SFENCC2020 Society for Endocrinology National Clinical Cases 2020 Poster Presentations (72 abstracts)
Two contrasting cases of spontaneous severe hypoglycaemia secondary to anti-insulin antibodies (Insulin Autoimmune Syndrome / Hirata disease)
Randa Eltayeb 1 , Zeenat Banu 1 , Umaira Aziz 1 , Hiba Eldigair 1 , Judith Kisalu 1 , Emma Woolman 1 , Huw Beynon 1 , David Church 2 , Robert Kenneth 2 , Bernard Khoo 1 , Mark Cohen 1 & Efthimia Karra 1
1Royal Free Hospital, London, UK; 2University of Cambridge, Cambridge, UK
Insulin Autoimmune Syndrome (IAS)/Hirata disease is a very rare condition in which anti-insulin antibodies result in accumulation of high circulating concentrations of insulin in complexes. Hypoglycaemia in IAS occurs when insulin is released from the antibodies during fasting. We present two contrasting cases of Hirata disease. Both patients presented with symptomatic hypoglycaemia. Patient-A is a 52-year old obese Thai female, with acanthosis nigricans and a strong family history of T2DM. Patient-B is a 28 year-old normal-BMI Caucasian female. None of the patients received any regular medication or had history of autoimmunity. Whipple’s triad was confirmed at 10 h supervised fast for patient-A. Nadir laboratory glucose was 1.8 mmol/l, coupled with hyperinsulinaemia and a high insulin-to-C-peptide ratio (insulin=9809 mIU, C-peptide=3690 pmol/l, insulin:C-peptide=18.5). Patient-B has ongoing issues with recurrent hypoglycaemia due to chronic persistence of high capacity insulin autoantibodies, developed hypoglycaemia at 4 h during a supervised fast, with hyperinsulinaemia and a high insulin-to-C-peptide ratio (plasma glucose=2.2 mmol/l, insulin=17 800 pmol/l, C-peptide=409 pmol/l, insulin:C-peptide-ratio=43.5). Hook-effect phenomena were excluded in both cases. Insulin was lower post-PEG precipitation, indicating that much of the measured insulin was complexed in macromolecular aggregates. Sulphonylurea screen was negative, imaging unremarkable, ANA and anti-dsDNA antibodies negative. Anti-insulin-receptor Abs were negative, whereas anti-insulin IgG antibodies were positive. Chromatography demonstrated insulin sequestration by anti-insulin antibodies, identifying monomeric and antibody-bound insulin. Pending diagnosis, a trial of diazoxide was ineffective in both cases. In light of positivity of anti-insulin IgG antibodies, prednisolone and mycophenolate mofetil (MMF) treatment were initiated in patient-A, and later euglycaemia maintained on MMF monotherapy. In patient-B dexamethasone and adjuvant MMF induced only partial response. Subsequent Rituximab-induced CD20 depletion and adjuvant steroid treatment strategy was adopted with partial efficacy. Patient-B later underwent plasmapheresis with adjuvant Rituximab therapy. We discuss the diagnostic challenges in IAS, the diverse phenotype and treatment responses in our two cases.
Volume 69
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Endocrine Abstracts
ISSN 1470-3947 (print) | ISSN 1479-6848 (online)
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