Hemoglobin transports oxygen from our lungs to the cells in our body. The hemoglobin molecule contains iron, an essential mineral found in our diet. Hemoglobin is an iron-rich protein in red blood cells. Oxygen entering the lungs attaches to the hemoglobin in the blood, which carries it to the tissues in the body. 

Hemoglobin FAQs

What are normal hemoglobin levels?

Normal hemoglobin levels are different in women and in men.

Normal levels for females are between 120 g/L to 160 g/L.

Normal levels for males are between 140 g/L to 180 g/L.

We test each donor’s hemoglobin at our donations centres and we require a minimum of 125 g/L (females) and 130g/L (male) to be eligible to donate at the time of your appointment.

Why does Canadian Blood Services measure hemoglobin levels?

We measure hemoglobin to protect you as a donor, and to ensure the quality of the red blood cells that will be transfused into blood recipients. It is important that you do not donate blood if your hemoglobin level is low. Donating blood with low hemoglobin levels may cause you to become anemic.

How is hemoglobin measured?

We check each donor’s hemoglobin level at the clinic before every donation with an onsite finger stick test.

What does it mean to have low hemoglobin?

The most common reason for low hemoglobin is due to low iron stores. Iron is needed to make red blood cells. Low iron stores can lead to fatigue and decreased exercise capacity.

Causes of low iron stores include: 

  • Not enough iron in your diet
  • Frequent blood donation (more than twice a year for women or three times a year for men)
  • For women, menstrual blood loss
  • More rarely, gradual bleeding in the digestive tract, such as stomach or colon.

What is anemia?

Anemia is defined as a hemoglobin level of less than 120 g/L in non-pregnant females and less than 130 g/L in males. Anemia is related to symptoms such as fatigue and lowered exercise tolerability. If your hemoglobin level is below 110 g/L, you should see your physician for further testing. If anemia is present, you should not return to donate until the cause of the low hemoglobin has been identified and corrected.

How can donating blood become a potential cause of anemia?

Frequent blood donation can contribute to anemia because a “whole blood donation” results in a drop of hemoglobin levels by approximately 10 g/L. Healthy donors produce new red blood cells to replace donated cells. However, iron is essential to the production of new red blood cells meaning, if your iron levels are low, your body may have more difficulty replenishing your red blood cells.

How to prevent anemia due to blood donation?

Donors need to have an adequate amount of iron. Frequent donors (men who donate three or more times a year and women who donate two or more times a year) may need iron supplements to make up for iron lost in donations.

What can I do if I have low hemoglobin?

We recommend that you see your doctor to check your hemoglobin levels and iron stores (ferritin). Your doctor will look into reasons why your hemoglobin is low and may suggest taking iron pills. All blood donors should eat an iron-rich diet and consider taking a multivitamin with iron.

When can I come back to donate?

Being deferred for low irons stores protects your own health. Most people who have low hemoglobin are able to improve their iron level and hemoglobin count and become eligible donors once again, provide that they meet all other eligibility criteria. It can take four to six months to rebuild your iron stores. Seek professional medical advice to help you determine when to donate again. 

If your doctor has started you on iron pills, you may return to donate six months after starting them, if your hemoglobin and iron levels are back to normal. Once your iron is back to normal, and if you plan to donate regularly, speak to your doctor or pharmacist about taking over the counter iron pills to prevent low iron. 

Consider limiting how often you donate blood to twice a year (for females) and  three times a year (for males). 

I am a healthy female donor, but I seem to fail my hemoglobin test every second time. What steps can I take to improve my hemoglobin levels?

  • Try to increase your dietary iron intake.
  • Reduce your blood donation frequency.
  • We also suggest speaking to your pharmacist or physician about the need for iron supplementation.

Learn more about irons stores under the Iron tab below.