Red cells incubated for several days in standard anticoagulant storage medium lose the ability to modulate hemoglobin oxygen affinity normally. Which metabolite declines during storage, and what is its effect if not restored before transfusion?

• A 2,3-BPG declines, causing a leftward shift and reduced tissue oxygen delivery ✓
• B ATP declines, causing a rightward shift of the oxygen dissociation curve
• C NADPH declines, causing methemoglobinemia and a rightward shift
• D Glucose-6-phosphate declines, causing a leftward shift and hemolysis

Explanation

The Rapoport-Luebering cycle diverts 1,3-BPG to 2,3-BPG via bisphosphoglycerate mutase, bypassing ATP generation. 2,3-BPG binds deoxyhemoglobin and stabilizes the T state, shifting the dissociation curve right. Stored red cells exhaust glycolysis, so 2,3-BPG falls over weeks, shifting the curve left and impairing oxygen unloading until regenerated after transfusion. ATP also falls during storage, but ATP does not bind hemoglobin to set oxygen affinity, so option B misstates the mechanism.

Reference: Lehninger Principles of Biochemistry, 8th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.