Cr-51 Labeled RBCs

• Uses

  • RBC Mass

  • RBC Survival and Sequestration

• Properties of Cr-51

  • Half-life = 28 days

  • Gamma energy = 320 keV

Principle of Labeling Cr-51RBCs

• Cr-51 in the form of Na₂CrO₄ (6⁺ oxidation state) is incubated with RBCs

  • Cr-51 binds to RBCs  

  • Reaction terminated by adding a reducing agent such as ascorbic acid  

Procedure for Labeling Cr-51 RBCs

1.   Obtain 25-30 mL of anticoagulated blood

2.   Combine blood with 75 - 150 µCi Cr-51

3.   Incubate 20-30 minutes at 37ºC or at room temp

4.  Add 100 mg ascorbic acid and incubate 5 more minutes

5.   Remove and use the labeled cells