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Hemoglobin levels

Written by Ada’s Medical Knowledge Team

Updated on

What are hemoglobin levels?

A person’s hemoglobin levels indicate how much hemoglobin is present in their blood. Hemoglobin, also written as haemoglobin, is a complex protein found in red blood cells which helps to circulate oxygen around the body and transport carbon dioxide from tissues to the lungs. 1

If a person’s hemoglobin levels are either too low or too high compared to the normal hemoglobin levels, this can have a variety of consequences for one’s health.

High levels of hemoglobin are relatively rare, while low levels, a condition known as anemia, are relatively common and can occur in people of all ages. Although they are especially common in pregnant women and people experiencing a range of other conditions. Treating both high and low levels of hemoglobin usually involves treatment for the underlying cause.

How are hemoglobin levels measured?

Hemoglobin is measured as part of a complete blood count (CBC), a routine test that is commonly ordered by doctors to help diagnose a range of conditions, such as infection, anemia and leukemia.

To carry out a CBC, a blood sample – typically from a vein in the arm – first has to be taken. To measure hemoglobin, the blood will generally be combined with a liquid containing cyanide, which binds tightly to the hemoglobin molecules. By shining a light through the resulting solution (cyanmethemoglobin) and recording the amount of light which is absorbed, the levels of hemoglobin in the blood can be determined.

Read more about how to interpret blood test results »

Normal hemoglobin levels by age

Normal hemoglobin levels in the blood typically depend on sex, age and general health. Abnormally low or high levels of hemoglobin can indicate a range of health conditions, including anemia and sickle cell disease.

The hemoglobin levels chart below outlines normal hemoglobin ranges according to Medscape: 2

  • Newborn: 14-24 g/dL
  • 0-2 weeks: 12-20 g/dL
  • 2-6 months: 10-17 g/dL
  • 6 months-1 year: 9.5-14 g/dL
  • 1-6 years: 9.5-14 g/dL
  • 6-18 years: 10-15.5 g/dL
  • Adult men: 14-18 g/dL
  • Adult women: 12-16 g/dL
  • Older adults: Slight decrease in values
  • Pregnant people: >11 g/dL

Low hemoglobin levels

Having abnormally low hemoglobin generally results in a condition known as anemia. In some cases, this is associated with sickle cell disease, sickle cell anemia or thalassemia.

If you are experiencing symptoms that may be linked to low hemoglobin levels, start a symptom assessment with the free Ada app now.


Anemia, also written as anaemia, is the general name for a condition where the body either cannot make enough healthy red blood cells and/or has too little hemoglobin, the substance that enables red blood cells to transport oxygen around the body.

Read more about anemia »

Sickle cell disease

Sickle cell disease (SCD) is an umbrella term for a group of conditions that cause hemoglobin to be abnormally shaped and red blood cells to break down more easily than normal. Sickle cell disease is acquired genetically.

Read more about sickle cell disease »

Sickle cell anemia

Sickle cell anemia is one of the main subtypes of sickle cell disease.

Read more about the subtypes of sickle cell disease »


Thalassemia is a genetic disorder that affects the production and function of hemoglobin, causing red blood cells to break down more easily than normal. The condition may be mild or severe.

Read more about thalassemia »

Low hemoglobin levels in pregnancy

Mild anemia is normal during pregnancy. When pregnant, the amount of blood produced by the body increases by up to 30 percent, meaning that the body requires more iron in order to produce sufficient hemoglobin. If the body does not receive a sufficient amount of iron to do this, anemia can result. This is especially common in the second and third trimesters. 3

Preventing anemia during pregnancy

Eating a diet containing large amounts of iron-rich foods, such as green leafy vegetables, cereals, eggs, lentils, beans, peas, flaxseeds and nuts, is a good way of increasing hemoglobin levels and preventing anemia during pregnancy.

Doctors will also generally suggest over-the-counter supplements or prescribe iron supplements to ensure an individual is consuming the recommended daily amount of iron, i.e. around 27 mg. 4 Some juices made of highly-concentrated fruit extracts contain high levels of iron, so not all doctors will find it necessary to prescribe supplements.

High hemoglobin levels

High levels of hemoglobin can occur due to a number of underlying conditions and certain environmental/lifestyle factors, many of which function to lower the level of oxygen in the blood (hypoxia), causing the body to produce elevated levels of hemoglobin.

High levels of hemoglobin are relatively rare compared to low levels. Factors which can cause high hemoglobin levels include: 5

  • Using tobacco products. Research suggests that tobacco has the effect of raising hemoglobin levels in the blood.
  • Living at high altitudes
  • Dehydration
  • Bone marrow disorders (polycythemia vera)
  • Heart problems
  • Lung problems, such as emphysema
  • Anabolic steroid abuse

Symptoms of high hemoglobin levels

Due to its rarity, high levels of hemoglobin may, in many cases, only be detected by chance or after symptoms have already begun to present themselves. High hemoglobin levels may often be indicated by the presence of symptoms related to the causal underlying condition.

Experiencing high levels of hemoglobin can indicate a serious underlying condition, and urgent medical assistance should be sought.

Treatment for high hemoglobin levels

Treatment for high levels of hemoglobin depends upon the underlying cause of the condition. This may involve lifestyle changes, such as quitting smoking or more complex treatment methods to manage heart problems, for example.

Hemoglobin levels FAQs

Q: What are normal hemoglobin levels in infants?
A: Normal hemoglobin levels in infants are as follows: 2

  • Newborn: 14-24 g/dL
  • 0-2 weeks: 12-20 g/dL
  • 2-6 months: 10-17 g/dL
  • 6 months-1 year: 9.5-14 g/dL

These ranges have been calculated using a range of medical sources. Normal hemoglobin ranges typically differ between laboratories, however, meaning some sources may differ from the levels stated here.

Q: What are normal hemoglobin levels in children and adults?
A: Hemoglobin levels differ according to age, sex and general health. Normal ranges are as follows: 2

  • 1-6 years: 9.5-14 g/dL
  • 6-18 years: 10-15.5 g/dL
  • Adult men: 14-18 g/dL
  • Adult women: 12-16 g/dL
  • Older adults: Slight decrease in values
  • Pregnant people: >11 g/dL

Normal hemoglobin ranges typically differ between laboratories, meaning the ranges stated here may be slightly different to those stated elsewhere.

Q: How can I increase my hemoglobin levels?
A: Various minerals and vitamins can help to increase one’s hemoglobin count. These include iron, vitamin B6, vitamin B9 (folic acid), vitamin B12 and vitamin C. People with low hemoglobin levels may be prescribed supplements of one or more of these to help the body to produce more of the protein. Alternatively, various foodstuffs also contain these vitamins and minerals.

Foods that may help to increase hemoglobin levels include: 6

  • Iron: Egg, cereals, green leafy vegetables, beans, meat and seafood
  • Vitamin B6: Meat, fish, vegetables, nuts and seeds
  • Vitamin B9 (folic acid): Green leafy vegetables, beans and fruits
  • Vitamin B12: Fish, meat and dairy
  • Vitamin C: Citrus fruits, broccoli, potatoes and tomatoes

When hemoglobin levels are severely low, a blood transfusion will typically be carried out to rapidly bring up an individual’s hemoglobin levels.

Q: What are dangerously low hemoglobin levels?
A: When hemoglobin levels become dangerously low, a blood transfusion will normally be required. The point at which a blood transfusion may be required varies between people, as the same level of hemoglobin can cause different symptoms or dangers in different people. The general health, age, sex and other factors will always be taken into consideration when deciding whether an individual is in need of a blood transfusion. 7

According to the Association for the Advancement of Blood & Biotherapies (AABB), a hemoglobin level of 7 m/dL or below should indicate the need for a blood transfusion in people who are otherwise medically stable. For those undergoing orthopedic or cardiac surgery, or for those with a preexisting cardiovascular condition, the threshold for blood transfusion should be a hemoglobin count of 8 m/dL or below.

Q: Can the use of tobacco products affect hemoglobin levels?
A: Research suggests that tobacco has the effect of raising hemoglobin levels in the blood. 8 People who consume tobacco products, in particular people who smoke,´and who are experiencing high levels of hemoglobin, will be advised to quit the habit by medical professionals.

Q: Why are hemoglobin levels lower in females than in males?
A: Menstruation is the key reason why hemoglobin levels are, on average, lower in females than in males. Menstruation leads to loss of iron, which in turn contributes to lowering the levels of hemoglobin in the blood. This is why hemoglobin levels in pre-menstruation and post-menopausal women are generally similar to those of men. 9

Q: Why do infants have high hemoglobin levels?
A: Newborn babies typically have higher hemoglobin levels than older children and adults. The developing body of a baby consumes an elevated amount of oxygen, roughly three times that of adults based on weight, which in turn increases the need for hemoglobin. A hemoglobin count of 15 gm/dL is considered optimum for newborn babies. 10

Q: What is hemoglobin A1c?
A: Hemoglobin A1c, or HbA1c, refers to glycated hemoglobin. It is produced when red blood cells join with glucose in the blood. Measuring HbA1c gives doctors an idea of a person’s overall glucose levels over a period of weeks or months. This measurement is important for people with diabetes, as high A1c levels may indicate a higher chance of developing diabetes-related complications. 11