A 10 year old child develops hematuria after 2 days of diarrhoea. Blood film shows fragmented RBCs & thrombocytopenia. Ultrasound shows marked enlargement of both kidneys. The likely diagnosis is –
**Core Concept**
Hemolytic uremic syndrome (HUS) is a disorder characterized by the triad of microangiopathic hemolytic anemia, thrombocytopenia, and acute kidney injury, often preceded by a diarrheal illness caused by Shiga toxin-producing Escherichia coli (E. coli).
**Why the Correct Answer is Right**
The child's presentation of hematuria, fragmented red blood cells, thrombocytopenia, and marked kidney enlargement is consistent with HUS. Shiga toxin produced by E. coli bacteria during the diarrheal illness causes endothelial damage, leading to microangiopathic hemolytic anemia and thrombocytopenia. The kidneys become enlarged due to acute kidney injury and subsequent inflammation. The blood film shows fragmented red blood cells due to mechanical damage as they pass through the narrowed blood vessels.
**Why Each Wrong Option is Incorrect**
* **Option A:** While IgA nephropathy can cause hematuria, it does not typically present with the triad of microangiopathic hemolytic anemia, thrombocytopenia, and acute kidney injury seen in HUS.
* **Option B:** Post-streptococcal glomerulonephritis (PSGN) can cause hematuria and acute kidney injury, but it does not typically present with thrombocytopenia or fragmented red blood cells.
* **Option C:** Goodpasture syndrome is an autoimmune disease that causes pulmonary hemorrhage and glomerulonephritis, but it does not typically present with the triad of microangiopathic hemolytic anemia, thrombocytopenia, and acute kidney injury seen in HUS.
**Clinical Pearl / High-Yield Fact**
HUS is a medical emergency that often requires supportive care, including dialysis and transfusions, and close monitoring for complications such as acute kidney injury and thrombotic thrombocytopenic purpura (TTP).
**Correct Answer: C. HUS**