A trauma patient receives 14 units of packed red blood cells over three hours during massive transfusion. He develops perioral tingling, prolonged QT interval on ECG, and tetany despite adequate resuscitation. Which biochemical abnormality is responsible?

• A Low ionised calcium from citrate chelation ✓
• B Hyperkalaemia
• C Hypermagnesaemia
• D Metabolic alkalosis with respiratory compensation

Explanation

Citrate anticoagulant in stored blood chelates ionised calcium. In massive transfusion the liver may not metabolise the citrate load fast enough, producing symptomatic hypocalcaemia with perioral numbness, tetany, and QT prolongation. Treatment is intravenous calcium gluconate. Total serum calcium may appear normal because the bound fraction rises, so ionised calcium is the value to follow. Hypertonic citrate also causes acidosis initially, not alkalosis.

Reference: Bailey and Love's Short Practice of Surgery, 27th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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