Hemoglobin
What does hemoglobin do?
Hemoglobin transports oxygen to (and removes carbon dioxide from) our organs and tissues. The hemoglobin molecule contains iron, an essential mineral found in our diet. When a donor donates blood, they’re also donating some of their hemoglobin. That’s why it’s important for donors to consider their iron stores.
What are normal hemoglobin levels?
Normal hemoglobin levels differ depending on several factors, including age, sex at birth, hormonal supplementation, altitude of residence as well as presence of different hemoglobin types that impact hemoglobin turnover and affinity for oxygen binding.
Hemoglobin levels may also vary depending on they are measured, for example, being measured using a sample from the vein or with a finger prick.
Normal hemoglobin levels in humans can vary greatly, usually between 120 g/L to 175 g/L.
Why does Canadian Blood Services measure hemoglobin levels?
For whole blood and platelet donation, donors registered as male must have a hemoglobin level of at least 130 g/L and donors registered as female must have a hemoglobin level of at least 125 g/L.
For plasma donation, the donor’s hemoglobin level must be at least 125 g/L, regardless of gender.
Why is there a minimum hemoglobin level requirement for donors?
Blood donation, through removal of red blood cells, leads to removal of hemoglobin. Donors may develop low hemoglobin levels or anemia.
To ensure donors have sufficient blood levels after donation and to prevent anemia, a minimum hemoglobin level is required before each donation. This required hemoglobin level cut-off is slightly higher than what a healthcare provider may use to diagnose anemia.
Related FAQs
Why are there different hemoglobin level requirements based on donors’ gender at registration?
For whole blood the minimum hemoglobin level required is different based on donors’ gender at registration. Hemoglobin level requirement is 125g/L for donors registered as female and 130g/L for donors registered as male.
Every person’s hemoglobin level is different. This is because there are many processes within the human body that impact hemoglobin levels. These include, and are not limited to, levels of sex-hormones that determine circulating testosterone levels or have impact on menstrual blood losses. Other factors include nutrition, altitude where people reside, other inherited conditions, etc. The gendered minimum hemoglobin level threshold is only an approximation to ensure there is sufficient time for blood level recovery from blood donation and for hemoglobin levels to be optimal for day-to-day functioning.
After a plasma or platelet donation, hemoglobin levels do not fall drastically. The recovery from this smaller hemoglobin loss can occur quickly for all donors, so the minimum hemoglobin level required for all donors is the same at 125g/L.
How is hemoglobin measured at donation appointments?
We check each donor’s hemoglobin level at the clinic before every donation with a fingerstick test. Our devices use a very small amount of blood from fingertips and provide a result in real-time.
What does it mean to have a fingerstick hemoglobin level too low to donate?
To ensure donors have sufficient blood levels after donation and to prevent anemia, a minimum hemoglobin level is required at each donation. This required hemoglobin level cut-off is slightly higher than what a healthcare provider may use to diagnose anemia. When a donor does not meet the minimum hemoglobin level cut-off required for donation, they may not have anemia.
For instance, the threshold for plasma donation is 125g/L. If our donor’s testing shows a level of 124g/L, they do not meet the criteria to donate plasma. This doesn’t necessarily mean they have low hemoglobin or anemia.
What are the causes of low hemoglobin?
Low hemoglobin levels, called anemia, may be a symptom of several conditions, both inherited or acquired later in life. These may include bleeding, blood breakdown, nutritional deficiencies (such as low Vitamin B12 or folate or iron), from repeated blood donation or blood tests, kidney or heart or liver disease, problems in the production of blood in the bone marrow, inherited hemoglobin or red cell disorders (for example thalassemia) and even different kinds of cancer.
How can donating blood become a potential cause of low hemoglobin?
When people donate whole blood, red cells that have hemoglobin and iron are removed.
Each whole blood donation reduces hemoglobin levels by approximately 10 g/L and reduces the body’s iron stores.
Donors produce new blood to replenish the donation. Iron is an essential building block of blood. If a donor’s iron levels are low, their body may have more difficulty replenishing blood, which means their hemoglobin does not return to prior levels and lower hemoglobin and/or anemia can develop.
What can I do if I have low hemoglobin?
Here are some things somebody could do to improve their hemoglobin levels:
- Try to increase iron-rich foods in their diet
- Reduce their blood donation frequency
- Speak to their healthcare practitioner about hemoglobin testing, iron level (ferritin) testing and iron supplementation
When can I come back to donate?
If a donor is unable to donate because of low hemoglobin it is to protect their health. Most people who have low hemoglobin recover and return to donate.
It can take four to six months to replenish iron stores. If a donor’s healthcare practitioner has started them on iron pills, they may return to donate six months after starting them, provided that their hemoglobin and iron levels have recovered. If a donor plans to donate regularly, they should speak to their healthcare provider about taking iron supplementation to prevent low iron levels.
They should also consider limiting how often they donate blood to two to three times a year.
Can a person have high hemoglobin levels?
Yes. High hemoglobin can occur. Polycythemia is a term reserved for when there is too much red blood cell production. The red blood cell quantity is indirectly measured with hemoglobin, hence often, those with “high hemoglobin” are also labelled with the clinical diagnosis of “polycythemia”.
What are the causes of high hemoglobin?
Some causes of high hemoglobin (polycythemia) include smoking, testosterone supplementation, lung problems, kidney problems, and issues with how their bone marrow makes blood (blood cancers).
Some of the causes of high hemoglobin may also prevent a person from donating, either for their wellbeing or recipient safety. Therefore, additional information may be required from their healthcare practitioner to determine eligibility.