From the Guidelines
Patients develop hypocalcemia after blood transfusion because the citrate used as a preservative and anticoagulant in blood products binds to ionized calcium, leading to a decrease in its concentration 1.
Causes of Hypocalcemia
- Citrate-mediated chelation of serum Ca2+: Each unit of pRBC or FFP contains approximately 3 g of citrate, which is normally metabolized by the liver, but in cases of massive transfusion, liver function may be impaired due to hypoperfusion, leading to citrate accumulation and subsequent hypocalcemia 1.
- Impaired liver function: Hypoperfusion, hypothermia, and hepatic insufficiency can dramatically impair citrate metabolism, contributing to hypocalcemia 1.
Clinical Significance
- Coagulopathy: Hypocalcemia can impair the coagulation cascade, as ionized calcium is essential for the activation of factors II, VII, IX, and X, as well as proteins C and S 1.
- Cardiac contractility: Reduced ionized calcium levels can compromise cardiac contractility and systemic vascular resistance 1.
Management
- Monitoring: Ionized calcium levels should be monitored during massive transfusion, and calcium chloride should be administered to correct hypocalcemia 1.
- Calcium supplementation: Calcium chloride is the preferred agent for correcting hypocalcemia, as it contains more elemental calcium than calcium gluconate and may be preferable in cases of abnormal liver function 1.
From the Research
Causes of Hypocalcemia after Blood Transfusion
- Hypocalcemia is a common condition that can occur after blood transfusion, particularly in patients who receive massive transfusions 2, 3, 4, 5.
- The primary cause of hypocalcemia after blood transfusion is the chelation of calcium by citrate, a preservative found in blood products 2, 4, 5.
- Citrate can bind to calcium, leading to a decrease in ionized calcium levels, which can cause hypocalcemia 2, 4.
Risk Factors for Hypocalcemia after Blood Transfusion
- Patients who receive massive transfusions are at a higher risk of developing hypocalcemia 4, 5.
- The risk of hypocalcemia increases with the amount of blood products transfused 2, 4, 5.
- Patients with liver dysfunction may be at a higher risk of developing hypocalcemia after blood transfusion due to impaired calcium metabolism 3.
Clinical Implications of Hypocalcemia after Blood Transfusion
- Hypocalcemia can lead to cardiovascular instability, coagulopathy, and increased mortality 2, 3, 4.
- Prompt recognition and treatment of hypocalcemia are essential to prevent these complications 2, 4.
- Calcium supplementation may be necessary to correct hypocalcemia, particularly in patients who receive massive transfusions 4, 5.