TY - JOUR
T1 - Pseudoinsulinoma in a white man with autoimmune hypoglycemia due to anti-insulin antibodies
T2 - value of the free C-Peptide assay
AU - Arzamendi, Audrey E.
AU - Rajamani, Uthra
AU - Jialal, Ishwarlal
PY - 2014/11/1
Y1 - 2014/11/1
N2 - OBJECTIVES: Insulin autoimmune syndrome (IAS) is an extremely rare cause of hypoglycemia, particularly in non-Asian populations.METHODS: In this report, we describe a white male patient with elevated total insulin (>100.0 μIU/mL), C-peptide, and proinsulin levels who was diagnosed with IAS due to anti-insulin antibodies. He also had a small IgG κ M-protein.RESULTS: We show that anti-insulin antibodies and/or the monoclonal protein can significantly interfere with insulin and C-peptide immunoassays and propose polyethylene glycol precipitation to quantitate free C-peptide levels as a useful assay in differentiating IAS due to anti-insulin antibodies from insulinoma.CONCLUSIONS: In patients presenting with hypoglycemia with excessively high insulin levels, consideration needs to be given to autoimmune hypoglycemia due to anti-insulin antibodies as a cause. Additionally, if total C-peptide levels are increased, free C-peptide needs to be quantitated following polyethylene glycol precipitation.
AB - OBJECTIVES: Insulin autoimmune syndrome (IAS) is an extremely rare cause of hypoglycemia, particularly in non-Asian populations.METHODS: In this report, we describe a white male patient with elevated total insulin (>100.0 μIU/mL), C-peptide, and proinsulin levels who was diagnosed with IAS due to anti-insulin antibodies. He also had a small IgG κ M-protein.RESULTS: We show that anti-insulin antibodies and/or the monoclonal protein can significantly interfere with insulin and C-peptide immunoassays and propose polyethylene glycol precipitation to quantitate free C-peptide levels as a useful assay in differentiating IAS due to anti-insulin antibodies from insulinoma.CONCLUSIONS: In patients presenting with hypoglycemia with excessively high insulin levels, consideration needs to be given to autoimmune hypoglycemia due to anti-insulin antibodies as a cause. Additionally, if total C-peptide levels are increased, free C-peptide needs to be quantitated following polyethylene glycol precipitation.
KW - Anti-insulin antibodies
KW - Autoimmune hypoglycemia syndrome
KW - Free C-peptide assay
KW - Hirata disease
KW - Insulin autoimmune syndrome
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U2 - 10.1309/AJCPX56JQBJHUBGJ
DO - 10.1309/AJCPX56JQBJHUBGJ
M3 - Article
C2 - 25319986
AN - SCOPUS:84922211211
VL - 142
SP - 689
EP - 693
JO - American Journal of Clinical Pathology
JF - American Journal of Clinical Pathology
SN - 0002-9173
IS - 5
ER -