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Blood donation and iron – what donors should know

10/22/2018 11:00

In recent months, iron deficiency, and ferritin in particular, has been discussed widely on various forums. Every time you give blood, your haemoglobin and iron levels fall temporarily. It is well known that those who give blood frequently and women of childbearing age are at risk of iron deficiency. This is why the Blood Service provides iron supplements to those at risk, in order to replace the iron lost in the donation. The minimum period between donations is also different for men and women.

Haemoglobin is the element in red blood cells that carries oxygen from the lungs to other parts of the body. Haemoglobin’s ability to carry oxygen is based on the iron it contains. Each person has an individual haemoglobin level.

On average, blood donation reduces the haemoglobin level by 10-15 units, and it also takes its toll on the iron resources. If the haemoglobin level falls below the reference values, 117 g/l for women and 134 g/l for men, we talk about anaemia. For blood donors, the haemoglobin limits are higher than the reference values; at least 125 g/l for women and 135 g/l for men. This is to ensure that the haemoglobin levels will not fall very low even temporarily. In 2017, of women offering to donate blood, 5.4% had a haemoglobin level below the limit. The figure for men was 2.1%.

We talk about anaemia when the haemoglobin level falls below the reference value. Anaemia is an illness, most commonly caused by an iron deficiency. It means that the body has insufficient iron stores, and the body is unable to produce sufficient levels of haemoglobin. Sometimes the iron stores may be low even before the person develops anaemia. Moderate iron deficiency that is not severe enough to cause the haemoglobin level to drop, may cause symptoms such as tiredness and lowered performance. An iron deficiency may also reduce the body’s resistance to infections.

One indicator of iron stores is ferritin, measured from a venous blood sample, but it is only one factor among a number of variables that affect the body’s iron balance. We still do not know all the details of the human iron metabolism and the mechanisms that regulate it.

An extensive iron and health study using Finnish data

The Blood Service is currently conducting scientific research on the effect of blood donation on the iron balance and health of donors. The Finnish research data of the FIN Donor 10 000 study is used to determine the best tests and measures for taking care of the donors’ health.

“There are many different models for blood donation around the world, and one model is not necessary suitable for every location,” says Johanna Castrén, chief medical officer at the Blood Service.

In connection with the FIN Donor 10 000 health study, the Blood Service has tested the donors’ ferritin and transferrin levels, but the ferritin levels have never been routinely tested in Finland in connection with blood donation. There are many reasons for this.

“Ferritin levels are not included in the requirements that regulate blood donation, while there are clear requirements regarding donors’ haemoglobin levels. International and national debates regarding the optimal ferritin levels and reference values are ongoing, and there is no real consensus on the topic. In addition, no definite indicators or tests have been determined globally for testing the iron balance for the purpose of blood donation,” Castrén continues.

Also, point-of-care testing of ferritin is not possible. This means that it is not possible to conduct the test and have the result before the person donates blood, as it is with haemoglobin.

The iron supplements are worth taking

Iron is a building block of the body. It is needed for haemoglobin in red cells, but also in muscles and the enzymes that regulate bodily functions. Iron is stored in bone marrow and the liver. There is great variation between people in their iron stores. In general, a man’s iron store is three times that of a woman’s.

In a healthy person, the iron lost at blood donation is replaced at an individual pace. The minimum period between blood donations is 61 days for men and 91 days for women. Previous studies have shown that, on average, a well-balanced diet will include enough iron to replace the iron lost at blood donation in around five months. However, the process is highly individual, and the time depends on other factors that affect the iron balance, such as menstruation with women. If you donate blood frequently, your body may not be able to replace lost iron with the iron contained in food.

“This phenomenon has been observed in the case of women of childbearing age, in particular. Therefore, we recommend that women below the age of 50 only donate blood once or twice a year,” Castrén says.

Good sources of iron include blood, liver and meat dishes. Good sources of iron for vegetarians include lentils, beans, soy, seaweed and wheat and rye bran. However, for vegetarians and those on special diets, food may not contain sufficient amounts of iron. In order to enhance your body’s absorption of iron, you can add products that are rich in vitamin C in your diet, such as citrus fruit and juice. Absorption of iron is enhanced if you suffer from iron deficiency.

In addition to donation intervals, measures are taken to counter the risk of iron deficiency caused by blood donations by providing donors in risk groups with iron supplements.

“We offer iron supplements to women below the age of 50 and to donors that last donated blood less than four months ago, regardless of their gender. You should always take the supplements, regardless of your haemoglobin levels, as the iron will replace the iron you lost at blood donation. If you are on medication, do not take the iron supplement at the same time as the medication, as iron affects the absorption of many medicines,” says Castrén.

The iron contained in food will not stop the absorption of the iron supplements, so donors should also eat foods that are rich in iron.

More results of the iron study will follow

The FIN Donor 10 000 iron study commenced in 2015. The first results published in conference presentations indicate that around one in ten people (11%) offering to donate blood suffer from iron deficiency. In the study, the limit for iron deficiency was the value used in other European studies on blood donors (15 ug/l ). Based on the health and lifestyle survey conducted on the participants, these people feel as healthy as the other blood donors, and they do not feel more tired during the day.

“We know that iron deficiency as such is very common, and further research is required on its significance to blood donors that feel healthy,” says Castrén.

Analysis of the results of the FIN Donor study continues, and later in the year, we can expect to see more scientific articles published on the topic. Donor well-being is vitally important to the Blood Service.

“At the Blood Service, our way of working is to study topics and use the information and evidence to develop blood donation. At the moment, we are researching more efficient and targeted ways of predicting and preventing the risk of iron deficiency among blood donors. In Finland, people have been donating blood for 70 years to help patients and, in terms of the nationwide blood supply chain, it is important to maintain this level of voluntary assistance while continuing to respect the donors and their health.​"