June 15, 2000 WT Questions from Readers page 31
The article names the primary components of blood as being 1) red cells; 2) white cells; 3) platelets; 4) plasma serum, the fluid part.
Blood can be processed beyond that point. Plasma (primary component 4) contains albumin, clotting factors, and antibodies. Clotting factor VIII (a blood fraction of the primary component 4) has been given to hemophiliacs.
Gamma globulin (a blood fraction of the primary component 4), extracted from people who already have immunity, can be injected into people who have been exposed to the same disease to prevent infection.
"The other primary components (red cells, white cells, platelets) can be processed into smaller parts."
Hemoglobin is a fraction, a smaller part of red blood cells. Hemopure and similar products are defined as hemoglobin-based.
In addressing the question of the blood being poured out the article says, "to prepare gamma globulin, blood-based clotting factors, and so on, requires that blood be collected and processed. Hence some Christians reject such products...their...conscientious stand should be respected. Other Christians decide differently..." then they refer the reader to the June 1, 1990, WT giving the example of the transfer of blood fractions between mother and child.
"Some Christians may conclude that since blood fractions can pass to another person in this natural setting (pregnant woman to her child), they could accept a blood fraction derived from blood plasma or cells."
So it is up to the individual Witness if they choose to be treated or not with "a blood fraction derived from blood plasma or cells."