A 17-year-old patient is referred by his GP after presenting with periorbital oedema. The patient noticed the oedematous eyes 3 days ago, but repos feeling unwell since a throat infection 3 weeks ago with nausea and vomiting in the last week. A urine dipstick is positive for protein and blood while serum creatinine and urea are mildly deranged. The most likely diagnosis is:

**Core Concept**
Post-streptococcal glomerulonephritis (PSGN) is an immune-complex mediated form of glomerulonephritis that occurs following an infection with certain strains of streptococci, typically after a throat infection. The immune response to the bacterial infection leads to the formation of circulating immune complexes, which deposit in the glomeruli, causing inflammation and damage.

**Why the Correct Answer is Right**
The patient's recent history of a throat infection and the presence of periorbital edema, proteinuria, and hematuria are classic signs of PSGN. The mild derangement in serum creatinine and urea is consistent with the acute kidney injury seen in PSGN. The immune complexes deposited in the glomeruli activate the complement system, leading to the release of pro-inflammatory cytokines and the recruitment of neutrophils, which causes the characteristic glomerular injury.

**Why Each Wrong Option is Incorrect**
* **Option A:** Acute nephritic syndrome is a broader term that encompasses PSGN, but it is not specific enough to be the correct answer, as it can also be caused by other conditions such as lupus nephritis or IgA nephropathy.
* **Option B:** Goodpasture's syndrome is a rare autoimmune disease characterized by the presence of anti-GBM antibodies, which cause glomerulonephritis and pulmonary hemorrhage. However, it is not typically associated with a recent throat infection.
* **Option C:** Minimal change disease is a common cause of nephrotic syndrome in children, but it is not typically associated with hematuria or periorbital edema.

**Clinical Pearl / High-Yield Fact**
PSGN can occur 1-3 weeks after a throat infection, and the presence of periorbital edema is a classic sign of this condition. Remember the "Rapidly progressive glomerulonephritis" mnemonic to associate PSGN with the following symptoms: R - Recent streptococcal infection, A - Acute kidney injury, P - Periorbital edema, I - Immune complex deposition, D - Deterioration of renal function.

**Correct Answer:** C.

✓ Correct Answer: C. Post streptococcal GN