A 12 year old boy had severe vomiting and diarrhoea. He was brought to the hospital bacause of severe oliguria. He was given IV fluids and furosemide without any diuresis. Blood beichemistry revealed : Urea 120 mg% and serum creatinine 4 mg%. The most likely diagnosis is –

**Core Concept**
In this scenario, the patient is presenting with severe oliguria (decreased urine output), which is a sign of acute kidney injury (AKI). The patient's blood biochemistry results show elevated urea and serum creatinine levels, further supporting the diagnosis of AKI.

**Why the Correct Answer is Right**
The patient's failure to respond to IV fluids and furosemide suggests that the cause of AKI is not related to volume depletion or pre-renal causes, which are typically responsive to fluid resuscitation and diuretics. The presence of severe vomiting and diarrhea may have contributed to volume depletion, but the lack of response to furosemide indicates that the kidneys are not functioning properly. This is suggestive of intrinsic renal damage, which may be due to a variety of causes including ischemia, toxins, or medications.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is not provided, so we cannot evaluate it.
* **Option B:** This option is also not provided, so we cannot evaluate it.
* **Option C:** This option is not provided, so we cannot evaluate it.
* **Option D:** This option is not provided, so we cannot evaluate it.

**Clinical Pearl / High-Yield Fact**
In patients with AKI, the absence of response to furosemide (a loop diuretic) is a critical clue to differentiate between pre-renal and intrinsic causes of AKI. This is because furosemide is often effective in patients with pre-renal AKI, but not in those with intrinsic AKI.

**Correct Answer:** Not enough options to determine, however, the likely diagnosis could be acute tubular necrosis (ATN) or another intrinsic renal cause of AKI.

✓ Correct Answer: B. Haemolytic uraemic syndrome