Haemophilia occurs due to deficiency of clotting factor?

Appeared in: NHM UP Staff Nurse - 2016

Explanation

Haemophilia is a group of inherited bleeding disorders caused by a deficiency in a clotting factor.
The most common type is Haemophilia A, which accounts for approximately 80% of cases.
Haemophilia A is specifically caused by a deficiency or reduced activity of clotting Factor VIII.
Because it is the most prevalent form, a general question about 'haemophilia' most often refers to Factor VIII deficiency.

Option A: Factor VI is an obsolete term in the coagulation cascade and is not a recognized clotting factor deficiency.
Option B: Deficiency of Factor VII is a distinct bleeding disorder that affects the extrinsic pathway of coagulation, leading to a prolonged Prothrombin Time (PT). Haemophilia affects the intrinsic pathway (prolonged aPTT).
Option D: Deficiency of Factor IX causes Haemophilia B (also known as Christmas disease). While this is a type of haemophilia, it is significantly less common than Haemophilia A (Factor VIII deficiency).

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Pathophysiology of Haemophilia and Clotting Factors as background academic context rather than a clinical decision trigger.
Nurses must be aware of the specific factor deficiency to administer the correct replacement therapy (Factor VIII for Haemophilia A, Factor IX for Haemophilia B).
Patient education is a key nursing role, including teaching bleeding precautions (e.g., using soft-bristled toothbrushes, avoiding contact sports), signs of internal bleeding, and how to manage minor bleeds at home.
A critical nursing intervention is to avoid intramuscular (IM) injections, aspirin, and other NSAIDs in patients with haemophilia, as these can provoke or worsen bleeding.

How to Approach the Question

First, identify the core concept of the question, which is the cause of haemophilia.
Recall that haemophilia is an inherited bleeding disorder related to clotting factor deficiencies.
Differentiate between the two main types: Haemophilia A and Haemophilia B.
Remember that Haemophilia A is caused by Factor VIII deficiency and is the most common type.
Remember that Haemophilia B is caused by Factor IX deficiency and is less common.
Since the question asks about 'haemophilia' in general, select the factor associated with the most common form, which is Factor VIII.

Concept Tested & Keywords

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E6 Medicine Davidson Principles Practice 24e p. 991-993

E6 PATHOLOGY QUICK REVIEWBased on Harsh Mohan Textbook of PATHOLOGY p. 134-136

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