A 25-year-old man is brought to the emergency department due to acute-onset dizziness, weakness, sweating, and confusion. The patient has a blood glucose level of 36 mg/dL, and his symptoms resolve with intravenous dextrose. He has no medical conditions and takes no medications. The patient has smoked intermittently for the last 5 years but does not use alcohol or illicit drugs. He is unemployed and lives with his parents. His father has type 2 diabetes mellitus and takes metformin and glyburide. His mother has hypertension treated with lisinopril.
Physical examination is unremarkable. The patient is hospitalized for observation. On the second day, he develops similar symptoms with a blood glucose level of 34 mg/dL; intravenous dextrose is again administered and his symptoms improve.
Laboratory results drawn during the second episode of hypoglycemia are as follows:
Which of the following is the best next step in evaluation of this patient?

Question

A 25-year-old man is brought to the emergency department due to acute-onset dizziness, weakness, sweating, and confusion.  The patient has a blood glucose level of 36 mg/dL, and his symptoms resolve with intravenous dextrose.  He has no medical conditions and takes no medications.  The patient has smoked intermittently for the last 5 years but does not use alcohol or illicit drugs.  He is unemployed and lives with his parents.  His father has type 2 diabetes mellitus and takes metformin and glyburide.  His mother has hypertension treated with lisinopril.
Physical examination is unremarkable.  The patient is hospitalized for observation.  On the second day, he develops similar symptoms with a blood glucose level of 34 mg/dL; intravenous dextrose is again administered and his symptoms improve.
Laboratory results drawn during the second episode of hypoglycemia are as follows:
 Which of the following is the best next step in evaluation of this patient?

Quizplus · Accepted Answer

11ec193a_95fd_0f3d_853d_7550a609545d_MD0002_00 This patient has symptomatic hypoglycemia and fulfills Whipple's triad (blood glucose <55 mg/dL, hypoglycemic symptoms, relief of symptoms with glucose administration). In addition, his contemporaneous insulin and C-peptide levels are at the upper limit of normal, suggesting that his hypoglycemia is due to excess release of endogenous insulin. In light of this patient's access to his father's glyburide, a possible explanation for his hypoglycemia is surreptitious sulfonylurea use. This should be confirmed with a hypoglycemic drug screen. Glyburide has a relatively long duration of action, and patients with intentional or inadvertent overdose can develop recurrent hypoglycemia and warrant extended observation for frequent glucose monitoring; alternately, the patient may be surreptitiously taking glyburide while in the hospital. (Choice A) Insulinomas can cause recurrent episodes of hypoglycemia with normal to high insulin and C-peptide levels. However, these tumors are rare and typically present at an older age. If the oral hypoglycemic drug screen is negative, further imaging (eg, abdominal CT scan) would be warranted. (Choices B and E) In patients with suspected but unconfirmed hypoglycemia, prolonged (eg, 72-hr) fasting may induce hypoglycemia and facilitate biochemical investigations. With prolonged fasting, hepatic glycogen stores are usually depleted and administration of glucagon ("glucagon challenge") normally causes only a small rise in blood glucose; a rise >25 mg/dL suggests that hepatic glycogen has been maintained due to inappropriate hyperinsulinemia. This patient has already had confirmed hypoglycemia, and a prolonged fast is not necessary. (Choice C) Antibodies acting on the insulin receptor or binding to insulin can result in hypoglycemia. However, this is very rare, and other causes should be ruled out first. Educational objective: Hypoglycemia in a nondiabetic patient requires further evaluation if all 3 criteria of Whipple's triad (blood glucose <55 mg/dL, hypoglycemic symptoms, relief of symptoms with glucose administration) are present. Surreptitious sulfonylurea use can cause hypoglycemia associated with elevated or inappropriately normal insulin and C-peptide levels. __________ References: Evaluation and management of adult hypoglycemic disorders: an Endocrine Society Clinical Practice Guideline. (http://www.ncbi.nlm.nih.gov/pubmed/19088155) Non-diabetic hypoglycemia. (http://www.ncbi.nlm.nih.gov/pubmed/27099902)

A 25-Year-Old Man Is Brought to the Emergency Department Due