Undetected Exogenous Insulin Administration in a Child: Assessment of Assay Limitations and Impact on the Practice of Laboratory Medicine

Abstract Introduction/Objective The development of new synthetic insulin analogues over the past few decades has significantly impacted the management of hypoglycemia. However, accurately measuring these analogues presents challenges due to variable cross-reactivity with many insulin assays. Failure to consider cross-reactivity may lead to the misdiagnosis of exogenous insulin administration. Methods/Case Report A 13-year-old female with a history of type 1 DM was presented to an outside hospital emergency department with symptoms indicative of hypoglycemia. Multiple child protective services (CPS) referrals are noted. The patient had experienced several episodes of hypoglycemia over the prior week with blood glucose in the 30-40 mg/dL range. There were no associated symptoms of diarrhea, emesis, or fatigue. The patient was transferred to a pediatric hospital were preliminary investigations indicated abnormally low blood glucose levels with low insulin and C-peptide levels. Further evaluation was initiated to determine the underlying cause of these episodes and to ensure appropriate adjustments in insulin dosing and regimen. Initially, the Elecsys insulin assay (Roche Diagnostics) was utilized to quantify insulin levels which shows a low cross-reactivity for insulin lispro and glargine. To validate the hypothesis of an undetected exogenous insulin overdose, blood samples were sent to another laboratory employing The Advia Centaur insulin assay (Siemens) which exhibits a higher cross-reactivity for insulin lispro and glargine (89%-143%, respectively), indicating a higher recognition and measurement sensitivity for these insulin analogues. The analysis using this assay revealed significantly elevated insulin levels, corroborating the presence of an insulin overdose. The sample at the time of presentation at the outside hospital was confirmed to be 434.1 mU/L. A sample collected 17 hours later had an insulin level of 23.5 mU/L. Results (if a Case Study enter NA) NA Conclusion This case study highlights the critical issue of undetected insulin overdose in a child and emphasizes the limitations of the initial insulin assay employed. Improving assay sensitivity and reliability will enhance patient care and safety. This case study reminds clinicians and laboratory professionals of the need for ongoing quality assurance and vigilance in their practices.