MON-699 Artifactual Hypoglycemia in a Patient with Prolonged Hospital Stay for Neuroleptic Malignant Syndrome

Background: Hypoglycemia is rare in patients without diabetes. A low capillary glucose concentration is not sufficient to make a diagnosis of a hypoglycemic disorder. In fact, this has multiple sources of error. Fulfillment of Whipple’s triad is an essential step for establishing the diagnosis of a hypoglycemic disorder. Clinical case: A 47-year old Caucasian male with past medical history of paranoid schizophrenia was admitted to the ICU from an outside facility with catatonia and apneic spells following an acute change in mental status. He was diagnosed with neuroleptic malignant syndrome and Endocrinology was consulted after 137 days in the hospital for concerns of severe and recurrent hypoglycemia. The patient was non-verbal on evaluation and despite multiple capillary blood glucose readings of <70 mg/dL, including measurements as low as 29 mg/dL, he remained asymptomatic with absence of any clinical signs of an adrenergic response to hypoglycemic episodes. He was on continuous tube feeding through a PEG tube. The low capillary blood glucose measurements prompted rapid management with intravenous or oral dextrose based on the hypoglycemia protocol designed by the hospital. As a last resort, the patient was placed on a continuous dextrose infusion in addition to tube feeding to prevent hypoglycemia.Diagnostic evaluation: Following consultation, we ordered for a corresponding plasma glucose measurement to be done with any capillary blood glucose measurement of < 55 mg/dL prior to correction for hypoglycemia. For a capillary blood glucose measured at 48 mg/dL, corresponding plasma glucose was 95 mg/dL. Whipple’s triad was not fulfilled and no additional work up was pursued. We recommended calibration of the glucose monitors for the hospital unit where the patient was admitted with recommendations to stop monitoring capillary blood glucose in this patient in the absence of diabetes, signs/symptoms of hypoglycemia, medications implicated to cause hypoglycemia and ongoing nutrition with tube feeding. Follow-up: The patient remains in the hospital and is waiting placement at an extended care facility. Plasma blood glucose measurements remain within normal range.Clinical lesson: Artifactual hypoglycemia, though uncommon, is an important consideration when evaluating and managing hypoglycemia. Whipple’s triad is essential to make a diagnosis of true hypoglycemia. Several factors; patient, operator and machine-related, can impact measurements of capillary blood glucose measurements and often result in unnecessary treatment measures often causing inefficient and often preventable wastage of hospital resources and sometimes even harm the patient.