Complete blood count (CBC) test: A blood analysis which provides levels for both hemoglobin and hematocrit.

Hematocrit: The percentage of red blood cells in a blood sample.

Hemoglobin: A protein carried by red blood cells that transports and delivers oxygen throughout the body.

Iron: A nutrient in your diet essential in the process of making red blood cells.

Iron deficiency: A shortage or low level of iron in the body, which can lead to anemia.

Stored iron: Nutrients in the liver and bone marrow that are available for use in making red blood cells.

Vitamin deficiency: A shortage or low level of vitamins. Reduced amounts of vitamin B6, vitamin B12 or folic acid may result in anemia.

Causes for Deferral

Iron/Vitamin Deficiency

Donating blood is a great way to help your community, but sometimes you can be turned down from donating because your blood count is too low. This is called being "deferred" and about 10% of people who attempt to donate are deferred because of a low blood count.1 Don't feel bad if you were deferred for this reason because it is one of the most common reasons people are not allowed to donate blood.2 After testing a sample of your blood, you may have been told your "iron is low," you have a "low blood count," "low hemoglobin" or "low hematocrit." Essentially, each of these terms means you do not have enough red blood cells in your body to donate blood.

The medical term for a lower than normal blood count is anemia and there are many reasons why it can develop. One common cause may be that your body does not have enough iron or vitamins to make healthy red blood cells. Even though you were not allowed to donate on a particular day due to low blood count, there are usually some simple measures you can take to raise your level.

How does my body use iron and vitamins?

Iron and vitamins are the nutrients that are found in foods we eat. Iron builds muscle proteins, healthy bones, and most importantly, it helps make red blood cells.14 In the blood, these cells carry oxygen from your lungs to all parts of your body. When your body does not have enough iron it is called iron deficiency, and it can make you feel tired or even cause damage to your internal organs. Iron deficiency can develop into anemia when the body has had a low level of iron for a long time.

When it comes to vitamins, each one has a special role to play. For example, folic acid is necessary for DNA synthesis and very important in making white and red blood cells.15 Vitamin B6 and vitamin B12 are also needed for blood cell production and B12 also helps maintain healthy nerves.16 These are just a few of the vitamins your body needs, but they are the most important ones related to making red blood cells.

What can cause my body to be low in iron or vitamins?

Your iron or vitamin levels can be low for many reasons. Some of the most common reasons include not eating enough foods that contain iron or vitamins, donating blood frequently (3 or more times per year), blood loss from menstruation, or because you cannot properly absorb iron, folate, vitamin B6 or vitamin B12.17

Additionally, bleeding from your digestive tract is another reason your iron or vitamin levels may be low. This type of blood loss can be caused by stomach ulcers, growths in the intestines (polyps), certain medications, colon cancer, or other diseases and infections of the digestive tract.18

How can I tell if I have a low blood count because of an iron or vitamin deficiency?

If you have a low blood count you do not necessarily have anemia, but you may develop anemia if your body cannot make enough healthy red blood cells because your iron or vitamin levels are low. At first, there might not be any signs that you have anemia. As anemia gets worse, you may start to notice some symptoms. General symptoms of anemia include fatigue, weakness, pale skin, chest pain, dizziness, irritability, numbness or coldness in your hands and feet, trouble breathing, a fast heartbeat, and headache.19 Another symptom that is specific to iron deficiency is called pica, which is the craving of unusual foods, most commonly ice.20 Also, a symptom specific to vitamin B12 deficiency is nerve damage in the hands and feet.21

General Healthy Hematocrit & Hemoglobin Values
  Female Male
Hemoglobin 12.3 - 15.3 g/dL 14.0 - 17.4 g/dL
Hematocrit 36.0 - 45.0% 41.5 - 50.4%
Reference ranges for illustrative purposes only and may vary by age, ethnic group and pre/postmenopausal females. Perkins S. Wintrobe's Clinical Hematology. 1998.22

To determine if you have a low blood count because of an iron or vitamin deficiency, your doctor will need to perform a routine complete blood count (CBC) test. This test assesses your levels for hemoglobin and hematocrit. Although measuring hemoglobin is the most common method used for diagnosing anemia, hematocrit values may also be used. The healthy range of these values depends on both gender and age. If your doctor determines that iron or vitamin deficiency is causing your low blood count, he or she can then discuss with you the best way to try to raise your hematocrit back to a healthy level.

Blood Count Rules

The minimum hematocrit level of 38% has been set by the FDA to ensure donors have enough blood to give and that they also have enough iron available in their bodies to make more blood after they donate. Although some men with anemia (hematocrit of 38%) can donate blood, some women who do not have anemia (hematocrit of 36-37%) are not allowed to donate blood. This is because women need more than twice as much iron as men. If a nearly anemic woman (hematocrit of 36-37%) was allowed to donate, her body might not have enough iron saved up to keep her from becoming anemic. For women, saving extra iron to correct anemia can be very difficult. If your blood count indicates you have anemia, talk with your doctor about raising your blood level.

What can I do to raise my blood count so that I can donate blood again?

The first thing to do is determine what is causing you to have iron or vitamin deficiency and then treat that cause.

The most common treatment for iron or vitamin deficiency is to eat more iron- and vitamin-rich foods. Meats are some of the best sources of iron, including beef, organ meats, pork, poultry, fish, clams, and oysters.23 Iron is found in other foods such as eggs, dairy products, and some vegetables, but it is often harder to absorb iron from these types of food. Examples of these foods include dried beans and peas, iron-fortified cereals, bread, pasta products, dark green leafy vegetables (chard, spinach, mustard greens, kale), dried fruits, nuts, and seeds. It can also be helpful to eat foods which contain vitamin C along with iron-rich foods because vitamin C helps the body absorb iron from the food you eat.24 Vitamin C can be found in citrus fruits, berries, potatoes, broccoli, sprouts, tomatoes, peppers and kiwis.

Vitamin B12 is naturally found in foods that come from animals including fish, meat, poultry, eggs, milk, and milk products.16 Fortified breakfast cereals are a particularly valuable source of vitamin B12. Foods rich in folate include citrus fruits and juices and dark green leafy vegetables. Additionally, the FDA requires that folic acid be added to breads, cereals, flours, corn meals, pastas, rice, and other grain products.15 These products are a major source of folic acid in our diet.

An iron- and vitamin-rich diet is healthy and a good way to help raise your iron and vitamin levels, but sometimes this is not enough to correct your low blood count because you may have trouble absorbing these nutrients from the foods you eat. If this is the case, your doctor may recommend you take an iron or vitamin supplement. For more information on iron supplements, please view our feature article A Patient's Guide to Oral Iron Supplements.

If your iron or vitamin deficiency is not due to an intake or absorption problem, further communication with your doctor will help him or her identify the cause of your low levels and determine the best way to manage your deficiencies.

What can I do to prevent getting low iron and vitamin levels again?

For most people, eating a balanced diet and taking a multivitamin every day will provide adequate amounts of the iron and vitamins you need to prevent deficiencies and anemia. Many of these nutritious foods are listed above. For more information about how iron- and vitamin-rich foods can help prevent anemia, read our two feature articles, Anemia and Nutrition: The Importance of Iron and The Importance of Essential Vitamins.