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This is a clinician-written, evidence-based summary aligned to the USMLE Step 2 CK Content Outline. It is intended for medical students preparing for USMLE Step 2 CK. Management reflects current ACC/AHA, USPSTF, and APA guidelines. Always cross-reference with UpToDate, institutional protocols, and clinical judgment.
The Bottom Line
- Bipolar I = at least one manic episode; bipolar II = hypomania + major depressive episode without mania
- Mania lasts >=1 week or any duration if hospitalized or psychotic; hypomania lasts >=4 days and does not cause marked impairment or psychosis
- Acute mania: lithium or valproate plus an antipsychotic when severe, psychotic, or agitated
- Never treat bipolar depression with antidepressant monotherapy
- Lithium reduces suicide risk but requires renal, thyroid, calcium, pregnancy, and interaction monitoring
Overview
Bipolar disorder is defined by episodes of mania or hypomania. Mania is abnormally elevated, expansive, or irritable mood with increased energy and at least 3 additional symptoms: grandiosity, decreased need for sleep, pressured speech, flight of ideas, distractibility, increased goal-directed activity, or risky behavior. Psychosis during an elevated mood episode makes it mania rather than hypomania. Bipolar depression often presents first and is easily mistaken for unipolar depression unless clinicians ask about past elevated-energy episodes.
Epidemiology
Bipolar disorder usually begins in late adolescence or early adulthood. Risk factors include family history, postpartum period, antidepressant exposure in susceptible individuals, sleep deprivation, stimulant or corticosteroid use, and substance use. Suicide risk is high, particularly during depressive or mixed episodes.
Clinical Features
Symptoms
Decreased need for sleep with preserved or increased energy
Grandiosity, increased confidence, pressured speech, racing thoughts
Distractibility, increased goal-directed activity, psychomotor agitation
Impulsive spending, sexual risk-taking, reckless driving, or sudden business schemes
Psychosis, severe agitation, aggression, or inability to care for self
Depressive episodes with atypical features or antidepressant-induced activation
Signs
Rapid, loud, difficult-to-interrupt speech and psychomotor agitation
Expansive, irritable, labile, or euphoric affect
Poor insight, disinhibition, intrusive behavior, or unsafe impulsivity
Signs of intoxication, stimulant use, hyperthyroidism, or delirium
Investigations
First-line
DSM-5-TR clinical assessmentDetermine mania, hypomania, depression, mixed features, psychosis, catatonia, functional impairment, and episode timing
Safety assessmentAssess suicide, violence, grave disability, psychosis, access to weapons, sleep deprivation, and ability to eat/drink
Medical/substance screenTSH, CMP, CBC, urine toxicology, pregnancy test, and review steroids, stimulants, antidepressants, or dopaminergic drugs
Second-line
Baseline labs before mood stabilizersLithium: BMP/creatinine, TSH, calcium, pregnancy test, ECG if cardiac risk; valproate: LFTs, CBC/platelets, pregnancy test
Collateral historyFamily or records often clarify duration, sleep, impairment, and prior episodes
Comorbidity screenAlcohol/stimulant use, panic disorder, PTSD, ADHD, and personality disorder traits
Specialist
Psychiatry referralFirst manic episode, psychosis, mixed features, pregnancy, suicidality, rapid cycling, diagnostic uncertainty, or complex pharmacology
1
Acute mania or mixed episode
- Hospitalize if psychotic, suicidal, violent, gravely disabled, or unable to sleep/eat safely
- Start lithium or valproate; add an atypical antipsychotic such as risperidone, olanzapine, quetiapine, or aripiprazole for severe mania or psychosis
- Use benzodiazepines short-term for agitation/insomnia while mood stabilizer takes effect; hold antidepressants and stimulants
2
Bipolar depression
- Options include quetiapine, lurasidone with lithium/valproate, lamotrigine, or lithium depending on history and polarity
- Avoid antidepressant monotherapy; if used, pair with a mood stabilizer and avoid in mixed features or rapid cycling
- ECT for severe suicidality, catatonia, psychosis, pregnancy with severe illness, or treatment resistance
3
Maintenance and safety
- Lithium prevents relapse and lowers suicide risk; monitor trough, renal function, thyroid function, calcium, pregnancy, and interactions
- Valproate helps mania/mixed states but is teratogenic; avoid in pregnancy when possible
- Lamotrigine prevents bipolar depression but is not an acute antimanic drug; titrate slowly due to Stevens-Johnson syndrome risk
Complications
- Suicide, especially in depressive and mixed episodes:
- Psychosis during mania or depression:
- Substance use causing relapse and diagnostic confusion:
- Legal, financial, sexual, and occupational harm from impulsivity:
- Lithium toxicity, nephrogenic DI, hypothyroidism; valproate hepatotoxicity and teratogenicity:
USMLE Step 2 CK Exam Tips
- 1Mania requires >=1 week unless hospitalized or psychotic; psychosis means mania, not hypomania
- 2Decreased need for sleep is more specific than insomnia
- 3Antidepressant-induced mania: stop antidepressant and start mood stabilizer/antipsychotic
- 4Acute severe mania with psychosis: antipsychotic + lithium or valproate
- 5Lithium toxicity: coarse tremor, vomiting, diarrhea, ataxia, confusion; severe cases need hemodialysis
- 6Lamotrigine is for bipolar depression maintenance, not acute mania
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