Hemolytic Uremic Syndrome is characterizeda) Microangiopathic haemolytic anaemiab) ↓ed LDHc) Thrombocytopaeniad) Renal failuree) Positive Coomb’s test
**Core Concept**
Hemolytic Uremic Syndrome (HUS) is a complex condition characterized by the triad of **microangiopathic hemolytic anemia**, **thrombocytopenia**, and **renal failure**. It is often associated with **Shiga toxin-producing Escherichia coli** infections. The underlying mechanism involves endothelial cell injury and activation, leading to a prothrombotic state.
**Why the Correct Answer is Right**
The correct answer includes **microangiopathic hemolytic anemia**, which is a hallmark of HUS, resulting from the mechanical damage to red blood cells as they pass through the small blood vessels filled with fibrin clots. **Thrombocytopenia** occurs due to the consumption of platelets in the formation of these clots. **Renal failure** is a consequence of the obstruction of small renal vessels by fibrin clots, leading to acute kidney injury.
**Why Each Wrong Option is Incorrect**
**Option B:** Decreased LDH is incorrect because LDH levels are typically elevated in HUS due to hemolysis.
**Option E:** A positive Coomb's test is incorrect because it indicates an immune-mediated hemolytic anemia, which is not characteristic of HUS.
**Clinical Pearl / High-Yield Fact**
A key point to remember is that HUS is distinguished from Thrombotic Thrombocytopenic Purpura (TTP) by the presence of significant renal failure and the absence of neurological symptoms.
**Correct Answer:** D. a, c, d. microangiopathic haemolytic anaemia, thrombocytopaenia, renal failure