Psychiatry — USMLE Step 3 Practice
Psychiatry on USMLE Step 3 covers diagnosis and management of mood disorders, psychosis, anxiety disorders, substance use, and psychiatric emergencies. Pharmacological side effect profiles are heavily tested.
Frequently Asked Questions
How do you differentiate major depression from bipolar disorder on Step 3?
Major depressive disorder: depressive episodes only. Bipolar I: at least one manic episode (elevated/irritable mood, decreased sleep, grandiosity, increased activity, impulsivity, lasting >7 days or requiring hospitalization). Bipolar II: hypomanic episodes + depression. Key: antidepressant monotherapy can precipitate mania in undiagnosed bipolar — screen before prescribing.
What are the first-line treatments for schizophrenia on USMLE Step 3?
Atypical (second-generation) antipsychotics are first-line: risperidone, olanzapine, quetiapine, aripiprazole, ziprasidone. Clozapine is reserved for treatment-resistant schizophrenia (requires CBC monitoring for agranulocytosis). Long-acting injectable antipsychotics improve adherence for patients with frequent relapses.
What are the neuroleptic malignant syndrome features and treatment?
NMS: hyperthermia (often >40°C), severe muscle rigidity ('lead pipe'), altered consciousness, autonomic instability (labile BP, tachycardia, diaphoresis), elevated CK. Stop antipsychotic immediately. Treatment: IV fluids, dantrolene (muscle relaxant), bromocriptine (dopamine agonist), cooling measures. Can be fatal if untreated.
What is the Step 3 approach to acute alcohol withdrawal?
Alcohol withdrawal timeline: tremors/anxiety (6-24h) → seizures (12-48h) → delirium tremens (48-96h — autonomic instability, hallucinations, mortality risk). CIWA scale guides treatment. Benzodiazepines (lorazepam, diazepam, chlordiazepoxide) are first-line. Thiamine 100 mg IV before any glucose to prevent Wernicke encephalopathy.
When is involuntary psychiatric hospitalization indicated on Step 3?
Involuntary commitment requires: danger to self (active suicidal ideation with plan/intent or recent attempt), danger to others (credible threat of violence toward identifiable person), or grave disability (unable to provide self-care due to mental illness). Physician evaluation required; commitment varies by state law.
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