Rapid replacement: 465 milliliters of whole blood are taken from a blood donation: “The body – it consists of 70 percent water – reacts immediately and releases fluid into the circulatory system, within around 24 hours the blood volume is replenished,” says the doctor Ursula Kreil, head the collection in the blood donation center of the Red Cross for Vienna, Lower Austria, Burgenland. “The blood platelets and white blood cells are also replenished within a few hours from the available stores.” The formation of new red blood cells takes the longest, at least a week. “The fact that the minimum interval between two whole blood donations is eight weeks is simply due to the extremely high protection criteria for the donors.” Women are allowed to donate four to five times a year, men up to six times.
Hemoglobin measurement: Before each blood donation, the level of hemoglobin, the red blood pigment, is measured. This consists largely of iron and gives the blood its red color. “For a donation, the lower hemoglobin limit must be reached or exceeded,” emphasizes Kreil. A lower value would be an indication of iron deficiency. The transport of oxygen and the formation of new red blood cells are then at risk. In such a case, further investigations by the family doctor always reveal previously unrecognized causes of iron deficiency: “It can be a very unbalanced diet as well as a small but chronic loss of blood through gastritis.”
blood pressure measurement: 180/100 mmHg is the upper blood pressure limit for blood donation. “This is usually much too high (high blood pressure is a permanent value above 140/90 mmHg), but sometimes our blood donors are also excited before donating,” says Kreil. “In the case of such values, we always advise to continue measuring and to have it clarified by the doctor. But we also discover values above 200 mmHg, we send these people to the family doctor or to an ambulance immediately.”
Infection Check: Blood donors also benefit from the testing for many infectious agents (HIV, various hepatitis viruses, ringworm, syphilis …) It is now extremely rare for an infection to go undetected: the statistically calculated risk for HIV is 1 in 4, 3 million, hepatitis C 1 in 10 million and hepatitis B 1 in 400,000. Kreil: “For comparison: In Austria, around 350,000 blood products are used every year.” The new corona virus is not transmitted through blood products: “There is no indication of that.”
Psyche: “To this day, there is no equivalent alternative as a substitute for donated blood,” says Kreil: “This good feeling of having helped other people with your blood donation does not wear off, even with long-term donors. This is very valuable for mental health.”