Which statement describes a major nursing consideration for patients on lithium therapy for bipolar disorder?

• A. Narrow therapeutic index; monitor renal function, thyroid function, and ensure consistent salt and fluid intake.
• B. Lithium requires a high-fat diet and weekly liver function tests.
• C. Lithium has a wide therapeutic window and no routine labs are needed.
• D. Lithium use does not require monitoring once symptoms stabilize.

Answer: (C)

Lithium has a narrow therapeutic index, so careful monitoring is essential. Small changes in dose, kidney function, hydration, or electrolyte balance can quickly move levels from therapeutic to toxic. Because lithium is cleared by the kidneys and can affect both renal and thyroid function, routine labs are necessary: habitual checks of serum lithium levels to stay within the effective range, plus periodic renal function tests and thyroid function tests. Maintaining consistent salt and fluid intake is also important because sodium competes with lithium for renal reabsorption; dehydration or significant changes in sodium intake can raise lithium levels and increase toxicity risk. In practice, nurses prioritize ensuring adequate hydration, monitoring lab results, watching for early signs of toxicity (such as tremor, confusion, ataxia, GI symptoms), and educating patients about adhering to monitoring and hydration recommendations.