What happens to lithium levels in blood when used with hydrochlorothiazide?
**Core Concept**
Lithium is a narrow therapeutic index medication used in the management of bipolar disorder. Its plasma levels are tightly regulated due to the risk of toxicity. Hydrochlorothiazide, a thiazide diuretic, is commonly used to treat hypertension. The interaction between lithium and hydrochlorothiazide is crucial to understand in clinical practice.
**Why the Correct Answer is Right**
When hydrochlorothiazide is used with lithium, it leads to increased lithium levels in the blood. This is due to the decreased renal clearance of lithium caused by hydrochlorothiazide-induced hypovolemia and decreased glomerular filtration rate. As a result, the kidneys reabsorb more lithium, leading to higher plasma concentrations. This can increase the risk of lithium toxicity.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not accurately describe the effect of hydrochlorothiazide on lithium levels.
**Option B:** This option is incorrect because it implies a decrease in lithium levels, which is not the case when hydrochlorothiazide is used.
**Option C:** This option is incorrect because it suggests a neutral effect on lithium levels, which is not true when hydrochlorothiazide is used.
**Clinical Pearl / High-Yield Fact**
When using lithium with hydrochlorothiazide, patients should be closely monitored for signs of lithium toxicity, such as tremors, confusion, and ataxia. It is essential to adjust the lithium dose or consider alternative antihypertensive agents to minimize the risk of toxicity.
**Correct Answer:** B. Lithium levels increase in the blood when used with hydrochlorothiazide.