**Core Concept**
Thiazide diuretics are a class of medications used to treat hypertension and edema. They work by inhibiting the sodium-chloride cotransporter in the distal convoluted tubule of the kidneys, leading to increased sodium and water excretion.

**Why the Correct Answer is Right**
Thiazides cause increased potassium excretion by stimulating the sodium-potassium-chloride cotransporter in the cortical collecting duct. This leads to a decrease in serum potassium levels, a common side effect of thiazide therapy. The mechanism involves competition between thiazides and potassium ions for the sodium-potassium-chloride cotransporter, resulting in increased potassium excretion.

**Why Each Wrong Option is Incorrect**
* **Option A:** Not applicable, as we are looking for a side effect of thiazides.
* **Option B:** This option is incorrect because thiazides can actually increase calcium reabsorption in the kidneys, leading to hypercalcemia in some cases.
* **Option C:** This option is incorrect because thiazides are not typically associated with increased glucose excretion.

**Clinical Pearl / High-Yield Fact**
It's essential to monitor serum potassium levels in patients taking thiazides, especially in those with pre-existing hypokalemia or those taking other medications that can exacerbate potassium loss.

**Correct Answer: B. This option is incorrect because thiazides can actually increase calcium reabsorption in the kidneys, leading to hypercalcemia in some cases.**