## **Core Concept**
The renal handling of glucose involves its reabsorption and excretion through specific mechanisms in the kidneys. Glucose reabsorption primarily occurs in the **proximal convoluted tubule (PCT)** of the nephron.

## **Why the Correct Answer is Right**
The correct answer, **proximal convoluted tubule (PCT)**, is where approximately 65-70% of glucose reabsorption occurs. This process is facilitated by **sodium-glucose cotransporters (SGLTs)**, specifically SGLT2, which are located in the apical membrane of the PCT cells. The reabsorbed glucose is then transported out of the cells into the bloodstream by **GLUT2** and **GLUT1** transporters.

## **Why Each Wrong Option is Incorrect**
- **Option A:** The **glomerulus** is involved in the filtration of blood, not the reabsorption of glucose. While glucose is filtered at the glomerulus, it is not reabsorbed here.
- **Option B:** The **loop of Henle** primarily handles water and electrolyte balance, not glucose reabsorption. Some glucose reabsorption may occur here but to a much lesser extent compared to the PCT.
- **Option D:** The **distal convoluted tubule (DCT)** and collecting ducts are primarily involved in electrolyte and water balance under the influence of hormones like aldosterone and ADH, not glucose reabsorption.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that the **threshold for glucose reabsorption** in the PCT is about 180 mg/dL. When blood glucose levels exceed this threshold, glucose appears in the urine (glycosuria). This concept is crucial in understanding diabetes mellitus and its diagnosis.

## **Correct Answer:** C. Proximal convoluted tubule.