All are features of haemolytic uremic syndrome, except:
## **Core Concept**
Haemolytic uremic syndrome (HUS) is a complex condition characterized by the triad of **microangiopathic hemolytic anemia**, **acute kidney injury (uremia)**, and **thrombocytopenia**. It often presents as a complication of certain bacterial infections, most notably those caused by E. coli O157:H7.
## **Why the Correct Answer is Right**
The correct answer, option , showcases a feature not typically associated with HUS. HUS is primarily known for its effects on the kidneys, blood cells, and platelets. The condition leads to the formation of **blood clots in small blood vessels** throughout the body, which consumes platelets and leads to thrombocytopenia. The kidney damage results from the occlusion of small renal vessels and direct toxin-mediated injury.
## **Why Each Wrong Option is Incorrect**
- **Option A:** This option describes a condition that could plausibly be related to HUS, given its effects on the body, particularly if it mentions microangiopathic hemolytic anemia, acute kidney injury, or thrombocytopenia.
- **Option B:** Similarly, this option likely represents a feature seen in HUS, such as schistocytes on a blood smear (indicative of microangiopathic hemolytic anemia), elevated creatinine levels (indicative of acute kidney injury), or low platelet count.
- **Option C:** This option might describe another manifestation of HUS, such as hypertension or fluid overload, secondary to acute kidney injury.
## **Clinical Pearl / High-Yield Fact**
A key clinical pearl for HUS is that it often follows an **infection with Shiga toxin-producing E. coli (STEC)**, particularly in children. Early recognition and supportive care are critical. Laboratory findings typically include **schistocytes** (fragmented red blood cells), **thrombocytopenia**, and **elevated serum creatinine** levels.
## **Correct Answer: D. Coomb’s positive hemolytic anemia.**
This option stands out because HUS is characterized by a **Coombs-negative** (or non-immune) hemolytic anemia. The hemolysis in HUS is due to mechanical damage to red blood cells as they pass through small blood vessels partially occluded by fibrin clots, not due to an immune-mediated process.