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

Graves' disease as a driver of depression: a mechanistic insight

Graves' disease (GD) is characterized by diffuse enlargement and overactivity of the thyroid gland, which may be accompanied by other physical symptoms. Among them, depression can dramatically damage patients' quality of life, yet its prevalence in GD has not received adequate attention. Some studies have established a strong correlation between GD and increased risk of depression, though the data from current study remains limited. The summary of mechanistic insights regarding GD and depression has underpinned possible pathways by which GD contributes to depression. In this review, we first summarized the clinical evidence that supported the increased prevalence of depression by GD. We then concentrated on the mechanistic findings related to the acceleration of depression in the context of GD, as mounting evidence has indicated that GD promotes the development of depression through various mechanisms, including triggering autoimmune responses, inducing hormonal disorders, and influencing the thyroid-gut-microbiome-brain axis. Finally, we briefly presented potential therapeutic approaches to decreasing the risk of depression among patients with GD.

Metformin alleviates the dysregulated testicular steroidogenesis and spermatogenesis induced by carbimazole in levothyroxine-primed rats

Most of the published experiments about carbimazole (CMZ)-induced testicular injury are constructed in normal healthy animals, which lakes the translational identification. Despite metformin (MET) having advantageous effects on injured testicles, its impact on thyroid function is arguable. In the current levothyroxine (LT4)/CMZ model, Wistar rats were primed by LT4 for sixty days. CMZ was then given individually or simultaneously with different doses of MET, 100, 200, and 400 mg, daily for thirty days. Serum was assessed for thyroid profile panel, sex hormones, and gonadotropin levels. Testicular tissues were examined for steroidogenesis, spermatogenesis, inflammation, and apoptosis. Histopathology of thyroid and testes were examined, besides thyroidal nuclear factor (NF)-kB expression. MET in a dose-response manner improved the LT4/CMZ-induced testicular toxicity by increasing the steroidogenic acute regulatory protein (StAR), and 17-β-hydroxysteroid dehydrogenase (17βHSD) activities, the proliferating cell nuclear antigen (PCNA), sperm count and motility, sex hormones, and gonadotropin levels. MET-400 mg markedly decreased the elevated NF-kB expressions, tumour necrosis factor (TNF)-α, caspase-3, and BAX, and increased BCL-2. LT4/CMZ could be used as translational animal modelling. MET displayed a dose-dependent ameliorative effect on the LT4/CMZ model without significant harmful effects on thyroid functions. MET-testicular protective roles in diabetics with thyroidal diseases should be explored.

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.

GLUCOSE CHANGES IN A PATIENT WITH INSULIN AUTOIMMUNE SYNDROME DEMONSTRATED BY CONTINUOUS GLUCOSE MONITORING

Objective

Insulin autoimmune syndrome (IAS) is an unusual cause of hypoglycemia in individuals without underlying diseases. Continuous glucose monitoring (CGM) has rarely been applied for IAS. We present a case of IAS with available 6-day CGM data.

Methods

A 61-year-old Taiwanese man was admitted because of impaired consciousness while driving, caused by a low blood glucose level of 30 mg/dL. He regained consciousness fully after parenteral glucose administration.

Results

During the prolonged fasting test, his C-peptide and insulin levels were respectively 11 ng/mL and 169.34 μIU/mL when plasma glucose was 41 mg/dL. Abdominal magnetic resonance imaging did not show any pancreatic abnormality. His 6-day CGM data revealed fasting hypoglycemia, several instances of postprandial hyperglycemia, and low blood glucose levels before lunch and dinner. Additional diagnostic findings included elevated anti-insulin antibody of 78.2%, thyrotoxicosis due to Graves disease, and gastric ulcer. He was discharged home on prednisolone at 5 mg daily, methimazole at 10 mg daily, and esomeprazole at 40 mg daily. Hypoglycemia and impairment of consciousness did not recur throughout the subsequent year-long follow up.

Conclusion

We proposed a novel approach using CGM coupled with measurements of plasma insulin, C-peptide, and anti-insulin antibodies as the initial investigation for hypoglycemia in non-diabetic subjects. These relatively inexpensive tests may lead to earlier detection of IAS and thus render hospital admission and more costly explorations unnecessary.

Acute pancreatitis, hepatic cholestasis, and erythema nodosum induced by carbimazole treatment for Graves' disease

A 33-year old female was diagnosed as Graves' disease and started on carbimazole. One month later when she was already euthyroid only on carbimazole therapy, she developed acute pancreatitis associated with mild cholestatic hepatitis and erythema nodosum. Carbimazole therapy was interrupted, pancreatic and liver function gradually improved and became normalized two weeks later. Other potential etiological causes of acute pancreatitis, hepatitis and erythema nodosum were excluded. Rechallenge with a single dose of carbimazole led to a new episode of acute pancreatitis and cholestatic hepatitis one day later. The appearance of different hypersensitivity reactions including pancreatitis, hepatitis and erythema nodosum, together with the observation that the interval between drug intake and onset of symptoms became shorter with repeated exposure to carbimazole, point to an immune-mediated mechanism. Carbimazole has to be added to the list of drugs capable of inducing acute pancreatitis, and should be emphasized the need to discontinue this medication as soon as there is evidence of pancreatic dysfunction.

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.

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.