Hemoglobin
Information for Donors:
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 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 lancet is used to obtain a drop of blood from your finger. Two methods can then be used to analyse the amount of hemoglobin. If a copper sulfate method based on the density of the blood drop suggests that hemoglobin may be low, a machine is used to determine the actual hemoglobin level. Both screening methods used in the blood donation setting are not as precise as testing preformed on a blood sample obtained in a doctor's office and 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 both men and women is 125 g/L (12.5 g/dL).
What if I don't meet minimum hemoglobin criteria?
Female donors:
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.
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.
Male donors:
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 likely 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. 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.
Can blood donation cause anemia?
Blood donation results in a drop in hemoglobin of approximately 10 g/L, 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. It is therefore very important for blood donors to have an adequate amount of iron in their diet. This is especially important for female donors, who have lower iron reserves due to loss of iron in menstrual periods and reduced iron reserves.
Iron: Your body's precious mineral
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.
Who needs iron?
Everyone.
Who gets the least amount?
If you tend to avoid red meat, skip meals, eat less in order to lose weight, 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.
Dealing with your Inhibitors: How much iron gets absorbed
It's one thing to eat foods that are rich in iron; getting your body to actually absorb this iron is another thing. It's all determined by inhibitors and enhancers - components of your diet which make iron more or less likely to be absorbed. Vitamin C, for example, enhances iron absorption, while calcium inhibits it - drinking tea or coffee with meals reduces iron absorption, because they contain inhibitors.
Please note, you may not feel immediate benefits of changing to a more iron-rich diet. It takes a few weeks for your body to react to increased iron.
Help yourself, and help save lives
With sufficient iron in your diet, you'll tend to feel better and look better. You'll have more energy and concentration. You may also be more able to donate blood - in as little as 56 days from your last clinic visit.
Canadian Blood Services suggests increasing your daily iron consumption between now and your next blood donation.
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).
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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 usually performed on a finger stick capillary blood sample, using a screening copper sulfate test. If the copper sulfate test indicates a possible low value, actual hemoglobin determination will be performed 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).
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. 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. Since blood donation results in the loss of approximately 300 mg of iron per unit, individuals with inadequate iron stores who require iron supplementation are not good candidates for donation.
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, and these individuals should be advised not to return to donate blood.
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