A university student, aged 22, presents to the campus health center complaining of an 8-we… — USMLE Step 2 CK

A university student, aged 22, presents to the campus health center complaining of an 8-week history of profound melancholy, excessive sleepiness, and a complete inability to concentrate. She explains that she has stopped attending her lectures and feels devoid of any motivation. Review of her medical records reveals a prior psychiatric admission two years ago; during that time, she remained awake for six consecutive days, exhibited grandiose delusions about leading the university, and engaged in highly disruptive activities on campus before being hospitalized. She is currently not taking any medications. Recent thyroid function tests show a thyroid-stimulating hormone (TSH) level of $2.5 \mu\text{U/mL}$ (normal: $0.4-4.0 \mu\text{U/mL}$ ) and a free thyroxine ( $T_4$ ) level of $0.9 \text{ ng/dL}$ (normal: $0.8-1.8 \text{ ng/dL}$ ). She insists on being prescribed a medication to lift her mood so she can return to her studies. Which of the following is the most appropriate management plan for this patient?

Commence therapy with quetiapineAnswer
B
Prescribe escitalopram as a single agent
C
Start combination therapy with selegiline and fluoxetine
D
Prescribe levothyroxine to address an underlying secondary hypothyroidism
E
Notify the university dean to coordinate a mandatory medical absence

Answer

Commence therapy with quetiapine

The patient is currently presenting with a major depressive episode. However, her history of an episode characterized by decreased need for sleep, grandiosity, and hospitalization lasting six days unequivocally establishes a diagnosis of bipolar I disorder. The first-line pharmacological treatment for bipolar depression includes specific atypical antipsychotics (such as quetiapine or lurasidone) or mood stabilizers (such as lithium or lamotrigine). Quetiapine effectively treats the depressive symptoms without carrying the high risk of inducing a manic switch that is associated with standard antidepressants.

Step-by-Step Solution

Analyze the patient's current symptoms and duration.

The patient is experiencing a major depressive episode, characterized by 8 weeks of profound low mood, hypersomnia, and impaired concentration.

Establishing the current clinical syndrome is the first step in formulating a differential diagnosis.

Review the patient's past medical and psychiatric history.

The patient has a history of a discrete episode involving grandiosity, severe insomnia without fatigue, and disruptive behavior requiring hospitalization.

This historical event meets the full criteria for a manic episode, which changes the diagnosis from major depressive disorder to bipolar I disorder.

Evaluate the laboratory findings provided.

Both the TSH and free T4 levels fall within their respective normal reference ranges.

Normal thyroid function rules out an underlying endocrine etiology (such as hypothyroidism) for her depressive symptoms.

Select the safest and most effective pharmacotherapy for the established diagnosis.

Select an agent approved for bipolar depression, such as the atypical antipsychotic quetiapine.

In bipolar depression, standard antidepressant monotherapy must be avoided due to the risk of precipitating a manic switch. Mood stabilizers or specific atypical antipsychotics are indicated.

Key Concept

When evaluating a patient presenting with a major depressive episode, clinicians must meticulously screen for a history of mania or hypomania; the presence of a past manic episode confirms bipolar I disorder, requiring treatment with specific atypical antipsychotics or mood stabilizers rather than antidepressant monotherapy.

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