**Question:** A patient was on lithium therapy for bipolar disorder for 6 months. She kept fast for few days due to religious reasons and presented with coarse tremors, abdominal pain, nausea, dizziness & confusion. Which of the following should be done to assess her condition?

A. Lithium level check
B. Renal function test
C. Liver function test
D. Electroencephalogram (EEG)

**Correct Answer:** A. Lithium level check

**Core Concept:** Lithium is a common medication used for the treatment of bipolar disorder. Lithium therapy works by stabilizing mood, reducing depressive episodes, and preventing suicide attempts. Lithium can cause side effects if its levels become too high or too low in the blood.

**Why the Correct Answer is Right:** When a patient on lithium therapy experiences symptoms like coarse tremors, abdominal pain, nausea, dizziness, and confusion, it is essential to evaluate the lithium level in the blood. High levels of lithium can lead to lithium toxicity, which results in these symptoms. Assessing lithium levels helps determine if the dose needs adjustment to prevent adverse effects and maintain therapeutic levels.

**Why Each Wrong Option is Incorrect:**

**A.** Lithium levels should be checked after 24-48 hours of lithium intake, not immediately after fasting. Fasting can lead to a decrease in lithium clearance, causing the levels to appear falsely elevated.

**B.** Renal function tests (RFTs) are performed to assess the function of the kidneys. Lithium toxicity causes nephrotoxicity, which may lead to impaired RFTs, but checking RFTs alone would not determine lithium levels in the blood.

**C.** Liver function tests (LFTs) are used to assess liver function. Lithium does not cause significant liver toxicity, so checking LFTs doesn't directly address lithium toxicity concerns.

**D.** An electroencephalogram (EEG) is used to evaluate the brain's electrical activity. Lithium toxicity effects are neurological, not related to brain function, so an EEG is not relevant in this context.

**Clinical Pearl:** Adequate monitoring of lithium levels is crucial in managing patients on lithium therapy. Regular lithium level checks help in adjusting the dose and prevent adverse effects. It is essential to differentiate between lithium toxicity and fasting-related changes in lithium levels before making any adjustments to the dosage.