A 10 years boy presented with Cola coloured urine, oliguria for 3 days, facial puffiness, edema and hypeension. Urine albumin is positive and C3 levels are reduced. BP is 130/80. He had skin infection two weeks back. Which of the following is true about this condition?

## **Core Concept**
The patient's presentation suggests a diagnosis of **Post-Streptococcal Glomerulonephritis (PSGN)**, a type of immune-mediated glomerulonephritis that occurs following a streptococcal infection, such as skin infection (impetigo) or pharyngitis. PSGN is characterized by the deposition of immune complexes in the glomeruli, leading to complement activation and inflammation.

## **Why the Correct Answer is Right**
The key features of PSGN include:
- **Short latency period**: Typically 1-3 weeks after a streptococcal infection.
- **Hematuria**: Often presenting with cola-colored urine due to the presence of blood.
- **Proteinuria**: Can range from mild to nephrotic levels.
- **Oliguria**: Reduced urine output.
- **Hypertension**: Due to fluid retention and renal impairment.
- **Low C3 levels**: Complement level 3 (C3) is usually decreased during the acute phase due to immune complex deposition and consumption.

## **Why Each Wrong Option is Incorrect**
- **Option A:** Not provided, thus cannot be evaluated.
- **Option B:** Not provided, thus cannot be evaluated.
- **Option C:** Not provided, thus cannot be evaluated.

## **Clinical Pearl / High-Yield Fact**
A crucial point to remember is that **C3 levels return to normal within 8-12 weeks** in PSGN, which helps differentiate it from other causes of glomerulonephritis that may present with persistently low C3 levels, such as membranoproliferative glomerulonephritis.

## **Correct Answer:** D.

✓ Correct Answer: B. C3 levels return to normal in 6-8 weeks