## Core Concept
Thiazide diuretics are a class of **diuretics** that act on the **distal convoluted tubule** of the kidneys, inhibiting **sodium-chloride symporter** and thus promoting the excretion of sodium and chloride. This action results in increased urine production and is used to treat **hypertension** and **edema**.

## Why the Correct Answer is Right
Thiazide diuretics work by inhibiting the **sodium-chloride cotransporter** in the distal convoluted tubule. This mechanism leads to several therapeutic and adverse effects. The therapeutic effect is a decrease in blood pressure and reduction of fluid volume. However, one notable adverse effect is **hypokalemia** (low potassium levels), which occurs because of increased potassium excretion in the collecting ducts.

## Why Each Wrong Option is Incorrect
- **Option A:** Thiazides can cause **hypercalcemia** (elevated calcium levels) as an adverse effect because they decrease calcium excretion.
- **Option B:** Thiazides are known to cause **hypokalemia** (low potassium levels) due to increased potassium secretion in the collecting ducts.
- **Option D:** Thiazides can lead to **hyperuricemia** (elevated uric acid levels) because they decrease uric acid excretion.

## Clinical Pearl / High-Yield Fact
A key clinical point to remember is that thiazide diuretics can cause **metabolic alkalosis** and **hypokalemia**. To mitigate **hypokalemia**, potassium supplements or potassium-sparing diuretics are often used concomitantly.

## Correct Answer Line
**Correct Answer: C.**