**Question:** All of the following are adverse effects of unfractionated heparin except:-

A. Bleeding
B. Inhibition of platelet aggregation
C. Increased urine output
D. Anticoagulation

**Core Concept:** Unfractionated heparin is an anticoagulant drug used to prevent and treat thrombosis, but it can cause a range of adverse effects.

**Why the Correct Answer is Right:**

C. Increased urine output is not an adverse effect of unfractionated heparin. Instead, it is a beneficial effect known as heparin-induced thrombocytopenia (HIT), which occurs in a small proportion of patients on unfractionated heparin therapy.

D. Anticoagulation is a correct description of the primary action of unfractionated heparin, but it does not specifically address adverse effects.

**Why Each Wrong Option is Incorrect:**

A. Heparin can cause bleeding as a side effect due to its potent anticoagulant action on platelets and coagulation factors.

B. Heparin does not inhibit platelet aggregation; instead, it enhances platelet function by activating glycoprotein IIb/IIIa receptor, which promotes platelet aggregation and reduces bleeding tendency.

**Clinical Pearl / High-Yield Fact:**

Heparin-induced thrombocytopenia (HIT) is a potentially severe complication of heparin therapy that occurs in 1-5% of patients. It is an immune-mediated response to heparin and results in a significant decrease in platelet count and increased risk of thrombosis.

**Correct Answer:** C. Increased urine output (heparin-induced thrombocytopenia) is not an adverse effect of unfractionated heparin.