The Question is from neet-zoology body-fluids-and-circulation coagulation-of-blood, and it was created by the author Mr. BALACHANDRA.N

Question

A patient presents with a rare bleeding disorder characterized by a prolonged bleeding time but normal platelet count and PT/INR.  Further investigation reveals a deficiency in a specific plasma protein crucial for platelet adhesion. Which of the following factors is MOST likely deficient?

Mr. BALACHANDRA.N · Accepted Answer

## CORE INFORMATION
✓ **Answer**: A
## CONCEPT FRAMEWORK
 **Primary Concept**: Hemostasis and coagulation cascade
 **Related Topics**: Platelet function, bleeding disorders, von Willebrand disease
 **Prerequisites**: Understanding of the role of platelets in primary hemostasis and the coagulation cascade.
## SOLUTION PATHWAY
**Given Information**:
  * Prolonged bleeding time
  * Normal platelet count
  * Normal PT/INR (Prothrombin Time/International Normalized Ratio)
  * Deficiency in a plasma protein crucial for platelet adhesion
**Method & Steps**:
 1. Analyze the given information.  The prolonged bleeding time indicates a problem with primary hemostasis (the initial phase of blood clotting involving platelets).  Normal platelet count rules out thrombocytopenia (low platelet count). Normal PT/INR indicates that the coagulation cascade (secondary hemostasis) is functioning correctly.
  Reasoning: The problem lies specifically in platelet adhesion, a critical step in primary hemostasis.
  Formula/Rule: None directly applicable, this is a qualitative diagnostic reasoning problem.
 2. Consider the role of von Willebrand factor (vWF). vWF is a plasma protein that acts as a bridge between platelets and the subendothelial collagen exposed at sites of vascular injury.  It facilitates platelet adhesion and aggregation.
  Working: A deficiency in vWF would lead to impaired platelet adhesion, resulting in prolonged bleeding time despite normal platelet count and coagulation factors.
  Key Point:  vWF is essential for platelet adhesion, a key step in primary hemostasis.
 3. Eliminate other options. Factor VIII, Factor IX, and Fibrinogen are all involved in the coagulation cascade (secondary hemostasis), which is functioning normally as indicated by the normal PT/INR.
  Result: von Willebrand factor (vWF) deficiency is the most likely diagnosis.
  Verification: The symptoms (prolonged bleeding time, normal platelet count, normal PT/INR) are consistent with von Willebrand disease.
 ## OPTION ANALYSIS
A ✓: von Willebrand factor (vWF) deficiency is the correct answer because vWF is crucial for platelet adhesion to the subendothelial collagen, which is the primary defect in this scenario.
B :x: Factor VIII deficiency causes hemophilia A, which affects the coagulation cascade (secondary hemostasis), not platelet adhesion.
 C :x: Factor IX deficiency causes hemophilia B, also affecting the coagulation cascade, not platelet adhesion.
D :x: Fibrinogen is crucial for the final step of coagulation, the formation of a stable fibrin clot.  A deficiency would affect secondary hemostasis, not primary hemostasis.
 ## LEARNING AIDS
 **Common Mistakes**:
  1.Confusing primary and secondary hemostasis:  Understanding the distinction between platelet function (primary) and coagulation factor function (secondary) is crucial.
   How to avoid:  Review the steps of hemostasis and the roles of different factors.
  2.Overlooking the significance of normal PT/INR:  The normal PT/INR helps to narrow down the possibilities.
   How to avoid:  Thoroughly analyze all given information.
 **Quick Tips**:
  1.Bleeding time is a key indicator of platelet function.
  2.Remember the role of vWF in platelet adhesion.

Mr. BALACHANDRA.N · Answer

The correct Option is "von Willebrand factor"

Mr. BALACHANDRA.N · Answer

Factor VIII

Mr. BALACHANDRA.N · Answer

Factor IX

Mr. BALACHANDRA.N · Answer

Fibrinogen

NEET Zoology Body Fluids And Circulation Coagulation Of Blood MCQs

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