What is the known change occurring in stored blood?

Changes in Stored Blood

The most significant known change occurring in stored blood is increased H+ (option A), which leads to acidification of the stored blood.

Biochemical Changes in Stored Blood

When blood is stored for transfusion purposes, several biochemical changes occur over time, collectively known as the "storage lesion." These changes affect the quality and functionality of the blood components, particularly red blood cells (RBCs).

Primary Changes in Stored Blood

1. Increased H+ (Acidification) 1

   • As blood is stored, glycolysis continues in RBCs, leading to lactic acid production
   • The pH of stored blood decreases progressively during storage
   • This acidification occurs because RBCs continue anaerobic metabolism, producing lactate and H+ ions

2. Decreased 2,3-DPG (not increased) 1

   • Contrary to option B, 2,3-diphosphoglycerate (2,3-DPG) actually decreases during storage
   • This reduction in 2,3-DPG affects oxygen delivery as it reduces the ability of hemoglobin to release oxygen to tissues
   • The guidelines specifically mention "reduction in 2,3-DPG" as part of the storage lesion

3. Increased (not decreased) Red Cell Fragility 1

   • RBCs become more fragile during storage, not less fragile as suggested in option C
   • There is "reduction in deformability" and "altered adhesiveness and aggregability"
   • These changes make stored RBCs more susceptible to hemolysis

4. Increased (not decreased) K+ 1

   • Potassium leaks from RBCs into the plasma during storage
   • This results in hyperkalemia in stored blood, not hypokalemia as suggested in option D
   • The loss of K+ from cells is due to progressive dysfunction of the Na+/K+ ATPase pump as ATP levels decline

Other Important Storage-Related Changes

• ATP depletion: Reduced energy availability for cellular functions 1
• Accumulation of bioactive compounds: These have proinflammatory effects 1
• Reduced post-transfusion viability: Due to the cumulative effects of the storage lesion 1

Clinical Implications

The acidification of stored blood has important clinical implications:

• May contribute to metabolic acidosis in massive transfusions
• Can affect coagulation pathways
• May impact oxygen delivery to tissues

Conclusion

Among the options provided, the correct answer is A. Increased H+. This acidification occurs due to ongoing glycolysis with lactate and H+ production during storage. Options B, C, and D are incorrect as they either state the opposite of what actually occurs (2,3-DPG decreases, red cell fragility increases, K+ increases) or are not supported by the evidence provided.