Hemoglobin

What is hemoglobin?

Hemoglobin (Hb) is a complex protein found in red blood cells. Its primary function is to help circulate oxygen around the body and transport carbon dioxide from tissues to the lungs. Hemoglobin contains iron, which helps give blood its red color.[1]

How are hemoglobin levels measured?

Hemoglobin is measured as part of a complete blood count (CBC), also called a full blood count (FBC) – a routine test that is commonly ordered by doctors to help diagnose a range of conditions, such as infection, anemia and leukemia.[2] To carry out a CBC, a blood sample will typically be taken from a vein in the arm.

See this resource on hemoglobin levels for more information.

Hemoglobinopathy evaluation

A hemoglobinopathy evaluation might be ordered as a follow-up test to a CBC if an individual shows signs of atypically high or low levels of hemoglobin. The test is able to detect the presence of abnormal types of hemoglobin and measure their relative amounts in the blood.

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.

High hemoglobin levels

Having high levels of hemoglobin is rare in comparison to low levels. Typically, the disorder will be noticed as part of a routine blood test, and treatment will be aimed at the underlying cause of the condition in the majority of cases.[3]

The symptoms of high hemoglobin levels may often be related to the underlying condition that is causing them. See this resource on hemoglobin levels for more information.

Low hemoglobin levels (anemia)

A low hemoglobin count is commonly referred to as a condition called anemia.

Other conditions related to low hemoglobin levels include:

  • Sickle cell disease, 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.
  • Thalassemia, a genetic disorder which impairs the function of hemoglobin in the body.

Hemoglobin A1c test

The hemoglobin A1c test measures an individual's levels of blood glucose (blood sugar) over the previous three months, the typical lifespan of red blood cells. The test screens for hemoglobin A1c – also known as glycated hemoglobin or A1c – which is the product of glucose attaching to hemoglobin. This test is primarily used to diagnose, manage and research diabetes rather than to measure hemoglobin levels in general.[4][5]

Hemoglobin FAQs

Q: Can I raise my hemoglobin levels?
A: When anemia is caused by an iron deficiency, doctors may prescribe iron supplements to help boost red blood cell and hemoglobin production. It may also be advised to increase the amount of iron in one’s diet through consuming food such as:[6]

  • Leafy vegetables, such as kale and watercress
  • Fortified cereals and breads
  • Brown rice
  • Beans and pulses
  • Nuts and seeds
  • Meat, fish and tofu
  • Eggs
  • Dried fruit

Q: What is hemoglobinuria?
A: Hemoglobinuria is a term used to describe the presence of hemoglobin in the urine. Typically, hemoglobin is not present in urine, so if hemoglobinuria occurs, it may be a sign of a medical condition in need of attention. Hemoglobinuria generally makes urine appear abnormally dark in color.[7]


  1. MedicineNet. “Hemoglobin.” April 11, 2015. Accessed November 6, 2017.

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

  3. Tandurust. “Causes of High Hemoglobin Levels: Symptoms & Treatment Options.” October 7, 2015. Accessed November 6, 2017.

  4. National Institute of Diabetes and Digestive and Kidney Diseases. “The AC1 Test and Diabetes.” September, 2014. Accessed November 6, 2017.

  5. Lab Tests Online. “Hemoglobin A1C.” September 4, 2015. Accessed November 6, 2017.

  6. Patient. “Anaemia.” November 1, 2017. Accessed November 6, 2017.

  7. MedicineNet. “Hemoglobinuria.” May 13, 2016. Accessed November 6, 2017.