Avoiding Unnecessary Repeat Laboratory Testing

We present a 44-year-old Caucasian female with a history of diabetes mellitus admitted to the intensive care unit (ICU) for refractory hypoglycemia with an initial blood glucose of 39 mg/dl. The initial evaluation included a random insulin level, C-peptide, Hemoglobin A1c, and a sulfonylurea screen that were ordered when the patient's blood sugar was 39 mg/dL. She was discharged after demonstrating euglycemia. The test results for sulfonylurea screen, insulin, and C-peptide levels were obtained one day after discharge. The insulin level was elevated, and C-peptide was inappropriately low, establishing the diagnosis of surreptitious exogenous insulin use. Four days after discharge, the patient was readmitted to the same ICU with a similar presentation of refractory hypoglycemia. Once again, the sulfonylurea screen, along with the insulin and C-peptide levels were ordered as there was no mention of the previously obtained results in the discharge summary. The discrepancy between random insulin and C-peptide levels reaffirmed the diagnosis of surreptitious exogenous use of insulin. As high-value medical care becomes a focal point in medicine, the costs, root causes, and impacts of inappropriate laboratory testing must be understood. Upwards of 25% of ordered laboratory tests are unnecessary. Physicians' failure to follow-up on results of correctly ordered tests and repeat testing despite established diagnosis is a significant cause of unneeded laboratory testing. Best practice guidelines recommend a reduction in unnecessary laboratory testing by implementing computer-based solutions to maximize the identification of duplicate requests and to promote clinical education at the time of laboratory test ordering.