Low Hemoglobin


What is low hemoglobin?

Hemoglobin is a protein in your red blood cells. Your red blood cells carry oxygen throughout your body. Oxygen powers your cells and gives you energy. A low hemoglobin level may be a sign of several conditions, including different kinds of anemia and cancer.

What happens when hemoglobin is low?

If a disease or condition affects your body’s ability to produce red blood cells, your hemoglobin levels may drop. When your hemoglobin level is low, it means your body isn’t getting enough oxygen, making you feel very tired and weak.

At what level is hemoglobin dangerously low?

Normal hemoglobin levels are different for men and women. For men, a normal level ranges between 14.0 grams per deciliter (gm/dL) and 17.5 gm/dL. For women, a normal level ranges between 12.3 gm/dL and 15.3 gm/dL. A severe low hemoglobin level for men is 13.5 gm/dL or lower. For women, a severe low hemoglobin level is 12 gm/dL.

What tests do healthcare providers use to diagnose low hemoglobin?

Healthcare providers diagnose low hemoglobin by taking samples of your blood and measuring the amount of hemoglobin in it. This is a hemoglobin test. They may also analyze different types of hemoglobin in your red blood cells, or hemoglobin electrophoresis.

Possible Causes

What causes hemoglobin levels to go low?

Several factors affect hemoglobin levels:

  • Your body doesn’t make enough red blood cells. Your body produces red blood cells and white blood cells in your bone marrow. Sometimes, conditions and diseases affect your bone marrow’s ability to produce or support enough red blood cells.
  • Your body produces enough red blood cells, but the cells are dying faster than your body can replace them.
  • You’re losing blood from injury or illness. You lose iron anytime you lose blood. Sometimes, women have low hemoglobin levels when they have their periods. You may also lose blood if you have internal bleeding, such as a bleeding ulcer.
  • Your body can’t absorb iron, which affects your body’s ability to develop red blood cells.
  • You’re not getting enough essential nutrients like iron and vitamins B12 and B9.

What affects red blood cell production?

Your bone marrow produces red blood cells. Diseases, conditions and other factors that affect red blood cell production include:

  • Lymphoma. Lymphoma is a term for cancers in your lymphatic system. If you have lymphoma cells in your bone marrow, those cells can crowd out red blood cells, reducing the number of red blood cells.
  • Leukemia. Leukemia is cancer of your blood and bone marrow. Leukemia cells in your bone marrow can limit the number of red blood cells your bone marrow produces.
  • Anemia. There are many kinds of anemias involving low hemoglobin levels. For example, if you have aplastic anemia, the stem cells in your bone marrow don’t create enough blood cells. In pernicious anemia, an autoimmune disorder keeps your body from absorbing vitamin B12. Without enough B12, your body produces fewer red blood cells.
  • Multiple myeloma. Multiple myeloma causes your body to develop abnormal plasma cells that may displace red blood cells.
  • Myelodysplastic syndromes. This condition happens when your blood stem cells don’t become healthy blood cells.
  • Chronic kidney disease. Your kidneys make a hormone that signals your bone marrow to make red blood cells. Chronic kidney disease affects this process.
  • Antiretroviral medications. These medications treat certain viruses. Sometimes, these medications damage your bone marrow, affecting its ability to make enough red blood cells.
  • Chemotherapy. Chemotherapy may affect bone marrow cells, reducing the number of red blood cells your bone marrow produces.

What affects red blood cell lifespan?

Your bone marrow constantly produces red blood cells. Red blood cells live about 120 days in your bloodstream.

Some factors that affect that lifespan include:

  • Enlarged spleen (splenomegaly). Your spleen filters red blood cells as the cells move through your body. It traps and destroys damaged or dying red blood cells. Some diseases cause your spleen to increase in size. When this happens, your spleen traps more red blood cells than usual, essentially ending those cells’ lifespan earlier than usual.
  • Sickle cell anemia. This is a blood disease that affects your hemoglobin.
  • Thalassemias. These are blood disorders that affect your body’s ability to make hemoglobin and red blood cells.

Care and Treatment

How do you fix low hemoglobin?

Healthcare providers treat low hemoglobin by diagnosing the underlying cause. For example, if your hemoglobin levels are low, your healthcare provider may do tests that reveal you have iron-deficiency anemia. If that’s your situation, they’ll treat your anemia with supplements. They may recommend you try to follow an iron-rich diet. In most cases, treating the underlying cause of anemia will bring the hemoglobin level up.

What can I do at home to treat low hemoglobin?

Many things can cause low hemoglobin, and most of the time you can’t manage low hemoglobin on your own. But eating a vitamin-rich diet can help maintain your red blood cells. Generally speaking, a balanced diet with a focus on important nutrients is the best way to maintain healthy red blood cells and hemoglobin. Here are some suggestions:

  • Red meat (beef) and meat from the organs, like liver.
  • Fish.
  • Leafy vegetables, like kale and spinach.
  • Lentils, beans and peas.
  • Nuts and dried berries.

When to Call the Doctor

When should I call my healthcare provider?

If you have a disease or condition that affects your hemoglobin levels, you should call your healthcare provider anytime your symptoms worsen.

A note from Cleveland Clinic

If you have blood test results that show your hemoglobin level is lower than normal, it means you have fewer red blood cells doing essential work — that is, carrying oxygen throughout your body. A low hemoglobin level may not be a cause for alarm. Many things affect hemoglobin levels. If your test results show low hemoglobin levels, your healthcare provider will explain why you have this symptom, what it means and how it will be treated.

Last reviewed by a Cleveland Clinic medical professional on 05/04/2022.


  • American Society of Clinical Oncology. Anemia. (https://www.cancer.net/coping-with-cancer/physical-emotional-and-social-effects-cancer/managing-physical-side-effects/anemia) Accessed 5/4/2022.
  • Baldwin C, Pandey J, Olarewaju O. Hemolytic Anemia. (https://www.ncbi.nlm.nih.gov/books/NBK558904/?msclkid=b8076e40a9e111eca812a958c9ddec1b) [Updated 2021 July 27]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan-. Accessed 5/4/2022.
  • National Cancer Institute. Understanding Laboratory Tests Fact Sheet. (https://www.cancer.gov/publications/fact-sheets?msclkid=7446ef3fa9e111ec86449ced5f55f9e4) Accessed 5/4/2022.
  • Merck Manuals. Enlarged Spleen. (https://www.merckmanuals.com/home/blood-disorders/spleen-disorders/enlarged-spleen?msclkid=46277053a9e211ecaa9aaec74a1acaf8) Accessed 5/4/2022.

Cleveland Clinic is a non-profit academic medical center. Advertising on our site helps support our mission. We do not endorse non-Cleveland Clinic products or services. Policy