To reduce the risk of lithium toxicity in the setting of dehydration, which actions are recommended?

• A. Drink about 2 liters of fluids daily and ensure adequate salt; avoid NSAIDs and thiazides
• B. Drink no fluids
• C. Increase caffeine
• D. Increase salt restriction

Answer: (A)

Staying hydrated and maintaining salt balance is crucial because lithium is cleared by the kidneys in a way that is highly sensitive to sodium and fluid status. When you’re dehydrated, the kidneys reabsorb more lithium along with sodium, which raises lithium levels and increases the risk of toxicity. Drinking about 2 liters of fluids daily helps keep urine output adequate and reduces this reabsorption. Keeping an adequate amount of salt is important because with normal sodium levels, lithium is excreted more effectively; if sodium is low, the kidneys grab more lithium to conserve sodium, worsening toxicity risk.

Certain medications can push lithium levels up. NSAIDs reduce kidney blood flow and can increase lithium retention, while thiazide diuretics promote sodium loss and further increase lithium reabsorption. That’s why they’re avoided in this context.

Less appropriate choices would worsen dehydration or promote lithium retention: not drinking fluids would raise toxicity risk; caffeine can act as a diuretic and worsen dehydration; and restricting salt would promote lithium reabsorption and toxicity.