Hemoglobin levels

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 levels of hemoglobin are either too low or too high, 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, though 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.

What are normal hemoglobin levels?

Normal levels of hemoglobin 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.

According to the World Health Organization, normal hemoglobin levels are as follows:[2]

  • 6 months to 4 years: At or above 11 g/dL
  • 5-12 years: At or above 11.5 g/dL
  • 12-15 years: At or above 12 g/dL
  • Adult male: 13.8 to 17.2 g/dL
  • Adult female: 12.1 to 15.1 g/dL
  • During pregnancy: At or above 11g/dL

Low hemoglobin levels

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

Anemia

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.

See this resource on anemia for more information about the condition and its subtypes, including diagnosis and treatment options.

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. See this resource on sickle cell disease for more information about the condition, including diagnosis and treatment options.

Sickle cell anemia

Sickle cell anemia is one of the main subtypes of sickle cell disease. See this resource on sickle cell disease for more information about sickle cell anemia.

Thalassemia

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.

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:[3]

  • 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:[4]

  • 0-1 month: 13.3 - 19.9 gm/dL
  • 1-2 months: 10.7-17.1 gm/dL
  • 2-3 months 9.0-14.1 gm/dL
  • 3-6 months: 9.5-14.1 gm/dL
  • 6 months-1 year: 11.3-14.1 gm/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:[5]

  • Children: 11-13 gm/dL
  • Adult males: 14-18 gm/dL
  • Adult women: 12-16 gm/dL
  • Older men: 12.4-14.9 gm/dL
  • Older women: 11.7-13.8 gm/dL

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

Q: What are normal hemoglobin levels in pregnant women?
A: Normal hemoglobin levels during pregnancy are as follows:[6]

  • 1st trimester: 11.6-13.9 gm/dL
  • 2nd trimester: 9.7-14.8 gm/dL
  • 3rd trimester: 9.5-15 gm/dL

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

Q: How are hemoglobin levels measured?
A: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.[7]

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.[8]

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:[9]

  • 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: When do low hemoglobin levels become dangerous? **
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.[10]

According to the American Association of Blood Banks, 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: Why are hemoglobin levels low during pregnancy?
A: Mild anemia is normal during pregnancy. When pregnant, the amount of blood produced in body increases by up to roughly 30 percent, thereby increasing the amount of iron needed to produce hemoglobin. When 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.[11]

Q: How to increase hemoglobin levels during pregnancy?
A: Eating a diet containing large amounts of iron-rich foods such as green leafy vegetables, cereals and eggs 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 amount of iron daily, i.e. around 27 mg.[12] Some juices made of highly concentrated fruit extracts contain high levels of iron, and so not all doctors will find it necessary to prescribe pills.

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.[13] 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 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.[14]


  1. MedicineNet. “Hemoglobin.” April 11, 2015. Accessed November 13, 2017.

  2. Livestrong. “What Is a Healthy Hemoglobin Level.” August 14, 2017. Accessed November 6, 2017

  3. National Heart, Lung, and Blood Institute. “How Are Thalassemias Treated?” July 3, 2012. Accessed November 17, 2017.

  4. Tandurust. “Causes of High Hemoglobin Levels: Symptoms & Treatment Options.” October 7, 2015. Accessed November 17, 2017.

  5. Health Care. “Pediatric Reference Ranges” Accessed November 17, 2017.

  6. eMedicine. “Hemoglobin normal values.” May 13, 2016. Accessed November 17, 2017.

  7. Perinatology. “Reference Values During Pregnancy.” Accessed November 17, 2017.

  8. National Heart, Lung, and Blood Institute. “Types of Blood Test.” January 6, 2012. Accessed November 17, 2017.

  9. MD Health. “How to Increase Your Hemoglobin Level.” Accessed November 17, 2017.

  10. The JAMMA Network. “Clinical Practice Guidelines From the AABB Red Blood Cell Transfusion Thresholds and Storage.” November 15, 2016. Accessed November 17, 2017.

  11. American Society of Hematology. “Anemia and Pregnancy.” Accessed November 17, 2017.

  12. American Society of Hematology. “Anemia and Pregnancy.” Accessed November 17, 2017.

  13. Semantics Scholar. “Effect of smoking on Red Blood Cells Count, Hemoglobin Concentration and Red Cell indices.” June, 2014. Accessed November 20, 2017.

  14. NCBI. “[The critical hemoglobin value in newborn infants, infants and children].” 1992. Accessed November 20, 2017.