**Core Concept**
Acute diffuse proliferative glomerulonephritis (ADPGN) is an immune complex-mediated inflammatory process involving the glomeruli, typically resulting from post-streptococcal glomerulonephritis (PSGN) or other causes of immune complex deposition. This condition leads to glomerular injury, characterized by the influx of inflammatory cells and the formation of immune complexes.

**Why the Correct Answer is Right**
The correct answer, **D. Hypoalbuminaemia**, is incorrect because ADPGN typically presents with nephrotic syndrome, characterized by massive proteinuria, leading to hypoalbuminemia. However, the hallmark of ADPGN is nephritic syndrome, characterized by hematuria, hypertension, and oliguria, rather than nephrotic syndrome. Nephritic syndrome is associated with the presence of hematuria and normal to low levels of proteinuria, not hypoalbuminemia.

**Why Each Wrong Option is Incorrect**
**Option A:** Microscopic haematuria is a characteristic feature of ADPGN, resulting from the inflammatory process and immune complex deposition within the glomeruli. This option is correct, not incorrect.
**Option B:** Raised blood urea level is a consequence of the decreased glomerular filtration rate (GFR) seen in ADPGN, making this option correct, not incorrect.
**Option C:** Raised serum creatinine level is also a consequence of the decreased GFR in ADPGN, making this option correct, not incorrect.

**Clinical Pearl / High-Yield Fact**
It's essential to differentiate between nephritic and nephrotic syndromes, as they have distinct pathophysiologies and clinical presentations. Nephritic syndrome is characterized by hematuria, hypertension, and normal to low levels of proteinuria, whereas nephrotic syndrome is characterized by massive proteinuria, hypoalbuminemia, and edema.

**Correct Answer Line**
✓ Correct Answer: D. Hypoalbuminaemia