Write a short note on bipolar disorder, including lithium therapy and its monitoring.

Definition & Types

Bipolar disorder is a chronic mood disorder characterised by recurrent episodes of mania or hypomania alternating with depression, with intervening periods of relative normality. Lifetime prevalence is about 1%, affecting men and women equally, with onset typically in the late teens or early twenties.

Clinical Features of Mania

Elevated, expansive or irritable mood is the core feature. Severe mania may include mood-congruent grandiose or persecutory delusions and, rarely, hallucinations. Insight is characteristically absent, which is why patients resist treatment and admission is often necessary.

Aetiology

Strongly genetic — heritability of 70–80%, the highest of the major psychiatric disorders; concordance in monozygotic twins is 40–70%. Neurochemically, mania is associated with excess dopamine and noradrenaline. Precipitants include sleep deprivation, childbirth, stimulant or steroid use, and antidepressants given without a mood stabiliser (antidepressant-induced switch).

Management

Acute mania:

• Atypical antipsychotic (olanzapine, risperidone, quetiapine, aripiprazole) — rapid control of agitation and psychosis.
• Mood stabiliser — lithium or sodium valproate (valproate acts faster in acute mania).
• Benzodiazepine short-term for agitation and to restore sleep.
• Stop any antidepressant. Admit if there is risk to self, reputation or finances, or if insight is absent.
• ECT for severe, treatment-resistant mania or where physical exhaustion threatens life.

Bipolar depression: quetiapine, olanzapine–fluoxetine combination, or lamotrigine. Antidepressant monotherapy is avoided — it risks precipitating a switch to mania or inducing rapid cycling.

Maintenance: lithium is the mood stabiliser of choice and the only agent with clear evidence of reducing suicide risk. Alternatives are valproate, lamotrigine (better for depressive relapse) and atypical antipsychotics. Combine with psychoeducation, regular sleep-wake routine, and relapse-signature recognition.

Lithium — the Examination Focus

• Narrow therapeutic index, requiring serum level monitoring 12 hours after the evening dose.
• Baseline before starting: renal function, thyroid function, calcium, ECG and pregnancy test.
• Monitoring: levels weekly until stable then every 3 months; renal and thyroid function every 6 months.
• Adverse effects: fine tremor, polyuria and polydipsia (nephrogenic diabetes insipidus), hypothyroidism, weight gain, acne, and long-term chronic interstitial nephritis. Ebstein's anomaly with first-trimester exposure.
• Toxicity is precipitated by dehydration, NSAIDs, thiazide diuretics and ACE inhibitors, and any cause of renal impairment.