Evaluate magnesium stores
2 mL Plasma
2 mL Packed RBCs
0.5 mL Plasma
0.5 mL Packed RBCs
Collect whole blood in a Metal-free Royal Blue Top Tube with EDTA (RBTT).
Both packed red blood cells and plasma are required. Spin down and separate plasma and red blood cells immediately. Transfer 2 mL plasma and 2 mL packed red blood cells into separate metal-free tubes. Failure to separate plasma from cells may cause rejection due to hemolysis of red cells and contamination of the plasma. Specimen must be received at Medtox within 5 days of collection.
NOTE: Both plasma and packed red blood cells are required for testing.