A 40-year-old man is brought to the emergency department for sudden onset of headaches, diaphoresis, and loss of consciousness. His wife states that he was previously in his usual state of health. His past medical history is unremarkable. He works as a physician assistant and does not smoke or drink alcohol. On physical examination, the patient is diaphoretic and comatose. His fingerstick blood glucose level is 45 mg/dL. The patient is given 50% dextrose intravenously and then regains consciousness. He says that he is currently dealing with a great deal of work- and relationship-related stress. Laboratory test results on the blood sample drawn prior to dextrose administration are as follows:
Which of the following is the best next step in management of this patient?

Question

A 40-year-old man is brought to the emergency department for sudden onset of headaches, diaphoresis, and loss of consciousness.  His wife states that he was previously in his usual state of health.  His past medical history is unremarkable.  He works as a physician assistant and does not smoke or drink alcohol.  On physical examination, the patient is diaphoretic and comatose.  His fingerstick blood glucose level is 45 mg/dL.  The patient is given 50% dextrose intravenously and then regains consciousness.  He says that he is currently dealing with a great deal of work- and relationship-related stress. Laboratory test results on the blood sample drawn prior to dextrose administration are as follows:
 Which of the following is the best next step in management of this patient?

Quizplus · Accepted Answer

Explanation: 11ec2b69_becb_cbb4_8f63_0b481471e18a_MD0005_00 This patient has the classic Whipple's triad of symptomatic hypoglycemia - symptoms consistent with hypoglycemia, low blood glucose, and symptom resolution after glucose administration. Elevated insulin, C-peptide, and proinsulin levels indicate hypoglycemia due to endogenous insulin secretion, either from an insulinoma or surreptitious use of oral hypoglycemic medication (rather than an insulin injection). True spontaneous hypoglycemia is uncommon and insulinoma is relatively rare. As a result, sulfonylurea and/or meglitinide use should be suspected given that the patient works in healthcare and may have access to prescription medications. The first step to differentiate insulinoma from surreptitious medication ingestion is to obtain a serum assay for oral hypoglycemic agents. If no medications are detected, insulinoma becomes more likely, and ultrasound or CT imaging can localize the tumor for subsequent surgical resection (Choice B). The following principles should guide the evaluation of hypoglycemia: Whipple's triad must be fulfilled before a hypoglycemia workup is initiated. Many normal individuals may have blood glucose in the nominal hypoglycemic range without symptoms of hypoglycemia. Low blood glucose in normal individuals will suppress production of insulin, C-peptide, and proinsulin. In the presence of significant hypoglycemia, normal levels of these hormones indicate an abnormal response. Fingerstick blood glucose measurement is unreliable in the hypoglycemic range. Low blood glucose recorded by a bedside glucometer must be confirmed by a standard laboratory assay. Blood samples for biochemical testing must be taken when the patient is hypoglycemic and before glucose administration. (Choice A) When a patient is in a normoglycemic state but is suspected to have a hypoglycemic disorder, a 72-hour fasting test is done to induce hypoglycemia. Patients with an insulinoma will continue to have high or inappropriately normal insulin levels despite a prolonged fast. However, this patient has confirmed hypoglycemia with elevated serum insulin, so prolonged fasting is unnecessary. (Choice C) C-peptide is a by-product of endogenous insulin secretion. Normal or elevated C-peptide levels confirm ongoing insulin production. Surreptitious insulin injection elevates plasma insulin but C-peptide remains low. (Choice D) The mixed-meal challenge test is used for evaluating patients with hypoglycemic symptoms that only occur after eating. Educational objective: Patients exhibiting Whipple's triad - symptoms consistent with hypoglycemia, low blood glucose, and symptom resolution following glucose administration - should be evaluated for a hypoglycemic disorder. A serum assay for oral hypoglycemic agents and serum levels of insulin, C-peptide, and proinsulin can generally determine the likely cause. The blood sample should be drawn during the hypoglycemic episode. References: Evaluation and management of adult hypoglycemic disorders: An Endocrine Society clinical practice guideline. (http://www.ncbi.nlm.nih.gov/pubmed/19088155)

A 40-Year-Old Man Is Brought to the Emergency Department for Sudden