Why does the Blood Service measure donors’ haemoglobin levels but not the iron reserves, such as ferritin?

Measuring the haemoglobin levels of potential blood donors is a regulatory requirement. The measurement ensures that the donor does not have anaemia, or in other words that their haemoglobin concentration is not too low. People can donate blood if their blood haemoglobin concentration is 125–175 g/l for women and 135–195 g/l for men. Donating blood lowers the haemoglobin concentration temporarily by 10–15 g/l.

Blood donors lose iron while donating blood. Iron deficiency occurs most in the youngest female donors (18–25-year-olds). For this group, we recommend donating blood no more than once a year. For other women, we recommend a maximum of 2–3 donations a year and for men a maximum of 3–4 donations a year. Donation interval, rather than a factor such as the donor’s age or diet, is the strongest single indicator of iron levels.

The Blood Service does not have exact requirements or recommendations concerning ferritin levels for potential blood donors who have had their ferritin levels measured independently. In terms of blood donation, the interpretation of ferritin levels depends on why the ferritin levels and iron stores have been investigated. If the levels have been measured for diagnostic purposes and low ferritin levels have been measured, the individual in question may not donate blood. On the other hand, an incidental finding of low ferritin levels in an asymptomatic person is not, in itself, an obstacle to donation. At the Blood Service, the prevention of harmful iron deficiency is based on the different recommended donation intervals for women and men (see above) and the minimum donation intervals (at least 91 days for women and at least 61 days for men), as well as on the administration of iron supplements to blood donors in the risk group (women under the age of 50 as well as all frequent donors).

Blood donors must feel well; you may not donate blood if you feel exhausted or exceptionally tired. Diagnosed iron deficiency anaemia or other symptomatic condition associated with iron deficiency should be treated. You may donate blood when your condition has improved and you have been treated for iron deficiency at least for six months.