A collegiate gymnast presents to the student health center for evaluation of a persistentl… — USMLE Step 2 CK

A collegiate gymnast presents to the student health center for evaluation of a persistently depressed mood, profound fatigue, and anhedonia over the past three months. During the interview, she expresses deep dissatisfaction with her body shape and an intense fear of gaining weight. Vital signs show a heart rate of $54 \text{ /min}$ and a blood pressure of $92/58 \text{ mm Hg}$ . Physical examination reveals a body mass index of $17.4 \text{ kg/m}^2$ , fine downy hair on her arms, and bilateral parotid gland enlargement. Laboratory results are notable for a serum potassium of $3.2 \text{ mEq/L}$ . She asks the physician to prescribe an antidepressant she read about online, describing it as 'the one that does not cause weight gain or sexual problems.' If the physician complies and prescribes this specific medication, the patient would be at significantly increased risk for which of the following complications?

A
QTc prolongation and torsades de pointes
B
Stevens-Johnson syndrome
Generalized seizuresAnswer
D
Agranulocytosis
E
Hypertensive crisis

Answer

Generalized seizures

The correct answer is generalized seizures. The patient's clinical presentation—including a low body mass index, bradycardia, lanugo (fine downy hair), parotid gland enlargement, and hypokalemia—is highly indicative of an eating disorder with purging behavior. She is requesting an antidepressant that is weight-neutral and lacks sexual side effects, which accurately describes bupropion. Bupropion is a norepinephrine-dopamine reuptake inhibitor (NDRI) that is known to lower the seizure threshold in a dose-dependent manner. It is absolutely contraindicated in patients with anorexia nervosa or bulimia nervosa. These conditions frequently cause severe electrolyte abnormalities (such as this patient's hypokalemia) that independently lower the seizure threshold, placing the patient at an extreme risk for developing generalized tonic-clonic seizures if bupropion is administered.

Step-by-Step Solution

Identify the patient's underlying psychiatric and medical condition based on the clinical presentation.

The patient has major depressive disorder comorbid with an eating disorder (anorexia nervosa, binge-eating/purging type), indicated by her low BMI, intense fear of weight gain, bradycardia, lanugo, parotid enlargement, and hypokalemia.

Recognizing the comorbid eating disorder and its physiologic consequences (electrolyte abnormalities) is crucial for safe psychopharmacologic selection.

Identify the specific medication the patient is requesting based on her description.

The medication requested is bupropion, a norepinephrine-dopamine reuptake inhibitor (NDRI).

Bupropion is uniquely known among antidepressants for being weight-neutral (or causing weight loss) and having an absence of sexual side effects.

Determine the primary adverse risk and contraindication of the requested medication in this specific patient population.

Bupropion causes a dose-dependent lowering of the seizure threshold and is therefore strictly contraindicated in patients with anorexia nervosa or bulimia nervosa.

Patients with eating disorders frequently suffer from electrolyte derangements (like this patient's hypokalemia) that independently lower the seizure threshold, making the administration of bupropion highly epileptogenic.

Key Concept

Bupropion is an activating antidepressant that lacks sexual side effects and does not cause weight gain, but it is strictly contraindicated in patients with eating disorders (anorexia and bulimia nervosa) due to an unacceptably high risk of generalized seizures.

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