Hypoglycemia due to an insulin binding antibody in a patient with an IgA-kappa myeloma.

• Abstract: CONTEXT: Autoantibodies to insulin have been described to cause spontaneous hypoglycemia in nondiabetic subjects. There have been occasional reports of spontaneous hypoglycemia due to monoclonal anti-insulin antibodies. We present the first report of a patient with an IgA-kappa myeloma in whom frequent hypoglycemia resulted from the ability of the monoclonal IgA-kappa to bind insulin. OBJECTIVES: The aim of this study was to describe the occurrence of profound hypoglycemia in a patient with IgA-kappa myeloma, characterize biochemically the nature of the IgA:insulin complex present, and place this case in the context of the published literature on hypoglycemia resulting from autoantibodies to insulin. DESIGN: A case study was performed. PATIENTS: A single case of profound hypoglycemia associated with IgA-kappa myeloma was studied. INTERVENTION: There were no interventions. MAIN OUTCOME MEASURES: A case study was performed. RESULTS: Polyethylene glycol precipitation and gel filtration chromatography were used to demonstrate high-molecular weight insulin immunoreactivity in the patient's plasma. This was characterized as an insulin binding IgA-kappa paraprotein present at 4200 mg/dl (42 g/liter) with a relatively high insulin dissociation constant of 0.32 microm/liter using radiolabelled insulin binding studies. CONCLUSIONS: We present the first case of hypoglycemia due to IgA binding insulin antibodies in a patient with an IgA-kappa paraprotein myeloma. The hypoglycemia was associated with high-plasma insulin levels and relatively low C-peptide levels. A plausible mechanism for the hypoglycemia is the delayed clearance of insulin. This case broadens the spectrum of monoclonal gammopathies that have been associated with anti-insulin reactivity and spontaneous hypoglycemia.
• Authors: D J Halsall, M Mangi, M Soos, M N Fahie-Wilson, G Wark, R Mainwaring-Burton, S O'Rahilly (Affiliation: Department of Clinical Biochemistry, Addenbrooke's Hospital, Cambridge, UK. djh44 at hermes.cam.ac.uk)
• Journal: The Journal of clinical endocrinology and metabolism (J Clin Endocrinol Metab) Vol. 92 Issue 6 Pg. 2013-6 (Jun 2007) ISSN: 0021-972X [Print] United States
• PMID: 17405845 (Publication Type: Case Reports, Journal Article)

Chemical References

• Autoantibodies
• Immunoglobulin A
• Immunoglobulin kappa-Chains
• Insulin

Topics

• Aged
• Antibody Specificity
• Autoantibodies (blood, immunology)
• Chromatography, Gel
• Humans
• Hypoglycemia (etiology, immunology)
• Immunoglobulin A (blood, immunology)
• Immunoglobulin kappa-Chains (blood, immunology)
• Insulin (blood, immunology)
• Male
• Multiple Myeloma (complications, immunology)