A bipolar patient on lithium who has been started on bendroflumethiazide presents with nausea and tremors. What is the most appropriate action?

• A. Refer urgently to the prescriber for possible lithium toxicity
• B. Stop bendroflumethiazide and monitor
• C. Decrease lithium dose
• D. Increase fluids

Answer: (A)

Lithium levels can rise when a thiazide diuretic is added, because thiazides reduce renal lithium clearance and often cause volume depletion, which increases lithium reabsorption in the kidneys. When lithium toxicity begins, early signs commonly include nausea and tremor, and these can progress to confusion, ataxia, or seizures if not managed promptly.

Because the patient on lithium has just started bendroflumethiazide and is now experiencing symptoms that fit lithium toxicity, the most appropriate action is to refer urgently to the prescriber for assessment and potential management. The prescriber may decide to stop or adjust the interacting diuretic, modify the lithium dose, or initiate appropriate monitoring and treatment, possibly including hospital evaluation if toxicity is suspected.

Do not make changes to the regimen yourself. Increasing fluids might help with dehydration but won’t correct elevated lithium levels, and decreasing lithium or stopping the diuretic without medical supervision could worsen the situation or cause other problems. If symptoms worsen (confusion, drowsiness, seizures), seek urgent medical care immediately.