A 28-year-old woman presents to the clinic complaining of feeling "down" and "exhausted" f… — USMLE Step 2 CK

A 28-year-old woman presents to the clinic complaining of feeling "down" and "exhausted" for the past month. She reports struggling to get out of bed, losing interest in her hobbies, and experiencing a 3-kg (6.6-lb) weight gain. She has difficulty concentrating at work. Four years ago, she had a period lasting about a week where she felt "on top of the world," required only 3 hours of sleep a night, and started a business that quickly failed, accumulating significant debt. She is currently not taking any medications. Her vital signs are temperature 37.0°C (98.6°F), blood pressure 110/70 mm Hg, pulse 72/min, and respirations 14/min. Physical examination shows no abnormalities. Laboratory studies show a thyroid-stimulating hormone (TSH) level of $2.1 \text{ mU/L}$ and a free thyroxine (T4) level of $1.2 \text{ ng/dL}$ . Which of the following is the most appropriate initial pharmacotherapy for this patient?

QuetiapineAnswer
B
Escitalopram
C
Venlafaxine
D
Amitriptyline
E
Levothyroxine

Answer

Quetiapine

The correct answer is quetiapine. This patient presents with a major depressive episode, but her history of a distinct period of abnormally elevated mood, decreased need for sleep, and risky financial behavior lasting a week meets the criteria for a manic episode. Therefore, her diagnosis is bipolar I disorder, currently in a depressed episode. The first-line treatment for bipolar depression includes certain second-generation antipsychotics (e.g., quetiapine, lurasidone) or mood stabilizers (e.g., lithium, lamotrigine). Quetiapine effectively treats the depressive symptoms without significantly increasing the risk of a manic switch.

Step-by-Step Solution

Analyze the patient's current symptoms.

The patient has a 1-month history of depressed mood, fatigue, anhedonia, weight gain, and poor concentration, which are indicative of a major depressive episode.

To establish the current clinical state.

Review the patient's psychiatric history.

The patient had a 1-week episode of elevated mood, decreased need for sleep, and risky behavior 4 years ago.

To determine if the patient has a history of mania or hypomania, which fundamentally alters the diagnosis and management.

Synthesize the findings to formulate a diagnosis.

A history of a manic episode combined with a current major depressive episode is diagnostic of Bipolar I disorder, currently in a depressed episode.

To guide the selection of appropriate pharmacotherapy.

Select the appropriate treatment for bipolar depression.

Quetiapine is selected as it is approved for the treatment of bipolar depression and does not carry a high risk of inducing a manic switch.

Antidepressant monotherapy must be avoided in bipolar disorder due to the significant risk of precipitating mania.

Key Concept

Patients presenting with a major depressive episode must be carefully screened for a history of mania or hypomania to rule out bipolar disorder before initiating therapy, as antidepressant monotherapy can precipitate a manic switch.

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