Hirata Syndrome in a Woman With Graves' Disease Without Exposure to Thionamides and Summary of Cases from South America.

We report here the third case of Hirata syndrome from Peru, a 65-year-old woman who presented to the emergency room with obtunded sensorium caused by severe hypoglycemia secondary to endogenous autoimmune hyperinsulinism after 1 year of many episodes of postprandial hypoglycemia. Six months before admission, both arterial hypertension and Graves' disease were disclosed, receiving nebivolol 5 mg day only. Eight days before admission, flavonoids were prescribed for mild venous insufficiency. Treatment of hypoglycemia included drug withdrawal, a fractionated diet with low-glycemic index carbohydrates, prednisone, and radioactive iodine for definitive treatment of Graves' disease, with resolution of the condition 6 months later. She presented unilateral avascular necrosis of the hip as a complication of corticosteroid therapy. We did not identify any trigger factor for hypoglycemia besides Graves' disease as she did not receive any drug at hypoglycemia onset. We recommend checking for anti-insulin antibodies in cases of endogenous hyperinsulinism associated with an autoimmune disease, despite the absence of any drug treatment.