INTRODUCTION:In critically ill patients, symptoms and signs might be masked by different disease processes. The use of insulin drips and tight glucose control mandates accurate bedside glucose measurements. A high level of awareness to the possibility of overestimated glucose levels by glucometers is warranted. We present a case of an overestimated glucose level resulting in a near fatal result.
CASE PRESENTATION:A 30 year-old male with a history of coronary artery disease, coronary artery bypass graft surgery, end-stage renal disease (ESRD) on peritoneal dialysis and diabetes mellitus presents to the emergency department with two days of hematemesis. He reports compliance with all medications as well as peritoneal dialysis.Following admission, repeat laboratory data showed a developing metabolic gap acidosis with elevated glucose and the presence of acetones. He was diagnosed with diabetic ketoacidosis and an insulin drip was initiated. In the morning of hospital day two, the patient was noted to be obtunded and uncommunicative. His vital signs were within normal limits and physical examination was otherwise unremarkable. Bedside glucose testing showed a value of 188 in two separate measurements. Because of a strong suspicion for hypoglycemia after blood was drawn for a basic metabolic panel (BMP), 20mL of 50% dextrose was administered intravenously. The patient’s mental status quickly returned to normal. It was later discovered that the patient had dwelling of peritoneal dialysate for more than 24 hours prior to admission. The BMP sent during the episode revealed serum glucose of 18mg%.
DISCUSSIONS:Hypoglycemia, frequently encountered in the intensive care units and emergency departments is a life threatening, yet easily treatable condition. The use of hand-held glucometers has made diagnosing the condition easy and prompt, thus allowing for quick response in administering glucose. Diabetes mellitus is a risk factor for renal impairment and end stage renal disease requiring dialysis. Peritoneal dialysis (PD) uses a glucose-based dialysate for ultrafiltration, however, overtime, structural changes in the mesothelium lead to a reduced effect of the PD. Icodextrin, a cornstarch derived glucose polymer, allows for higher concentrations and improves ultrafiltration. It is also used in other types of medication such as chemotherapy. When used in PD fluid, 20-30% of the icodextrin is absorbed to the systemic circulation and is metabolized to oligosaccharides such as maltose, maltotriose and maltotetrose. Theses metabolites are not available to the human cells as a source of glucose. Icodextrin metabolites, especially maltose, can react with some glucometer enzymatic reactions to give falsely high results. Most glucometers use an enzymatic reaction of either glucose oxidase (GOD) or glucose dehydrogenase (GDH). It is generally thought that the GDH method is more susceptible to icodextrin metabolites1. However, in one small study2 it was shown that glucometers using both methods show interference. In the case we presented the patient results of the serum levels show beyond doubt that there was significant interference with the glucometer reading. Icodextrin and its metabolites are removed by the kidney, and in case of ESRD by dialysis. Therefore, the interference with the glucometer measurements can continue for a significant period of time.
CONCLUSION:When used in peritoneal dialysis, icodextrin can lead to overestimated blood glucose levels as measured by bedside glucometers. Caregivers should be aware of this possibility in cases of peritoneal dialysis and other treatments containing icodextrin.
DISCLOSURE:Daniel King, No Financial Disclosure Information; No Product/Research Disclosure Information