Which is the substance which played an important role in blood coagulation?

SGPGI Nursing Officer-2022

Applied Physiology

Easy

Appeared in: SGPGI Nursing Officer-2022

Explanation

Calcium (Ca²⁺), designated as Factor IV, is an essential ion required for blood clotting.
It acts as a critical cofactor in multiple steps of the coagulation cascade, both intrinsic and extrinsic pathways.
Specifically, it is required for the activation of Factor X and the conversion of prothrombin to thrombin.
Without sufficient calcium, the coagulation process is severely impaired.

Option A: Sodium (Na) is a key electrolyte for maintaining fluid balance, blood pressure, and nerve function, but it does not act as a direct cofactor in the enzymatic reactions of the coagulation cascade.
Option B: Potassium (K) is the main intracellular electrolyte, crucial for nerve impulse transmission and muscle contraction, especially cardiac muscle. It is not a clotting factor.
Option D: Magnesium sulfate (MgSO₄) is not a procoagulant. In high concentrations, magnesium can actually inhibit coagulation by interfering with platelet function and acting as a calcium antagonist.

Clinical Relevance

Nursing practice connection: Knowing Role of electrolytes in blood coagulation helps nurses interpret findings accurately and avoid errors in routine assessment, medication administration, and patient teaching.
Nurses must understand that anticoagulants in blood collection tubes, such as EDTA (lavender top) and Sodium Citrate (light blue top), work by binding (chelating) calcium to prevent the sample from clotting.
This principle is why citrated solutions (like CPD) are used to store blood for transfusions; they prevent the blood from clotting in the bag by making calcium unavailable.
What if? If a patient has severe hypocalcemia (low blood calcium), their clotting time can be prolonged, increasing their risk of bleeding. This is a critical consideration in patients receiving massive blood transfusions (as citrate in transfused blood can bind to the patient's own calcium) or those with certain endocrine disorders.

How to Approach the Question

First, identify the core physiological process asked in the question, which is 'blood coagulation'.
Review the options provided: Sodium (Na), Potassium (K), Calcium (Ca), and Magnesium sulfate (MgSO4). These are all electrolytes or ionic compounds.
Recall the key components of the coagulation cascade. This process involves a series of proteins called clotting factors (numbered I to XIII) and essential cofactors.
Remember that one of these numbered factors is not a protein but an ion.
Identify that Calcium (Ca²⁺) is designated as Factor IV and is indispensable for several enzymatic steps in the cascade, making it the correct answer.

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