When labeling RBC with Cr-51 Sodium Chromate, what component is added to the ACD solution first?

When labeling red blood cells (RBCs) with Chromium-51 (Cr-51) Sodium Chromate, the blood sample is added to the anticoagulant solution known as ACD (Acid-Citrate-Dextrose) first. This process involves several steps to ensure effective labeling of the RBCs.

By placing the blood sample into the ACD solution first, the anticoagulant begins to work immediately to prevent coagulation. This is crucial because the goal is to keep the RBCs in a liquid state for the labeling procedure. The ACD solution preserves the integrity of the red blood cells while they are being labeled, which is essential for accurate nuclear imaging results later on.

The subsequent addition of Cr-51 Sodium Chromate occurs after the blood sample has been adequately mixed with the ACD solution. This sequence is significant because it allows the labeling process to occur effectively without prematurely triggering clotting, which would hinder the process and affect the quality of trace results.

In summary, the rationale for adding the blood sample first is rooted in maintaining the viability of the RBCs and ensuring that the anticoagulant can perform its function before introducing the radioactive label.