Pitfalls in the diagnosis of insulin autoimmune syndrome (Hirata's disease) in a hypoglycemic child: a case report and review of the literature

A Case of Insulin Autoimmune Syndrome Accompanied With Systemic Joint Pain: A Case Report

Insulin autoimmune syndrome (IAS) is a rare disorder characterised by autoantibodies against endogenous insulin that cause spontaneous hypoglycemic episodes. Here, we present the case of a 66-year-old male with polyarticular pain and dizziness that was initially suspected to be an insulinoma. However, further testing confirmed the presence of IAS. The patient's joint pain fluctuated but improved with the control of blood glucose levels. Although the direct relationship between IAS and joint pain is not well established, individuals with a single autoimmune disorder may develop concurrent autoimmune conditions. Joint pain is prevalent in patients with autoimmune diseases. Although hypoglycemia may cause muscle cramps due to stress responses, direct musculoskeletal damage is uncommon. This case underscores the importance of differential diagnosis, particularly in differentiating between pancreatic cancer and the benign proliferation of pancreatic B cells. Elevated levels of insulin autoantibodies confirm IAS, whereas pancreatic cancer may manifest various symptoms and elevated cancer antigens (CA) 19-9. General physicians should comprehensively investigate hypoglycemia cases, particularly those associated with pancreatic enlargement, and continually monitor for potential malignancies.

Complete laboratory diagnosis of Insulin Autoimmune Syndrome

The definition of Insulin autoimmune syndrome includes the presence of high levels of blood insulin and insulin autoantibodies. We encountered a 45-years-old white man with a high insulin serum value that do not fit with the C-peptide result. To discard or to confirm an analytical interference and diagnose a possible Insulin Autoimmune Syndrome we performed the following investigations: dilution linearity test, heterophilic antibody blocking, polyethylene glycol precipitation, measurements with alternative assays, and gel filtration chromatography by size exclusion. The latter technique confirmed that most of the insulin was complexed with a 150-kDa protein, corresponding to immunoglobulin G, identified as insulin autoantibodies. These antibodies were responsible for hypoglycemia attacks in the patient, who had a previous autoimmune disease. This case highlights the importance of carefully analyzing the results and ruling out possible interferences, as well as considering all kinds of pathologies, even if they are infrequent.

Insulin Autoimmune Syndrome: A Systematic Review

Insulin autoimmune syndrome (IAS) is a rare endocrine disorder characterized by recurrent episodes of severe hypoglycemia, markedly elevated serum insulin, and positive insulin autoantibodies. In recent years, various countries have reported it one after another. It can be seen that we must pay attention to this disease. The diagnosis of IAS is challenging, requiring a careful workup aimed at excluding other causes of hyperinsulinemic hypoglycemia. High levels of insulin autoantibodies are found in patients, and C-peptide is not parallel to insulin, which could be diagnostic. IAS is a self-limiting disease with a good prognosis. Its treatment mainly includes symptomatic supportive treatment, such as adjusting the diet and using acarbose and other drugs to delay the absorption of glucose to prevent hypoglycemia. For patients with severe symptoms, available treatments may include drugs that reduce pancreatic insulin secretion (such as somatostatin and diazoxide), immunosuppressants (glucocorticoids, zaprin, and rituximab), and even plasma exchange to remove autoantibodies from the body. This review provides a comprehensive analysis of the epidemiology, pathogenesis, clinical manifestations, diagnosis and identification, and monitoring and treatment management of IAS.

Nationwide survey of endogenous hyperinsulinemic hypoglycemia in Japan (2017-2018): Congenital hyperinsulinism, insulinoma, non-insulinoma pancreatogenous hypoglycemia syndrome and insulin autoimmune syndrome (Hirata's disease)

AIMS/INTRODUCTION

We aimed to investigate the nationwide incidence, treatment details and outcomes of patients with endogenous hyperinsulinemic hypoglycemia (EHH), including those with transient/persistent congenital hyperinsulinism (CHI), insulinoma, non-insulinoma pancreatogenous hypoglycemia syndrome and insulin autoimmune syndrome (Hirata's disease) in Japan.

MATERIALS AND METHODS

A nationwide, questionnaire-based survey was carried out to determine the number of patients with EHH who were treated for hypoglycemia or hypoglycemia-related complications in 2017-2018. The questionnaires were sent to all hospitals in Japan with >300 beds, and with pediatric and/or adult clinics likely managing EHH patients. The secondary questionnaires were sent to obtain the patients' date of birth, sex, age at onset, treatment details and post-treatment outcomes.

RESULTS

A total of 447 patients with CHI (197 transient CHI, 225 persistent CHI and 25, unknown histology), 205 with insulinoma (118 benign, 18 malignant and 69 unknown subtype), 111 with non-insulinoma pancreatogenous hypoglycemia syndrome (33 post-gastric surgery HH, 57 postprandial HH, 10 nesidioblastosis and 11 unknown subtype) and 22 with insulin autoimmune syndrome were identified. Novel findings included: (i) marked improvement in the prognosis of persistent CHI over the past 10 years; (ii) male dominance in the incidence of transient CHI; (iii) non-insulinoma pancreatogenous hypoglycemia syndrome emerging as the second most common form of EHH in adults; (iv) frequent association of diabetes mellitus with insulin autoimmune syndrome; and (v) frequent post-treatment residual hypoglycemia and impaired quality of life.

CONCLUSIONS

The first nationwide, all age group survey of EHH showed the current status of each type of EHH disorder and the unmet needs of the patients.