaneous alterations of the thyroid function without any therapy for the thyroid, we diagnosed the patient as suffering from Sheehan's syndrome and painless thyroiditis simultaneously. Underlying mechanism(s) whereby painless thyroiditis occurred in our patient may be an immunological rebound after parturition, an immunological alteration induced by secondary hypoadrenocorticism, or a combination of these. The simultaneous occurrence of Sheehan's syndrome and painless thyroiditis is rare, as evidenced by the existence of only one similar case report in the literature. However, since neither Sheehan's syndrome nor painless thyroiditis is a rare endocrine disorder, the thyroid function of patients with postpartum hypopituitarism and previously diagnosed chronic thyroiditis should be carefully evaluated.