Thrombocytopenia is caused by:a) Heparinb) Acyclovirc) DICd) Henoch-schonlein purpura (HSP)e) Hemolytic uremic syndrome (HUS)
**Core Concept**
Thrombocytopenia refers to a decrease in platelet count, which can be caused by various factors including drug-induced platelet destruction, bone marrow failure, or increased platelet consumption. Understanding the pathophysiology behind each option is crucial to identifying the correct cause of thrombocytopenia.
**Why the Correct Answer is Right**
Option C, Disseminated Intravascular Coagulation (DIC), is a condition characterized by both widespread clotting and bleeding in the vascular system. It leads to platelet consumption, resulting in thrombocytopenia. In DIC, the body's clotting mechanism is activated, consuming platelets and clotting factors, ultimately causing a deficiency in these essential components. This process is mediated by the release of tissue factor, which triggers the coagulation cascade.
**Why Each Wrong Option is Incorrect**
**Option A:** Heparin-induced thrombocytopenia (HIT) is a distinct condition that occurs in response to heparin exposure. It is characterized by the formation of antibodies against the heparin-platelet factor 4 complex, leading to platelet activation and thrombosis, rather than thrombocytopenia.
**Option B:** Acyclovir, an antiviral medication, can cause renal failure and hemolytic uremic syndrome (HUS) as a rare side effect. However, it is not a direct cause of thrombocytopenia.
**Option D:** Henoch-Schönlein purpura (HSP) is a form of vasculitis that affects small blood vessels, leading to the deposition of immune complexes and inflammation. While HSP can cause purpura, it is not typically associated with thrombocytopenia.
**Option E:** Hemolytic uremic syndrome (HUS) is a condition characterized by hemolytic anemia, acute kidney injury, and thrombocytopenia. However, it is not the primary cause of thrombocytopenia in this context.
**Clinical Pearl / High-Yield Fact**
When evaluating a patient with thrombocytopenia, it is essential to consider the underlying cause, which can range from drug-induced effects to underlying bone marrow disorders. A careful history, physical examination, and laboratory investigations can help differentiate between these causes.
**Correct Answer:** C. Disseminated Intravascular Coagulation (DIC)