title: High fasting serum insulin level due to autoantibody interference in insulin immunoassay discloses autoimmune insulin syndrome: a case report.
abstract: Insulin-antibodies are a cause of misleading results in insulin immunoassays. They may also mediate deleterious blood glucose variations. A patient presented with overtiredness, recurrent episodes of sweating, dizziness and fainting fits. A fasting serum insulin assay performed on a Modular platform (Modular analytic E170, Roche Diagnostic, Meylan, France) showed a highly elevated value of 194.7 mIU/L, whereas on the same sample glucose and C-peptide levels were normal. Other immunometric insulin assays were performed, as well as antibodies anti-insulin radiobinding assay (RBA) and gel filtration chromatography (GFC). While complementary insulin assays yielded closer to normal fasting levels, the free insulin concentration assessed after PEG precipitation was 14.0 mIU/L and the RBA was positive. GFC revealed that most of the insulin was complexed with a 150 kDa molecule, corresponding to an immunoglobulin G (IgG). A high fasting serum insulin level in a patient with neuroglucopenic symptoms was related to a high insulin-antibody level, suggesting an insulin autoimmune syndrome.
authors: Institut médical d'analyse génomique, Labosud-Ocbiologie, Montpellier, France, Département de biologie, Institut du cancer, Montpellier, France.
authors: Pierre-Jean
authors: PJ
authors: Lamy
authors: BIOMNIS, Lyon, France.
authors: Corinne
authors: C
authors: Sault
authors: Département d'endocrinologie, diabète, nutrition, CHU de Montpellier, et Institut de Génomique Fonctionnelle, UMR CNRS 5203/Inserm U1191, Université de Montpellier, Montpellier, France.
authors: Eric
authors: E
authors: Renard
mesh_terms: D001327:Autoimmune Diseases / Q000097:blood*; D002850:Chromatography, Gel; D003920:Diabetes Mellitus / Q000097:blood / Q000175:diagnosis; D005188:False Negative Reactions; D005215:Fasting / Q000097:blood; D005260:Female; D005602:France; D006801:Humans; D007118:Immunoassay / Q000379:methods / Q000592:standards; D007328:Insulin / Q000032:analysis* / Q000097:blood* / Q000276:immunology; D007330:Insulin Antibodies / Q000009:adverse effects* / Q000097:blood; D008875:Middle Aged; D013577:Syndrome
chemical_list: D007328:Insulin; D007330:Insulin Antibodies
keywords: autoimmunity; insulin antibody; insulin auto-immune syndrome; insulin immunoassay; interference