What is hemoglobin?
Hemoglobin is the pigment that makes blood red. It is essential to transport oxygen from our lungs to the cells in our body. The hemoglobin molecule contains iron, an essential mineral found in our diet.
What are normal hemoglobin levels?
Normal hemoglobin levels are different in women and in men. In non-pregnant women, normal hemoglobin ranges from 120 g/L to 160 g/L (12.0 g/dL to 16.0 g/dL). In men, normal hemoglobin levels range from 140 g/L to 180 g/L (14.0 g/dL to 18.0 g/dL).
How is hemoglobin measured?
At a blood donor clinic, hemoglobin is checked before every donation. A sterile, single use device (lancet) is used to obtain a drop of blood from your finger. The blood sample is tested on a machine that determines the hemoglobin level. The screening method used in the blood donation setting is not as precise as testing performed on a venous blood sample analysed in a laboratory.
For donors who are donating platelets by apheresis, a sample is taken from the first few millilitres of blood in the collection bag, and analysed on a machine to determine hemoglobin. For donors who are donating plasma by apheresis, a finger stick sample is taken to measure hematocrit. Hematocrit is the percentage of the sample that consists of red cells, which contain the hemoglobin.
Why do we measure hemoglobin level?
Hemoglobin is measured mainly to protect blood donors. Hemoglobin level will temporarily drop after blood donation. If a donor has normal iron reserves and adequate iron in their diet, then new red blood cells will be made and hemoglobin levels will return to normal in less than 56 days. It is important not to donate blood if the hemoglobin level is already low. In addition, a check of donor hemoglobin is important to ensure the quality of the red blood cells that will be transfused.
What is the minimum hemoglobin level for whole blood donation?
The minimum hemoglobin level for whole blood donations for both men and women is 125 g/L (12.5 g/dL).
What if I don't meet minimum hemoglobin criteria?
Approximately 10% of female donors do not meet minimum hemoglobin criteria on a given donation. This is because women with low normal hemoglobin between 120 and 124 g/L (12.0 to 12.4 g/dL) will be deferred from donation. Many donors with borderline low hemoglobin will be eligible on their next attempt to donate. However, donors who do not meet minimum hemoglobin criteria may also have anemia. In women mild anemia is most often due to low iron reserves (see section on iron). Borderline anemia may indicate a lack of iron in your diet, combined with normal iron loss in menstrual periods and with pregnancies. Frequent blood donation contributes to iron loss and anemia.
Anemia may also indicate more serious medical problems. The problems may be related to poor absorption of iron from the diet, such as celiac disease. Alternatively, anemia may be due to increased blood loss, which may occur with stomach ulcers, polyps, or even cancer of the colon. Serious medical problems are more likely in individuals with lower hemoglobin levels. Particularly if your hemoglobin level is below 110 g/L (11.0 g/dL) you should see your physician to have further testing to confirm if anemia is present and determine the underlying cause. If anemia is present, you should not return to donate until the cause of the low hemoglobin has been identified and corrected.
It is quite rare for male donors to have a hemoglobin level below the minimum blood donor criteria. Male donors with a hemoglobin level below the acceptable level of 125 g/L (12.5 g/dL) are considered to be anemic. If your hemoglobin was below the acceptable level, further testing should be done by your physician to confirm if anemia is present and what is the underlying cause. Possible causes include difficulties absorbing iron from diet, such as celiac disease. Very frequent blood donation may contribute to iron loss and anemia. Other causes include increased blood loss, often in the gastro-intestinal tract, such as stomach ulcers, polyps, and even colon cancer. Blood loss may be very gradual and not noticeable on a daily basis. If you have been deferred for low hemoglobin, you should not return to donate until your physician has determined if anemia is actually present, and the cause of the low hemoglobin has been identified and corrected.
I am a healthy female donor, but seem to fail my fingerstick hemoglobin test every second time. What should I do?
If your physician has not found any medical problem, but you have borderline hemoglobin results and are often failing your fingerstick test, we recommend that you decrease the frequency of your donor clinic visits, in order to maintain better iron stores. For example, if you are trying to donate every 56 days and failing your fingerstick hemoglobin test every second time, we suggest that you attend a clinic every 6 months. In addition, you should try and increase your iron intake (see iron section). These 2 actions together should improve your ability to successfully donate.
Can blood donation cause anemia?
Whole blood donation results in a drop in hemoglobin of approximately 10 g/L (approximately 6-8%), depending on the size of the donor. Normal, healthy donors produce new red blood cells to replace those that were donated. However, iron is an essential mineral necessary to produce new red blood cells. Blood donation contributes to iron loss. It is therefore very important for blood donors to have an adequate amount of iron. This is especially important for female donors, who have lower iron reserves due to loss of iron in menstrual periods and reduced iron reserves. Frequent donors (males donating 3 or more times a year and females donating 2 times a year or more) may need iron supplements to make up for iron lost in donations.
Iron is an "enabler", an essential mineral found in every cell in your body. Iron is an important element in:
- Helping build red blood cells
- Helping cells work in your body
- Carrying oxygen from your lungs to every cell in your body
- Helping you concentrate
How much iron do I need?
The amount of iron you require depends on your age, gender, body type and diet. For example, women not only require more iron than men - they tend to consume less iron in their daily diets. Vegetarians, regardless of gender, often consume less iron. Frequent donors have particularly high iron needs.
How is iron measured?
The amount of iron reserves can be estimated by measuring ferritin levels. Ferritin levels are not measured on blood donors. Your fingerstick hemoglobin test may be normal, even if your iron reserves are low. If you are a frequent blood donor, discuss measurement of iron reserves with your physician.
Who needs iron?
Everyone, particularly blood donors!
Who gets the least amount?
If you tend to avoid red meat, skip meals, eat less in order to lose weight, or drink tea or coffee with your meals, you are probably not getting enough iron. If you do not eat any meat, fish or poultry, you'll need to consume more iron than people who do. If you are a woman with heavy menstrual periods, you may require more iron.
Which foods have the most iron?
Iron comes in two forms:
- Heme iron, which is easily absorbed by your body. Foods with heme iron include beef, lamb, pork, liver, veal, chicken, turkey (the dark meat has more iron), fish and seafood.
- Non-heme iron, which is absorbed less readily. Foods with non-heme iron include breakfast cereals (fortified with iron), breads and pasta (whole grain and enriched), lentils, dried peas and beans, tofu, seeds and nuts (pumpkin, sesame or peanut), dried fruit (raisins or apricots), dark green, leafy vegetables, and eggs.
It can be difficult to get enough iron through your diet, especially if you would like to donate blood more frequently. It may be helpful to take a vitamin supplement that includes iron. If you are donating blood frequently (2 or more times a year for females and 3 or more times a year for males), the amount of iron found in most multivitamins may not be adequate to meet your iron needs, and iron supplements may be necessary. We suggest that you discuss iron supplements with your physician.
I am taking iron, can I donate blood?
If you are taking a vitamin supplement that includes iron, or an iron supplement to prevent iron deficiency, you may donate blood. If you have been told by your physician that your iron reserves (ferritin) are low, you should not return to donate until your iron reserves have returned to normal.
Help yourself, and help save lives
With sufficient iron, you'll tend to feel better and look better. You'll have more energy and concentration. You will also be more able to continue to donate blood regularly and safely. Canadian Blood Services suggests increasing your daily iron consumption between now and your next blood donation. If you are a frequent donor, discuss blood donation with your physician. He or she can perform a blood test to measure your iron reserves (ferritin) and recommend iron supplements, if needed. The need for blood is growing every day in Canada. Please help save lives by giving blood. For more information, or to make an appointment to give blood, call 1 888 2 DONATE (1-888-236-6283).
I have been diagnosed with hemochromatosis – should I donate?
Hereditary hemochromatosis is a common genetic disorder. Individuals with hemochromatosis absorb too much iron from their diet, and may accumulate extra iron in vital organs. Because red blood cells contain so much iron, phlebotomy is the usual treatment for hemochromatosis. If you are otherwise eligible to donate blood, regular blood donation can be both part of your treatment and help save lives. Whole blood donations can be made every 56 days. More information can be found on the website of the Canadian Hemochromatosis Society.
Additional information for physicians
All donors undergo hemoglobin screening prior to each donation, and will be deferred for 56 days if they do not meet the regulatory requirement for blood donation. Hemoglobin testing on whole blood donors is performed on a finger stick capillary blood sample using a portable hemoglobinometer. This method is less precise than a hemoglobin determination performed on a venepuncture sample, and analysed in a laboratory. Low values may be obtained due to technical difficulties in obtaining a capillary sample, or measurement imprecision, rather than actual anemia. The regulatory requirement for whole blood donation in Canada is a minimum hemoglobin level of 125 g/L (12.5 g/dL).
Donor iron stores
Approximately 225 mg are lost with each whole blood donation of 525 ml. Female donors who donate 2 or more times a year, and male donors who donate 3 or more times a year are at higher risk of developing iron deficiency. We are advising regular blood donors to discuss blood donation with their physician at their regular check-up visit. We recommend measurement of ferritin in frequent blood donors, even if hemoglobin levels are normal. Iron supplementation and reduced frequency of donation may be indicated if iron stores are depleted. Additional investigations for underlying pathology may also be indicated, depending on a variety of factors, such as patient age and gender, symptoms or signs, results of initial laboratory testing, and response of anemia to iron supplementation and reduced frequency of donation.
Deferred female donors
Approximately 10% of female donors do not meet hemoglobin criteria on a given donation attempt. Many of these individuals are not actually anemic, have a hemoglobin level very close to the acceptability level of 125 g/L, and will be able to donate successfully on future attempts. Others may have mild anemia related to low intake of dietary iron and/or heavy loss of iron in menses. As with all regular female donors, iron stores may be depleted, even if hemoglobin levels are normal or close to normal. Approximately 1% of female donors have a hemoglobin level below 110 g/L, and are most likely to be truly anemic. These donors are advised to see their physicians in order to confirm the diagnosis of anemia on a venepuncture sample. If anemia is truly present, additional history and investigation may be indicated, and these individuals should be advised not to return to donate blood, unless the anemia is completely resolved and iron stores are adequate.
Deferred male donors
Less than 0.5% of male donors are deferred due to hemoglobin levels below the acceptability level of 125 g/L. As this is well below the normal hemoglobin level for males, these donors are advised to see their physicians in order to confirm the presence of anemia on a venepuncture sample. If anemia is confirmed, additional history and investigation may be indicated. In some cases, iron deficiency anemia may be related to frequent blood donations made by extremely dedicated donors. However, in other cases, underlying conditions leading to decreased iron absorption or gastrointestinal blood loss may be present. These individuals should be advised not to return to donate blood, unless investigations have been completed, anemia is resolved, and iron stores are adequate.