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Medical Author:

Siamak T. Nabili, MD, MPH

Siamak T. Nabili, MD, MPH

Dr. Nabili received his undergraduate degree from the University of California, San Diego (UCSD), majoring in chemistry and biochemistry. He then completed his graduate degree at the University of California, Los Angeles (UCLA). His graduate training included a specialized fellowship in public health where his research focused on environmental health and health-care delivery and management.

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Medical Editor:

William C. Shiel Jr., MD, FACP, FACR

William C. Shiel Jr., MD, FACP, FACR

Dr. Shiel received a Bachelor of Science degree with honors from the University of Notre Dame. There he was involved in research in radiation biology and received the Huisking Scholarship. After graduating from St. Louis University School of Medicine, he completed his Internal Medicine residency and Rheumatology fellowship at the University of California, Irvine. He is board-certified in Internal Medicine and Rheumatology.

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In this Article

• Anemia facts*
• What is anemia?
• What causes anemia?
• Can inadequate iron cause anemia?
• What about acute (sudden) blood loss as a cause of anemia?
• What are other causes of anemia?
• Can anemia be hereditary?
• What are the symptoms of anemia?
• How is anemia diagnosed?
• What is a complete blood cell (CBC) count?
• How is blood collected for a complete blood cell (CBC)?
• What is the red blood cell (RBC) count?
• What is hemoglobin?
• What does a low hemoglobin level mean?
• What is the hematocrit?
• How is hematocrit determined?
• How is anemia treated?
• What are the complications of anemia?
• What is the outlook (prognosis) for anemia?
• Blood and Bleeding Disorders FAQs
• Patient Comments: Anemia - Symptoms
• Patient Comments: Anemia - Levels
• Patient Comments: Anemia - Treatments
• Find a local Hematologist in your town
• Anemia Index

Low hemoglobin is called anemia. When there is a low hemoglobin level, there is often a low red blood cell count and a low hematocrit, too. Reference ranges are slightly different from one source to another, but typically hemoglobin of less than 13.5 gram/100 ml is abnormal in men and less than 12.0 gram/100 ml in women.

The hematocrit is specifically a measure of how much of the blood is made of red cells. The hematocrit is a very convenient way to determine whether the red blood cell count is too high, too low, or normal. The hematocrit is a measure of the proportion of blood that is composed of the red blood cells.

The red blood cells in the sample of blood are packed down by spinning the tube in a centrifuge under prescribed conditions. The proportion of the tube that consists of red blood cells is then measured. Let's say that it is 45%. The hematocrit is 45%.

The treatment of the anemia varies greatly. First, the underlying cause of the anemia should be identified and corrected. For example, anemia as a result of blood loss from a stomach ulcer should begin with medications to heal the ulcer. Likewise, surgery is often necessary to remove a colon cancer that is causing chronic blood loss and anemia.

Sometimes iron supplements will also be needed to correct iron deficiency. In severe anemia, blood transfusions may be necessary. Vitamin B12 injections will be necessary for patients suffering from pernicious anemia or other causes of B12 deficiency.

In certain patients with bone marrow disease (or bone marrow damage from chemotherapy) or patients with kidney failure, epoetin alfa (Procrit, Epogen) may be used to stimulate bone marrow red blood cell production.

If a medication is thought to be the culprit, then it should be discontinued under the direction of the prescribing doctor.