Question:medium
A female patient on lithium for bipolar disorder for 6 months fasted for several days for religious reasons and later presented with seizures, tremors, confusion and weakness. Which investigation should be done to diagnose her condition?
A female patient on lithium for bipolar disorder for 6 months fasted for several days for religious reasons and later presented with seizures, tremors, confusion and weakness. Which investigation should be done to diagnose her condition?
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Dehydration plus a narrow-index drug: measure the drug itself.
Updated On: Jun 23, 2026
- Serum electrolytes
- Serum lithium
- ECG
- MRI
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The Correct Option is B
Solution and Explanation
Connect the dots: a patient on lithium, then days of fasting and volume depletion, then neurological symptoms. Dehydration cuts sodium intake, the kidney reabsorbs more lithium to compensate, and serum lithium climbs into the toxic zone, producing tremor, confusion, weakness and seizures. The question asks how to diagnose her condition, so you want the most specific test, which is the serum lithium level. Electrolytes and an ECG help assess the consequences and complications but do not pin the diagnosis, and an MRI has no role in confirming lithium toxicity. The diagnostic investigation is serum lithium.
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