Thyroid Research Centre, Institute of Nuclear Medicine and Allied Sciences (INMAS), Lucknow Road, Timarpur, New Delhi-110054
Abstract- An unusual cause of spontaneous hypoglycemia is Insulin Autoimmune Syndrome (IAS) or Hirata Disease, characterized by high levels of insulinemia and circulating autoantibodies to insulin in subjects without prior insulin administration. Till 2009, more than 200 cases from Japan and as many as 60 cases in Caucasians and 20 cases in East Asians have been reported. To the best of our knowledge, this is the second case of IAS reported from India.
Keywords - Hirata Disease, Insulin Autoimmune Syndrome, Autoimmunity, Hypoglycemia, Insulin Autoantibodies
Key Clinical Message - Hirata disease is an autoimmune syndrome rarely seen due to carbimazole/methimazole use in thyrotoxicosis. However, a clinician should keep it in mind when using these drugs and appropriate instructions to the patients should be issued.
Introduction- Insulin Autoimmune Syndrome (IAS) or Hirata Disease (HD), was first described by Hirata in 1970 and is characterized by spontaneous hypoglycemic episodes, a high titre of insulin autoantibodies and increased levels of immune reactive insulin in patients those who are not treated with insulin or oral hypoglycemic agents previously. There is a significant genetic predisposition to IAS as suggested by its association with specific HLA class II alleles, and it is often associated with previous exposure to drugs such as sulfhydryl group in their chemical structures such as Methimazole/ carbimazole. The majority of cases as reported in Japan, IAS is the third leading cause of hypoglycemia (325 patients diagnosed at the end of 2007).1 The syndrome is rare in non-Japanese population: 60 cases in Caucasians and 20 cases in East Asians have been reported till date.2, 3 To best of our knowledge, it is the second case reported in India.