Methimazole and insulin autoimmune syndrome with hypoglycemia

Hirata's disease (insulin autoimmune syndrome) following envenomation by a common krait

Snakebite envenomation is known to cause local as well as systemic haematological, myotoxic and neurological effects. Adverse effects on the endocrine system following envenomation are rarely reported. Hirata's disease, also known as insulin autoimmune syndrome (IAS) is a rare disorder that causes hypoglycaemia due to excessive production of insulin autoantibodies. This report describes a rare case of IAS which developed in a snakebite victim following envenomation by a common krait and antivenom treatment. The patient was initially treated with dextrose and corticosteroids, although plasmapheresis was required to reduce the concentration of insulin antibodies and normalise the patient's glucose level. The patient then made an uneventful recovery without permanent sequelae. This report demonstrates the impacts of envenomation by a common krait on developing Hirata's disease and creates awareness among clinicians who treat snakebite envenomation.

Case report: hypoglycemia secondary to methimazole-induced insulin autoimmune syndrome in young Taiwanese woman with Graves' disease

RATIONALE

Hypoglycemia is an emergent condition with many causes, including underlying diabetes mellitus either with the use of insulin or oral anti-diabetic medications for glucose control, and organ (heart, hepatic, or renal) failure. Insulin autoimmune syndrome (IAS) can also cause hypoglycemia, however it is relatively difficult to diagnose as it is rare clinically. Although uncommon, IAS can be life threatening in patients with persistent hypoglycemia.

PATIENT CONCERN

We report the case of a 27-year-old female with underlying Graves' disease who was treated with methimazole (MTZ). After 6 weeks of treatment, she developed hypoglycemia symptoms accompanied by dizziness and cold sweating. We excluded underlying diabetes mellitus, the use of insulin or oral anti-diabetic medications, and organ failure.

DIAGNOSES

Laboratory data showed elevated insulin and C-peptide levels. Therefore, insulinoma and IAS were suspected. Abdominal computed tomography and magnetic resonance imaging ruled out insulinoma, and MTZ-induced IAS was finally diagnosed.

INTERVENTIONS AND OUTCOMES

The hypoglycemia symptoms resolved after MTZ was switched to propylthiouracil, confirming the diagnosis of IAS.

LESSONS

This case emphasizes the significance of life-threatening MTZ-induced IAS. IAS should be suspected in patients who develop spontaneous hypoglycemia, especially in those with underlying Graves' disease receiving MTZ who present with hyperinsulinism.

Insulin Autoimmune Syndrome (Hirata Disease): A Comprehensive Review Fifty Years After Its First Description

Insulin autoimmune syndrome (IAS), also named Hirata's disease, is a rare condition characterized by hypoglycemic episodes due to the presence of high titers of insulin autoantibodies (IAA). IAS is a form of immune-mediated hypoglycemia, which develops when a triggering factor (ie, a medication or a viral infection) acts on an underlying predisposing genetic background. IAS pathogenesis involves the formation of insulin-IAA complexes that induce glycemic alterations with a double-phase mechanism: IAA prevent insulin to bind its receptor in the postprandial phase, possibly resulting in mild hyperglycemia; thereafter, insulin is released from the complexes irrespective of blood glucose concentrations, thus inducing hypoglycemia. The diagnosis of IAS is challenging, requiring a careful workup aimed at excluding other causes of hyperinsulinemic hypoglycemia. The gold standard for the definitive diagnosis is the finding of IAA in a blood sample. Because IAS is frequently a self-remitting disease, its management mostly consists of supportive measures, such as dietary modifications, aimed at preventing the development of hypoglycemia. Pharmacological therapies may occasionally be necessary for patients presenting with severe manifestations of IAS. Available therapies may include drugs that reduce pancreatic insulin secretion (somatostatin analogues and diazoxide, for instance) and immunosuppressive agents (glucocorticoids, azathioprine and rituximab). The purpose of this review is to provide a comprehensive analysis of the disease, by describing the burden of knowledge that has been obtained in the 50 years following its first description, took in 1970, and by highlighting the points that are still unclear in its pathogenesis and management.

Insulin Autoimmune Syndrome in a 25-Year-Old, Previously Healthy Kuwaiti Man

Insulin autoimmune syndrome (IAS) is a disease characterized by hyperinsulinaemic hypoglycaemia associated with autoantibodies against endogenous insulin. We have described a case of a 25-year-old, previously healthy Kuwaiti man who was admitted to the Mubarak Al-Kabeer hospital with a history of recurrent hypoglycaemia. The patient revealed that he had taken several different injectable anabolic steroids and growth hormone with oral amino acids and other tablets (fat burners) for bodybuilding in the last two months. He denied knowingly using insulin or insulin analogues. The patient had elevated fasting insulin level (>301 uIU/mL) and elevated insulin autoantibodies (>100.0 IU/mL). After appropriate work-up, he was diagnosed with IAS. After treatment with prednisolone (1 mg/kg/day), the patient had complete recovery. In patients with repeated hypoglycaemia, IAS should be considered in the differential diagnosis. Glucocorticoid therapy can be effective for the treatment of hypoglycaemia in patients with IAS.

Insulin autoimmune syndrome possibly caused by coenzyme Q10

A 52-year-old woman was transported for reduced consciousness. Her blood glucose was only 19 mg/dL, but her blood immunoreactive insulin and insulin antibody levels were high at 250 μU/mL and 50 U/mL, respectively. She had no history of insulin treatment, but she had been taking coenzyme Q10 supplements for three months. Her human leukocyte antigen serotype was DR4. After stopping coenzyme Q10, her hypoglycemia disappeared and immunoreactive insulin and insulin antibody levels normalized. Based on the above, she was diagnosed with insulin autoimmune syndrome caused by coenzyme Q10. It is necessary to be aware of the onset of insulin autoimmune syndrome due to coenzyme Q10. Its pathogenesis requires clarification.

Methimazole-induced insulin autoimmune syndrome

BACKGROUND

Hypoglycemia in a critical care setting is often multifactorial with iatrogenic insulin use, sulfonylurea (SU) use, sepsis, adrenal insufficiency and insulinoma among the common causes. Insulin autoimmune syndrome (IAS) is a rare cause of hypoglycemia characterized by the presence of insulin-binding autoantibodies to the sulfhydryl group-containing agents. We report a case of methimazole-induced IAS managed in the intensive care unit.

CASE PRESENTATION

A 76-year-old woman with a history of primary hyperthyroidism was sent from a nursing home for unresponsiveness. Vital signs were significant for hypotension (74/46) and low blood sugars. Fluid resuscitations with normal saline and 50% dextrose stabilized the blood pressure (BP) to 135/75 and her blood glucose to 264. Due to respiratory distress and septic appearance, she required emergency intubation. Nursing home medications were noted for methimazole and absence of any insulin or SU use. Empiric antibiotic treatment was started and fluid resuscitation was continued while home medications were held. Her laboratory values were significant for elevated creatinine, lactic acid, serum cortisol, C-peptide, and insulin. Her cultures, SU screen and computerized tomography (CT) scan were negative for significant findings. On day 2, in addition to 10% dextrose, octreotide was initiated for recurrent hypoglycemia. Her blood glucose (BG) continued to drop throughout the day for which she required glucagon support and a D20 infusion. By day 4, the rate of infusion was titrated up and her BG continued to drop to <60 mg/dl despite D20, octreotide and tube feeds with concentrated calories (1.5 cal/ml). Due to her declining health, her family endorsed palliative care and she was extubated. After day 11, her hypoglycemic episodes resolved and she remained endogenously euglycemic.

CONCLUSIONS

IAS is associated with methimazole use due to formation of autoantibodies to insulin after its interaction with Sulfhydryl (SH) group in methimazole. While IAS is a rare entity, it demands consideration in hypoglycemia in patients with autoimmune conditions.

Two Sisters with Graves' Disease and Similar Clinical Features who Tested Positive for Anti-insulin Antibodies after Thiamazole Treatment

The older of a pair of sisters experienced hypoglycemia after the start of thiamazole (MMI) treatment. Based on a high insulin antibody level, she was diagnosed with insulin autoimmune syndrome (IAS). HLA-DNA typing identified DRB1*04:06. Although a 75-g oral glucose tolerance test (OGTT) showed biphasic insulin secretion, the secretion pattern became monophasic after discontinuation of the MMI. The younger sister was diagnosed with IAS after the start of MMI treatment. HLA-DNA typing identified DRB1*04:06. The 75-g OGTT showed biphasic insulin secretion, but it became monophasic after discontinuation of the MMI. According to the similar insulin secretion kinetics in the two sisters with IAS, we suspect that a genetic predisposition may be associated with the features of anti-insulin antibodies.

Characterization of insulin antibodies by Surface Plasmon Resonance in two clinical cases: brittle diabetes and insulin autoimmune syndrome

In this study, the characterization of insulin (auto)antibodies has been described, mainly in terms of concentration (q), affinity (K_a) and Ig (sub)isotypes by Surface Plasmon Resonance (SPR) in two particular clinical cases of individuals with severe episodes of impaired glycemia. Subject 1 suffers from brittle diabetes associated with circulating insulin antibodies (IA) due to insulin treatment. Subject 2 has insulin autoantibodies (IAA) associated with hypoglycemia in spite of not being diabetic and not having ever received exogenous insulin therapy. After conventional screening for IA/IAA by radioligand binding assay (RBA), we further characterized IA/IAA in sera of both patients in terms of concentration (q), affinity (K_a) and Ig (sub)isotypes by means of SPR technology. In both cases, q values were higher and Ka values were lower than those obtained in type 1 diabetic patients, suggesting that IA/IAA:insulin immunocomplexes could be responsible for the uncontrolled glycemia. Moreover, subject 1 had a predominat IgG₁ response and subject 2 had an IgG₃ response. In conclusion, SPR technology is useful for the complete characterization of IA/IAA which can be used in special cases where the simple positive/negative determination is not enough to achieve a detailed description of the disease fisiopathology.

Two cases of methimazole-induced insulin autoimmune syndrome in graves' disease

We report here the cases of two females with Graves' disease who developed insulin autoimmune syndrome after treatment with methimazole. The patients exhibited a sudden altered mental state after treatment with methimazole for approximately 4 weeks. Patients had hypoglycemia with serum glucose below 70 mg/dL, and laboratory findings showed both high levels of serum insulin and high titers of insulin autoantibodies. The two women had never been exposed to insulin or oral antidiabetic agents, and there was no evidence of insulinoma in imaging studies. After glucose loading, serum glucose, and total insulin levels increased abnormally. One of the patient was found to have HLA-DRB1*0406, which is known to be strongly associated with methimazole-induced insulin autoimmune syndrome. After discontinuation of methimazole, hypoglycemic events disappeared within 1 month. Insulin autoantibody titer and insulin levels decreased within 5 months and there was no further development of hypoglycemic events. We present these cases with a review of the relevant literature.

Insulin autoimmune syndrome induced by methimazole in a Korean girl with Graves' disease

Hypoglycemia was detected in a 15-year-old girl due to loss of consciousness. She was diagnosed with Graves' disease and was being treated with methimazole for the past 4 months. A paradoxically increased insulin levels was found when she suffered from the hypoglycemic episode. An imaging study showed no mass lesion in the pancreas, and insulin antibodies were found in the serum. She was diagnosed with insulin autoimmune syndrome. Her HLA typing was performed, and it revealed HLA-DRB1 (*)04:06. The patient was treated with a corticosteroid for 2 months. After discontinuing the steroid, the insulin antibody titer decreased dramatically, and she did not have any episode of hypoglycemia since. This is the first report of insulin autoimmune syndrome in a Korean girl, and we have revealed the connection between HLA type and insulin autoimmune syndrome in Korea.

Etiopathogenesis of insulin autoimmunity

Autoimmunity against pancreatic islet beta cells is strongly associated with proinsulin, insulin, or both. The insulin autoreactivity is particularly pronounced in children with young age at onset of type 1 diabetes. Possible mechanisms for (pro)insulin autoimmunity may involve beta-cell destruction resulting in proinsulin peptide presentation on HLA-DR-DQ Class II molecules in pancreatic draining lymphnodes. Recent data on proinsulin peptide binding to type 1 diabetes-associated HLA-DQ2 and -DQ8 is reviewed and illustrated by molecular modeling. The importance of the cellular immune reaction involving cytotoxic CD8-positive T cells to kill beta cells through Class I MHC is discussed along with speculations of the possible role of B lymphocytes in presenting the proinsulin autoantigen over and over again through insulin-carrying insulin autoantibodies. In contrast to autoantibodies against other islet autoantigens such as GAD65, IA-2, and ZnT8 transporters, it has not been possible yet to standardize the insulin autoantibody test. As islet autoantibodies predict type 1 diabetes, it is imperative to clarify the mechanisms of insulin autoimmunity.

Distinguishing persistent insulin autoantibodies with differential risk: nonradioactive bivalent proinsulin/insulin autoantibody assay

A subset of children develops persistent insulin autoantibodies (IAA; almost always as the only islet autoantibody) without evidence of progression to diabetes. The aim of the current study was the development and characterization of the performance of a nonradioactive fluid phase IAA assay in relation to standard IAA radioassay. We developed a nonradioactive IAA assay where bivalent IAA cross-link two insulin moieties in a fluid phase. The serum samples positive for anti-islet autoantibodies from 150 newly diagnosed patients with diabetes (Barbara Davis Center plus Diabetes Autoantibody Standardization Program [DASP] workshop) and 70 prediabetic subjects who were followed to diabetes were studied. In addition, sequential samples from 64 nondiabetic subjects who were persistently IAA(+) were analyzed. With 99th percentile of specificity, the new assay with the technology from Meso Scale Discovery Company (MSD-IAA) detects as positive 61% (61 of 100) of new-onset patients and 80% (56 of 70) of prediabetic patients compared with our current fluid phase micro-IAA radioassay (mIAA; 44 and 74%, respectively). In addition, MSD-IAA demonstrated better sensitivity than our mIAA from blinded DASP workshop (68 vs. 56% with the same 99% specificity). Of 64 IAA(+) nondiabetic subjects, 25% (8 of 32) who had only IAA and thus the low risk for progression to diabetes were positive with MSD-IAA assay. In contrast, 100% (32 of 32) high-risk children (IAA plus other islet autoantibodies) were positive with MSD-IAA. The IAA detectable by radioassay, but not MSD-IAA, were usually of lower affinity compared with the IAA of the high-risk children. These data suggest that a subset of IAA with current radioassay (not MSD-IAA) represents biologic false positives in terms of autoimmunity leading to diabetes. We hypothesize that factors related to the mechanism of loss of tolerance leading to diabetes determine high affinity and MSD-IAA reactivity.

Drug-induced insulin autoimmune syndrome

Although insulin autoimmune syndrome (IAS) was found to be strongly related with methimazole, rapidly increasing numbers of cases with alpha lipoic acid-induced IAS have been confirmed to be reported since 2003. As alpha lipoic acid has gained popularity as a supplement for dieting and anti-aging, a warning should be issued.

Insulin Autoimmune Syndrome possibly caused by alpha lipoic acid

Insulin Autoimmune Syndrome (IAS) is a rare disease characterized by hypoglycemia and autoantibodies to insulin without prior insulin administration. Here, we report a case of IAS associated with alpha lipoic acid (ALA). The patient is a 55-year-old man. He began to complain of hypoglycemic symptoms after taking ALA. He lost consciousness in the late postprandial period and blood glucose was found to be 27 mg/dl. A high insulin level and high titers of insulin antibodies were detected. His HLA genotype contains DRB1* 0406. As ALA comes to be used widely, the incidence of IAS due to ALA might increase.

Mature high-affinity immune responses to (pro)insulin anticipate the autoimmune cascade that leads to type 1 diabetes

Children at risk for type 1 diabetes can develop early insulin autoantibodies (IAAs). Many, but not all, of these children subsequently develop multiple islet autoantibodies and diabetes. To determine whether disease progression is reflected by autoantibody maturity, IAA affinity was measured by competitive radiobinding assay in first and subsequent IAA-positive samples from children followed from birth in the BABYDIAB cohort. IAA affinity in first positive samples ranged from less than 10(6) l/mol to more than 10(11) l/mol. High affinity was associated with HLA DRB1*04, young age of IAA appearance, and subsequent progression to multiple islet autoantibodies or type 1 diabetes. IAA affinity in multiple antibody-positive children was on average 100-fold higher than in children who remained single IAA positive or became autoantibody negative. All high-affinity IAAs required conservation of human insulin A chain residues 8-13 and were reactive with proinsulin. In contrast, most lower-affinity IAAs were dependent on COOH-terminal B chain residues and did not bind proinsulin. These data are consistent with the concept that type 1 diabetes is associated with sustained early exposure to (pro)insulin in the context of HLA DR4 and show that high-affinity proinsulin-reactive IAAs identify children with the highest diabetes risk.

Peptide-based molecular analyses of HLA class II-associated susceptibility to autoimmune diseases

Recent advances in knowledge of crystal structures of MHC class II molecules has advanced understanding of the molecular basis for interactions between peptides and HLA class II molecules. Polymorphism of HLA class II molecules influences structures of peptides bound to HLA class II molecules. To better understand mechanisms related to particular HLA class II alleles and autoimmune diseases, it is important to identify self-peptides presented by disease-susceptible HLA class II molecules and triggering disease-causative autoreactive T cells. Autoimmune diseases occur in Caucasians, Blacks and Asians, albeit with a different incidence. In some autoimmune diseases, disease-susceptible HLA class II alleles are closely related but different, and clinical manifestations of diseases differ among ethnic groups. These phenomena strongly suggest that difference in autoimmune self-peptide(s) in the context of disease-susceptible HLA class II molecules may explain the different clinical manifestations of diseases. Therefore, a comparison among disease-susceptible HLA class II alleles, autoimmune self-peptides and clinical manifestations of autoimmune diseases in different ethnic groups would be instructive. We directed efforts to determining: (1) HLA-class II alleles specific to Asian populations and which are associated with susceptibility to autoimmune diseases, (2) binding-peptide motifs for these HLA class II molecules, and (3) self-peptides presented by susceptible HLA class II molecules to stimulate autoreactive T cells related to the development of autoimmune diseases in Asians. In this review, our related recent investigations are described and the uniqueness of HLA class II-associated autoimmune diseases in Asians is given emphasis.

Insulin autoantibodies before and after carbimazole therapy in Asian Indian patients with Graves' disease

Carbimazole therapy can induce insulin autoantibodies (IAA) in Japanese Graves' disease patients, a phenomenon possibly linked to their immunogenetic profile. This phenomenon is not observed in Caucasians. We assessed IAA levels in 114 North Indian Graves' disease patients before and after carbimazole therapy (mean duration 6.2 +/- 3.9 months). The functional significance of IAA was assessed in 46 of them by first phase (sum of +1 and +3 min) insulin response to intravenous glucose (IVGTT) and an oral glucose tolerance test (OGTT) undertaken before commencement of the carbimazole therapy. IAA were measured using a radiobinding assay and expressed as the assay precision unit, S.D. scores (S.D.S), over healthy controls. Before treatment 22 of 114 (19.3%) patients were IAA positive (mean +/- S.D., 5.9 +/- 3.2 S.D.S). After carbimazole therapy a further 11 (9.6%) showed positive for IAA (mean +/- S.D., 3.5 +/- 1 S.D.S). Of the 22 patients who were IAA positive before treatment, 12 became negative after carbimazole therapy. The fasting insulin and first phase insulin responses were similar in IAA positive and IAA negative Graves' disease patients (mean +/- S.D., 61.7 +/- 35.9 versus 88.3 +/- 46.6 pmol/l, P = 0.123 and 1127 +/- 696 versus 1033 +/- 430 pmol/l, P = 0.716, respectively). The OGTT results were comparable in the IAA positive and the IAA negative groups. Thus, North Indian Graves' disease patients, who resemble Caucasians in their HLA haplotypes, behave like Japanese in their tendency to become IAA positive with carbimazole therapy. A subset of the patients who were IAA positive before treatment also demonstrated negative IAA (12/22) after carbimazole therapy.

Imaging of the buffering effect of insulin antibodies in the autoimmune hypoglycemic syndrome

Insulin autoimmune hypoglycemia is characterized by recurrent hypoglycemia and high levels of immunoreactive insulin in the presence of insulin autoantibodies. The mechanisms inducing hypoglycemia are largely unknown. An [123I]insulin scintigraphic scanning was performed to directly demonstrate the effect of antibodies on insulin biodistribution in one patient with this syndrome both before and after treatment. The patient had insulin autoantibodies IgG3 lambda, which had a single site dissociation constant (Kd = 10(-7) mol/L, by Scatchard analysis), a very fast dissociation rate of immune complexes, and a very rapid association of [125I]insulin. Insulin receptors on red blood cells were down-regulated. The [123I]insulin scintigraphic study imaged the buffering effect of antibodies on insulin bioavailability. [123I]Insulin was not removed from the blood, and no liver or kidney uptake of the hormone occurred. The frequency and severity of hypoglycemic episodes required treatment. Insulin antibody levels decreased and [123I]insulin biodistribution improved after treatment with plasmapheresis and prednisone. Improved hormone bioavailability was further evidenced by the reduction in the hypoglycemic delay after i.v. insulin from 90 min before any treatment to 60 min after plasmapheresis and 30 min after steroid administration. Glucose tolerance was normal after treatment. Plasmapheresis followed by steroid treatment can lower the insulin antibody concentration, abolish severe hypoglycemia, and improve insulin biodistribution and glucose tolerance in insulin autoimmune hypoglycemia.

Insulin antibodies and hypoglycemia in diabetic patients. Can a quantitative analysis of antibody binding predict the risk of hypoglycemia?

We report a noninsulin-dependent diabetes mellitus (NIDDM) patient with spontaneous, severe hypoglycemic reactions and the presence of insulin antibodies. He had a remote antecedent history of beef-pork insulin therapy as well as exposure to hydralazine. Detailed insulin binding kinetic studies were performed in this patient as well as in six other insulin-treated diabetic patients with anti-insulin antibodies (three with and three without an obvious cause of hypoglycemia). Sera from the current patient and five of the six other diabetic patients (one NIDDM, four IDDM) revealed two types of binding sites: high-affinity with low capacity (Kd, 0.4-12.4 x 10(-9) mol/L; binding capacity, 0.6-659 mU/L) and low-affinity with high capacity (Kd, 0.3 to 35.7 x 10(-7) mol/L; binding capacity; 202-113,680 mU/L). One NIDDM patient had only high-affinity antibodies (Kd, 22.9 x 10(-9) mol/L; binding capacity of 78 mU/L). Type of diabetes mellitus, insulin antibody titers or their binding capacities, insulin levels (total, bound, or free), and bioavailable insulin were not related to hypoglycemic reactions. Two calculated values by the method described tended to discriminate patients with and without hypoglycemia. The calculated amount of low-affinity antibody bound insulin ranged from 69.4-2090 mU/L vs < 4-70.6 mU/L in patients with and without hypoglycemia, respectively. The best discrimination was afford by the percent saturation of low-affinity binding sites; values were clearly higher in the patients with hypoglycemia (2.5-34.4%) than in those without hypoglycemia (not detectable, 0.06, 0.15%). Consideration of the possible drug-associated insulin antibody formation in insulin-treated diabetics and the novel quantitative analysis of the antibody binding kinetics should prove helpful in evaluating patients with high insulin antibody titers and assessing the risk of hypoglycemia.

Insulin autoimmune syndrome as a cause of spontaneous hypoglycemia in alcoholic cirrhosis

Hypoglycemia in fulminant hepatic failure and hyperinsulinemia in cirrhosis are well-described phenomena. A patient with alcoholic cirrhosis who developed fasting hypoglycemia with an extremely high immunoreactive insulin level and a mildly elevated C-peptide level is reported. An insulinoma was excluded by detailed radiological imaging of the pancreas and by endoscopic ultrasonography. Detection of very high levels of insulin autoantibodies with no prior exposure to exogenous insulin confirmed the diagnosis of insulin autoimmune syndrome. During his hospital course, the patient developed another rare syndrome, acquired inhibitors to factor V, which led to the fatal coagulopathy that resulted in his death. Insulin autoimmune syndrome is the third leading cause of spontaneous hypoglycemia in Japan, where it has been associated with a variety of diseases and drugs. Outside of Japan, only approximately 20 cases have been reported and usually have been found in the context of an underlying autoimmune disorder or prior exposure to sulfhydryl drugs. It is believed that this is the first case reported outside Japan occurring in association with alcoholic liver disease, and the first in the world with coexisting acquired inhibitors to factor V.

Insulin autoimmune syndrome in Japan

Since 1970, 197 patients with insulin autoimmune syndrome (IAS) showing severe spontaneous hypoglycemia have been reported in Japan. This is characterized by a high titer of anti-insulin autoantibodies without evidence of exogenous insulin administration. IAS is the third leading cause of spontaneous hypoglycemia in Japan, while only 21 cases have been reported in Europe and the United States. High levels of the extractable native human insulin and of the characteristic insulin autoantibodies in the sera of the IAS patients have been proved. Recently a significant association of HLA-DRB1*0406/DQA1*0301/DQB1*0302 with this syndrome has been found in the IAS patients in Japan.

Insulin autoimmune syndrome (Hirata disease): clinical features and epidemiology in Japan

Since Hirata et al. first reported a patient with insulin autoimmune syndrome in 1970, 197 cases have been reported in Japan as of December, 1992. The clinical profiles of these 197 cases were as follows; the peak age at onset was 60-69 years and peak duration of hypoglycemic attacks was more than 1 and less than 3 months. There was no gender difference in the peak age of onset or duration of hypoglycemic attacks. Approximately 82% of the IAS patients had spontaneous remission without any positive treatment. Before diagnosis of IAS, 43% of the patients with IAS had been taking medication; methimazole (MTZ) for Graves' disease, alpha-mercaptopropionyl glycine (MPG) for cataracts, liver disease or rheumatoid arthritis, or glutathione for liver disease, all of which are sulfhydryl compounds. After such sulfhydryl compounds were discontinued, the hypoglycemic attacks subsided. Three patients with IAS experienced recurrence of the hypoglycemic attacks after re-administration of MTZ and MPG, although 6 patients who developed IAS without exposure to any drug had recurrent attacks without exposure to any drug around 1 year after the first hypoglycemic attacks had stopped. Thus, hypoglycemia in IAS is mainly transient and the development of IAS may be related to sulfhydryl compounds.

Longitudinal changes of serum insulin concentration and insulin antibody features in persistent insulin autoimmune syndrome (Hirata's disease)

In a 56-year-old woman with granulomas of gold thioglucose in her hips, who developed insulin autoimmune syndrome, the relationships among the frequency or severity of hypoglycemic attacks, serum insulin (IRI) concentration, and characteristics of insulin antibodies were investigated during the clinical course with steroid treatment and two resection operations for the gold-thioglucose granulomas. When hypoglycemia was severe, the total IRI level was elevated, and Scatchard analysis showed that a high-affinity (k1), low-capacity (b1) population of antibodies had a relatively low affinity constant and very high binding capacity compared with the same population of antibodies in insulin-treated diabetic patients. When the attacks were relieved by steroid treatment and/or granuloma resection operation, the total IRI level was decreased and the high-affinity (k1), low-capacity (b1) population of antibodies showed a higher affinity constant and a lower binding capacity than those during the attacks. This indicated that the antibodies changed their characteristics to release insulin into the serum. The k1/b1 population of insulin antibodies with the lower affinity constant and higher binding capacity may easily release human insulin into the serum, leading to hypoglycemia. The longitudinal change of the k1/b1 population suggests a clonal change of the B cells producing the insulin antibody in insulin autoimmune syndrome.

Low titer, competitive insulin autoantibodies are spontaneously produced in autoimmune diseases of the thyroid

The occurrence of multiple endocrine autoimmunity with organ-specific autoantibodies is well known. In this study we evaluated the presence of competitive insulin autoantibodies (IAA) in immune and non-immune diseases of the thyroid, utilizing a sensitive and specific radiobinding assay. We studied 37 patients with Graves' disease, 44 patients with Hashimoto's thyroiditis, 11 patients with non-immune thyroid diseases and 30 normal controls. In 5/37 (13.5%), 7/44 (15.9%) patients with Graves' and Hashimoto's diseases, respectively, but in none of those with non-immune thyroid disease or of the controls, IAA levels exceeded our upper limit of normal range (50 nunits/ml) (P < 0.01). Positive IAA levels ranged between 50 and 123 nunits/ml with fluctuation of these levels over time. Islet cell antibodies were not detected in any of the patients and the controls in the study. No association was found between propylthiouracile treatment and level of IAA. In none of 10 IAA-positive patients was the early phase insulin secretion of the intravenous glucose tolerance test below 46 mu units/ml, and in 2 subjects repeated tests after 3 years showed conserved insulin secretion. In conclusion, our findings show that 15% of patients with autoimmune thyroid diseases, produce specific IAA which do not seem to reflect aggressive beta cell destruction.

Prospective evaluation of beta-cell function in insulin autoantibody-positive relatives of insulin-dependent diabetic patients

During the preclinical period of insulin-dependent diabetes mellitus (IDDM), progression to clinical IDDM is characterized by declining beta-cell function. Although the presence of insulin autoantibodies (IAA) improves the ability of islet cell antibodies (ICA) to predict subsequent clinical IDDM, few studies have examined the risk of developing IDDM in subjects positive for IAA but negative for both ICA and antibodies to glutamic acid decarboxylase (64kA). To investigate this question, detailed beta-cell function tests (acute insulin response to glucose [AIRgluc] and slope of glucose potentiation) were performed on eight IAA-positive first-degree relatives of insulin-dependent diabetics. All eight subjects were negative for ICA, and seven were tested for 64kA and were negative. Five subjects were studied prospectively for 22.4 +/- 9.4 months, while three subjects had only initial studies. Initial beta-cell function tests were normal in each subject. AIRgluc was 122.2% +/- 19.0% of the expected normal response, while slope was 168.6% +/- 20.6% of expected normal response. beta-cell function remained normal and remarkably stable in the five subjects followed prospectively. AIRgluc did not significantly change from an initial value of 147.9% +/- 23.1% of expected to 153.2% +/- 22.4% (NS). The slope of glucose potentiation varied little from 165.5% +/- 39.4% initially to 159.5% +/- 27.3% (NS) at the most recent determination. We conclude that among nondiabetic first-degree relatives of IDDM subjects, the presence of IAA in the absence of ICA and 64kA is not usually associated with and therefore does not reliably predict beta-cell dysfunction or progressive deterioration in beta-cell function.

Increased specificity and sensitivity of insulin antibody measurements in autoimmune thyroid disease and type I diabetes

Insulin autoantibodies (IAA), a marker for insulin-dependent diabetes mellitus (IDDM), have been reported in other diseases such as thyroid disease and after treatment with sulfhydryl containing medications. Reported prevalences of IAA in non-diabetics vary widely, probably due in part to methodological differences between laboratories. In addition, certain sera may have a high non-specific binding to insulin. We compared a radioimmunoassay (RIA) for IAA which included non-specific binding with an RIA that incorporated a competitive displacement with cold insulin to remove non-specific binding. Using the RIA which measured specific plus non-specific binding, IAA positivity was found in 22/92 (23.9%) of sera from thyroid disease patients, 16/124 (12.9%) of random masked sera from a hospital laboratory, 27/335 (8.1%) of first degree relatives of IDDM patients, 63/178 (35.4%) of subjects with newly diagnosed IDDM, and 0/92 (0%) of normal controls. Insulin antibodies (IA) were found in 80/99 (80.8%) of insulin-treated diabetic subjects. In contrast, using the displacement assay which allowed measurement of specific binding, the frequency of IAA positivity was lower for subjects with thyroid disease (7/92 (7.6%)), random hospital sera (12/124 (9.8%)), and for first degree relatives of IDDM patients (8/335 (2.4%)), while higher for subjects with newly diagnosed IDDM (71/178 (39.9%)). Subjects with insulin-treated diabetes (78/99 (78.8%)) and normal subjects (1/92 (1.1%)) showed little change. Strikingly, three of the eight (37.5%) relatives of IDDM patients that were positive in the RIA measuring specific binding were detected only because cold displacement was utilized. We conclude: (1) subjects with thyroid disease and first degree relatives of IDDM patients frequently have high non-specific binding for IAA in an RIA not employing a cold displacement step, (2) in some newly diagnosed IDDM patients and first degree relatives of IDDM patients, IAA may be missed by an assay not optimized to measure specific binding, and (3) displacement with cold insulin increases both the specificity and sensitivity of RIAs measuring insulin autoantibodies.

Reactive hypoglycemic coma due to insulin autoimmune syndrome: case report and literature review

Recurrent episodes of postprandial hypoglycemic symptoms culminated in hypoglycemic coma in a hypertensive but otherwise healthy man while he was taking hydralazine. The patient was found to have an extreme elevation in the immunoreactive insulin level, leading to the discovery of insulin antibodies in the absence of prior exposure to exogenous insulin. Negative results of an anatomic study of the pancreas and an inability to reproduce hypoglycemia during a prolonged fast helped to exclude insulinoma. In contrast, symptomatic hypoglycemia developed in response to oral glucose loading and was associated with an elevation in total and free insulin as well as C-peptide levels. The patient was diagnosed with insulin autoimmune syndrome, which, although a common source of hypoglycemia in Japan, has been well documented in only 15 cases from other countries. HLA typing revealed the patient to be positive for groups Cw4 and DR4, a combination that has been preliminarily associated with insulin autoimmune syndrome in Japan. Unlike the majority of cases previously reported, this patient had no clinical or serologic evidence of an underlying autoimmune disorder and had not been exposed to drugs containing sulfhydryl groups. This case adds to the world literature on insulin autoimmune syndrome, lends support to a postulated HLA association, and documents the presence of insulin autoantibodies in the absence of another underlying autoimmune disorder.

Strong association of insulin autoimmune syndrome with HLA-DR4

Insulin autoimmune syndrome is characterised by spontaneous hypoglycaemia without evidence of exogenous insulin administration, a high serum concentration of total immunoreactive insulin, and the presence of insulin autoantibodies in high titre. HLA typing of 27 patients with insulin autoimmune syndrome showed that all had DR4, which was present in only 43% of 51 healthy controls (odds ratio 72.1, p less than 2 x 10(-6), and 19 (70%) of the patients were positive for the allelic combination, Cw4, Bw62, and DR4. Analysis of the nucleotide sequences of the DRB1, DQA1, and DQB1 genes showed that all the patients had DRB1*0406, DQA1*0301, and DQB1*0302, compared with only 14% of the controls (odds ratio 281, p less than 1 x 10(-10). We conclude that the development of insulin autoimmune syndrome is associated with a strong genetic predisposition.

Human insulin-specific immunoglobulin G antibody and hypoglycemic attacks after the injection of gold thioglucose

A 56-year-old woman with granulomas of gold thioglucose in her hips exhibited recurrent bouts of hypoglycemic attacks. The first attack occurred 2 years after the last injection of gold thioglucose, when large amounts of extractable insulin and human insulin-specific antibody were noted in her serum. Histological examination of the resected granulomas showed marked infiltration of lymphocytes, plasma cells, and macrophages containing yellowish-brown granules, which proved to be gold by electron microscopy using X-ray microanalysis. After resection of the granuloma, however, the frequency of the hypoglycemic attacks decreased remarkably as well as the levels of both extractable insulin and human insulin-specific antibody.

An unusual case of recurrent hypoglycaemia: 10-year follow up of a child with insulin auto-immunity

We report the case of a child with hypoglycaemia due to insulin auto-immunity. Insulin auto-immunity is the third most frequent cause of hypoglycaemia in Japan where the first cases were described. The child has been followed for the past 10 years with recurrence of hypoglycaemic symptoms and high titres of insulin antibodies.

Polymorphism of insulin antibodies in six patients with insulin-immune hypoglycaemic syndrome

Insulin antibodies in six patients with immune hypoglycaemic syndrome were studied. The antibodies displayed a higher affinity for bovine insulin in two patients, were specific for human insulin in one patient and non-species specific in the other three patients. The predominant IgG subclass of the insulin antibodies was IgG4 in two patients, IgG3 in two and IgG1 in two. In one of these, the other three subclasses were also detectable. Insulin autoantibodies of four patients were homogeneous with regard to light chains (kappa), and those of the other two contained both kappa and gamma light chains. Analysis of insulin immune complex size by fast protein liquid chromatography was possible in three patients and demonstrated immune complexes with elution profile close to that of IgG, although not exactly superimposable to the one obtained with a mouse monoclonal insulin antibody. In two patients, avidity was too low to permit chromatography of the immune complexes, and, moreover, in these two cases insulin antibodies were of the IgG3 isotype and spontaneously formed aggregates independently of insulin binding. We conclude that insulin antibodies of the insulin immune syndrome are polymorphic but different from those generated by insulin therapy.

Hyperthyroidism in children and adolescents

Hyperthyroidism in infants and children usually is caused by Graves' disease; however, several other diseases can also produce hyperthyroidism in these age groups. Because the pathophysiology and clinical course of these conditions differ, optimal treatment depends on precise diagnosis.

Insulin autoantibodies in Graves' disease--before and after carbimazole therapy

Insulin autoantibodies (IAA) are well documented in patients with insulin-dependent diabetes (IDDM) prior to the administration of insulin and in patients with reactive hypoglycaemia--the insulin autoimmune syndrome (IAS). It has been suggested that IAA can be induced by the administration of drugs containing sulphydryl groups, such as carbimazole, and they have been frequently described in Graves' disease. An alternative explanation is the clustering of autoantibodies in autoimmune disease. We studied 39 patients (37 females, two males, age range 14 to 61 years; mean 33.8 years) with proven Graves' disease and no previous treatment with carbimazole. Fifteen of the 39 patients had a family history of other autoimmune diseases. IAA and thyroid autoantibodies were assayed at diagnosis and monthly thereafter while on treatment with carbimazole, for up to 6 months. IAA were measured using a direct-binding solid-phase ELISA and specificity was confirmed by absorption studies using insulin covalently coupled to Sepharose beads. At diagnosis 33 of the 39 patients (85%) were positive for thyroid microsomal antibodies, 13 (33%) were positive for thyroglobulin antibodies, and 4 (10%) were positive for IAA. All IAA-positive patients had microsomal antibodies at diagnosis, and two had thyroglobulin antibodies in addition. After 4 months on carbimazole, the frequency of thyroid microsomal autoantibodies was unchanged (83%), while that of anti-thyroglobulin antibodies had fallen (8.6%). All four IAA-positive patients remained positive, and studies of binding to human, porcine and bovine insulin demonstrated that one serum, initially human insulin specific, later became cross-reactive with all three. We conclude that low titres of IAA are found in Graves' disease, and are associated with the presence of autoimmunity rather than the carbimazole. Symptomatic hypoglycaemia, however, is rare in Caucasian patients.

Autoimmune insulin syndrome

Initially described in Japan, the autoimmune insulin syndrome is caused by the presence of anti-insulin antibodies in patients who have never received insulin. This syndrome accounts for spontaneous or reactive hypoglycaemia with very high levels of total immuno-reactive insulin. Discordance between the levels of immunoreactive insulin and C peptide indicate the possible presence of anti-insulin antibodies; this can avoid an incorrect diagnosis of insulinoma. These autoimmune hypoglycaemias often present a difficult diagnostic problem in distinguishing them from factitious hypoglycaemia. The course of the autoimmune insulin syndrome is usually favourable, with a spontaneous rapid diminution of the levels of anti-insulin antibodies. The reasons for the appearance of anti-insulin antibodies and the exact mechanisms of the hypoglycaemia remain uncertain. However, the frequent association of the autoimmune insulin syndrome with certain autoimmune diseases suggest a common immune dysfunction. Drugs containing a sulphydryl group have been implicated in the aetiology of this syndrome.

Autoantibodies to the insulin receptor as a cause of autoimmune hypoglycemia in systemic lupus erythematosus

A 52-year-old black woman presented with clinical features of systemic lupus erythematosus (SLE) and severe fasting hypoglycemia. Hypoglycemia was secondary to autoantibodies to the insulin receptor that were detected in the patient's serum. There were no anti-insulin antibodies, and other causes of hypoglycemia were excluded. Treatment with high-dose glucocorticoids resulted in restoration of euglycemia associated with resolution of circulating anti-receptor antibodies and parallel improvement in clinical and laboratory features of SLE. This case is compared with other cases of autoimmune hypoglycemia due to anti-receptor antibodies.

Spontaneous hypoglycemia and insulin autoantibodies in a patient with Graves' disease

A 31-year-old woman with Graves' disease developed fasting hypoglycemia after treatment for 3 weeks with methimazole. Although the patient had not received exogenous insulin, high titers of insulin autoantibodies were found in serum and large amounts of total and free insulin (1550 and 82 microU/ml, respectively) and C-peptide reactivity (CPR, 22 ng/ml) were detected in serum. After glucose loading, blood glucose and total insulin levels increased abnormally. The immunoglobulin class of the autoantibodies was IgG and the light chains were of the kappa type. The titers of insulin autoantibodies, elevated serum total and free insulin, and CPR levels decreased gradually, but insulin autoantibodies and elevated insulin levels were still present in the serum 8 months after the episode of hypoglycemia. These findings suggest that the patient's fasting hypoglycemia was due to excess free insulin released from antibody-bound insulin, and that methimazole might play a role in the initiation of production of insulin autoantibodies.

Insulin autoimmune syndrome with insulin-resistant diabetes at the incipient stage prior to hypoglycemic attacks

Insulin autoimmune syndrome is characterized by spontaneous hypoglycemia, glucose intolerance, hyperinsulinemia and insulin-binding antibodies in serum without previous immunization. A 31-year-old man with Graves' disease developed insulin autoantibodies after therapy with methimazole. The patient was unique in that persistent hyperglycemia with polyuria and polydipsia had continued for several days before frequent hypoglycemic attacks appeared. We were able to extract a huge amount of immunoreactive insulin (116,000 microU/ml) with acid-ethanol from his serum obtained in the diabetic stage, and serum C-peptide immunoreactivity was as high as 268 ng/ml. The insulin-binding activity of his serum was quite potent, and when 1:5,000 diluted serum was incubated with 125I-porcine insulin, 71.2% of the label could be precipitated by polyethylene glycol. The insulin-binding protein was identified as mainly IgG with kappa light chains. Insulin-binding activity was not detected in serum obtained before methimazole therapy, suggesting that the drug was responsible for the induction of antibodies in this patient. The antibodies recognized porcine, sheep, bovine and horse insulins as well as human insulin. The mechanisms by which the antibodies produced hyper- and hypoglycemia have also been discussed.

Organ-specific autoimmunity: a 1986 overview

The normally functioning immune system is subject to intricate networks of regulatory mechanisms: it is therefore not surprising to find that autoimmune diseases present a complex pathogenic picture in which the relative contributions of various factors probably determine the precise nature and course of disease. This is particularly evident in the effector mechanisms of organ-specific autoimmunity which are described in this chapter. These ultimately give rise to the disease symptoms, and can be directly cytotoxic, or may either stimulate or block functional activity or growth of the target cells. Their various contributions to human diseases are becoming more firmly established, as in Type I diabetes, or are only now being described, as in the case of EC-Ab in protracted diarrhea of infancy and as evidenced by the growing lists of receptor-stimulating or -blocking antibodies. The nature and precise location of relevant autoantigens is also coming under closer scrutiny. The answers to the question of why these diseases arise in the first place remain more elusive. However, it is again likely that a variety of factors can contribute. The attractive possibility of a role for idiotypic interactions is gaining ground, particularly within the context of antibodies to hormones and their receptors. Another potential mechanism which we believe may be of central importance, particularly in the development of organ-specific destructive autoimmunity, and which we have discussed here in detail, is the aberrant expression of HLA Class II molecules by target cells. Whether this is actually an initiating factor is presently not known, but its potential for promoting pathogenesis both early and late in the process is clear. Furthermore, the complex nature of the regulation of epithelial Class II expression may help to explain the heterogeneity of features and course of disease in different patients with the same underlying pathology. All these advances in our basic understanding of the disease processes should ultimately lead to more effective and specific means of therapeutic intervention.

Clinical and biochemical aspects of the insulin autoimmune syndrome (IAIS)

A 44-year old patient presented with recurrent hypoglycemic attacks after ingestion of carbohydrates. High insulin levels in the range of 350 microU/ml (normal range less than 20 microU/ml) were detected which rose to peak levels of 2,460 microU/ml (normal range less than 300 microU/ml) after oral glucose. The apparently high insulin concentrations were caused by insulin autoantibodies interfering in the radioimmunoassay (RIA) system (and thus with correct insulin quantitation). 125I-insulin added to the patient's serum was not bound to dextran-coated charcoal but was precipitated with antihuman IgG serum. The antibodies bound human, porcine, and bovine insulin with similar affinity. Following Sephadex G-50 gel filtration, the patient's insulin eluted after the void volume. Free insulin was extracted from serum using Sep-Pak C 18 cartridges and characterized by high pressure liquid chromatography (HPLC); it eluted similarly to synthetic human insulin. Quantitation of free insulin during a hypoglycemic attack (3.5 h after oral glucose, with a blood sugar of 20 mg/dl) showed an increased insulin level of 50 microU/ml. Insulin receptor concentration on erythrocytes was near the lower normal limit. We believe that the insulin antibodies present in this patient's serum (who supposedly never received insulin) led to the formation of a large circulating insulin pool, binding the insulin released after glucose stimulation, and causing hypoglycemias by delayed postprandial liberation of bound insulin.

Antithyroid drugs

Over the past four decades, a great deal has been learned about the pharmacology and mechanisms of action of antithyroid drugs. Their ability to inhibit hormone biosynthesis involves complex interactions with thyroid peroxidase and thyroglobulin, many of which are still poorly understood. Their spectrum of activity is much wider than previously thought, and a number of clinically important extrathyroidal actions have been identified. Despite a greater appreciation for the intricacies of antithyroid-drug pharmacology, controversies still surround the use of these agents in the treatment of thyrotoxicosis. These controversies are apt to continue until the pathophysiology of Graves' disease is fully elucidated.