Hemoglobin helps red blood cells carry oxygen to your muscles and tissues. Abnormal hemoglobin levels can be a sign of several health problems.

Hemoglobin is a component of your blood that delivers oxygen throughout your body. If your hemoglobin levels are low, your cells might not get enough oxygen. As a result, you might frequently feel tired, weak, or dizzy.

This article covers what hemoglobin is, how hemoglobin levels affect your well-being, and how doctors test for and treat low hemoglobin.

Hemoglobin is a type of protein in your red blood cells that distributes the oxygen you breathe to muscles and tissues throughout your body. Without oxygen, your muscles would not have the energy they need to function normally.

Hemoglobin also picks up carbon dioxide and returns it to your lungs for you to exhale. This essential process helps prevent toxic levels of carbon dioxide.

Iron, a mineral you get from food, is a key component of hemoglobin. Iron helps hemoglobin bind to oxygen so the hemoglobin can transport the oxygen to your tissues. Iron is what makes your blood red.

Foods high in iron

  • spinach
  • nuts
  • salmon
  • beef
  • tofu
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A hemoglobin (Hgb) blood test measures the amount of hemoglobin in your red blood cells. To perform this test, a healthcare professional will take a sample of blood from your veins, usually from the crook of your arm or the back of your hand.

Your doctor might order a hemoglobin test to:

  • Check your overall health: A complete blood count is a common part of routine medical checkups. It measures your levels of hemoglobin and other blood components.
  • Screen for disorders: Symptoms such as fatigue, shortness of breath, and lightheadedness may indicate a condition that causes low hemoglobin, such as an infection or internal bleeding.
  • Monitor your condition: If you have a health condition that causes low hemoglobin or are undergoing treatment for low hemoglobin, your doctor might check your levels regularly.

An Hgb test is no different from a standard blood test and should take only a few minutes. A healthcare professional will disinfect your skin with an alcohol-based wipe. They will place an elastic band, known as a tourniquet, around your biceps and ask you to make a fist so your veins become more visible.

The healthcare professional will draw the sample by inserting a butterfly needle into your skin and collecting blood in one or more vials. They will then remove the elastic band and needle and cover the insertion site with a bandage.

They will send your blood sample to a lab for analysis, and you should get your results within a few hours or days.

Healthcare professionals measure hemoglobin in grams per deciliter of blood (g/dL).

Normal hemoglobin levels are as follows:

  • In adult males: 13.5–18 g/dL
  • In adult females: 12–15 g/dL
  • In children: 11–16 g/dL
  • During pregnancy: varied but typically greater than 10 g/dL

While there are no standardized healthy hemoglobin ranges for transgender people who are undergoing hormone therapy, a 2019 study found that healthy hematology ranges remained consistent in both cisgender and transgender males and females.

In addition to your sex, a number of other factors can affect your hemoglobin levels. For example, older adults and pregnant people tend to have lower-than-average hemoglobin levels.

Use of “male” and “female”

In this article, we use the terms “male” and “female” to refer to someone’s sex assigned at birth. For information about the difference between sex and gender, see this article.

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Low hemoglobin levels are a sign that your body doesn’t have enough red blood cells. Your body may not be producing enough on its own, or you might have a health condition that’s lowering your red blood cell count.


If your hemoglobin levels are too low, your muscle cells might not be getting enough oxygen. You might feel like you have no energy. This condition is called anemia.

Common symptoms of anemia include:

  • chest pain
  • cold hands and feet
  • dizziness
  • fatigue
  • headaches
  • irregular heartbeat
  • paler-than-usual skin
  • shortness of breath
  • weakness

Low hemoglobin levels have many possible causes. Some of the most common causes are:

  • Diet: A diet that is too low in iron, folate, or vitamin B12 can affect your body’s ability to produce hemoglobin.
  • Blood loss: Significant bleeding can lead to low hemoglobin levels, but long-term blood loss from stomach ulcers, uterine fibroids, or heavy menstrual periods can also contribute.
  • Pregnancy: During pregnancy, your blood volume increases significantly, which can lower your hemoglobin levels.
  • Genetic conditions: Hereditary health conditions such as G6PD deficiency, sickle cell anemia, spherocytosis, and thalassemia can destroy red blood cells.
  • Cancer: Certain types of cancer, including leukemia and lymphoma, can affect your red blood cell levels.
  • Chronic kidney disease: Decreased kidney function can mean that your body doesn’t make enough erythropoietin, a hormone necessary for red blood cell production.
  • Medication: Antiretroviral medications and chemotherapy drugs can damage your bone marrow, which may reduce red blood cell production.

Your doctor will recommend treatments for low hemoglobin according to the underlying cause.

If your diet is low in iron, a nutritional supplement may help increase your hemoglobin levels. Your doctor might also recommend nutritional counseling to help you select foods rich in essential vitamins and minerals.

If you have a health condition that’s causing low hemoglobin, your doctor will treat the underlying cause.

Most of the time, addressing the cause of low hemoglobin will help improve your levels. In severe cases, you may need a blood transfusion.

It’s also possible to have overly high hemoglobin levels. If you have high hemoglobin levels, you might also have a high red blood cell count. This condition is called polycythemia.

Primary polycythemia is a genetic condition linked to a mutation in the bone marrow cells.

Secondary polycythemia occurs when another condition causes an overproduction of red blood cells. Cancers and heart and lung diseases are some of the conditions linked to secondary polycythemia.

Hemoglobin is an essential component of your red blood cells that allows them to distribute oxygen throughout your body. When your hemoglobin levels are low, you might feel unusually weak or tired.

Doctors use a blood test to check your hemoglobin levels. They will usually order this test as part of a routine exam. Treatment for low hemoglobin levels depends on the cause but may include nutritional supplements.