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Monday, June 17, 2019

Reasons for High red blood cell count (polycythemia)

Polycythemia (high red blood cell count) definition and facts

  • Polycythemia means increased red blood cell volume.
  • Polycythemia is divided into two main categories; primary and secondary.
  • Polycythemia can be linked to secondary causes, such as, chronic hypoxia or tumors releasing erythropoietin.
  • Abnormally increased red cell production in the bone marrow causes polycythemia vera.
  • Treatment of secondary polycythemia is dependent on the underlying condition.
  • Polycythemia is treated by phlebotomy (controlled blood letting) and hydroxyurea.

What is polycythemia?

Polycythemia definition

Polycythemia is a condition that results in an increased level of circulating red blood cells in the bloodstream. People with polycythemia have an increase in hematocrit, hemoglobin, or red blood cell count above the normal limits.
Polycythemia is normally reported in terms of increased hematocrit (hematocrit is the ratio of the volume of red blood cells to the total volume of blood) or hemoglobin concentration (hemoglobin is a protein responsible for transporting oxygen in the blood).
  • Hematocrit (HCT): Polycythemia is considered when the hematocrit is greater than 48% in women and 52% in men.
  • Hemoglobin (HGB): Polycythemia is considered when there is a hemoglobin level of greater than 16.5g/dL in women or hemoglobin level greater than18.5 g/dL in men.
Polycythemia can be divided into two categories: primary and secondary.
  • Primary polycythemia: In primary polycythemia the increase in red blood cells is caused by inherent problems in the process of red blood cell production.
  • Secondary polycythemia: Secondary polycythemia generally occurs as a response to other factors or underlying conditions that promote red blood cell production.
Red cell production (erythropoiesis) takes place in the bone marrow through a complex sequence of tightly regulated steps. The main regulator of the red cell production is the hormone erythropoietin (EPO). This hormone is largely secreted by the kidneys, although, about 10% may be produced and secreted by the liver.
Erythropoietin secretion is up-regulated in response to low oxygen levels (hypoxia) in the blood. More oxygen can be carried to tissues when erythropoietin stimulates red blood cell production in the bone marrow to compensate for the hypoxia.

What are normal ranges of hematocrit, red cell counts, and hemoglobin?

Red blood cell count ranges

  • Hematocrit is the ratio of the volume of red cells to the volume of whole blood. The normal range for hematocrit varies between sexes and is approximately 45% to 52% for men and 37% to 48% for women.
  • Red cell count signifies the number of red blood cells in a volume of blood. The normal range in men is approximately 4.7 to 6.1 million cells/ul (microliter). The normal range in women ranges from 4.2 to 5.4 million cells/ul, according to NIH (National Institutes of Health) data.
  • Hemoglobin is a protein in the red blood cells that carries oxygen and gives blood its red color. The normal range for hemoglobin may differ between the sexes and is approximately 13 to 18 grams per deciliter for men and 12 to 16 grams per deciliter for women.



Symptoms of Polycythemia or What Happens if RBC Count is High?

This is what happens if the RBC count is high; if the polycythemia is mild, then it may not produce any symptoms in the patient. Common symptoms of polycythemia or high RBC count are:

  • Blurry vision.
  • Pain in the chest.
  • Itching.
  • Headaches.
  • Dizziness.
  • Muscle pain.
  • Hypertension.
  • Ruddy complexion.
  • Ringing in the ears (tinnitus).
If a person has developed polycythemia as a result of liver cancer, kidney cancer, or other erythropoietin-secreting tumors, then symptoms include weight loss, abdominal fullness or pain and jaundice.

What causes polycythemia?


By Mayo Clinic Staff

High red blood cell count may be caused by low oxygen levels, kidney disease or other problems.

Low oxygen levels

Your body may increase red blood cell production to compensate for any condition that results in low oxygen levels, including:
  1. Heart disease (such as congenital heart disease in adults)
  2. Heart failure
  3. A condition present at birth that reduces the oxygen-carrying capacity of red blood cells (hemoglobinopathy)
  4. High altitudes
  5. COPD (chronic obstructive pulmonary disease) exacerbation — worsening of symptoms
  6. Pulmonary fibrosis (scarred and damaged lungs)
  7. Other lung diseases
  8. Sleep apnea
  9. Nicotine dependence (smoking)

Performance-enhancing drugs

Certain drugs stimulate the production of red blood cells, including:
  1. Anabolic steroids
  2. Blood doping (transfusion)
  3. Injections of a protein (erythropoietin) that enhances red blood cell production

Increased red blood cell concentration

  1. Dehydration (If the liquid component of the blood (plasma) is decreased, as in dehydration, the red blood cell count increases. This is due to the red blood cells becoming more concentrated. The actual number of red blood cells stays the same.)

Kidney disease

Rarely, in some kidney cancers and sometimes after kidney transplants, the kidneys might produce too much erythropoietin. This enhances red blood cell production.

Bone marrow overproduction

  1. Polycythemia vera
  2. Other myeloproliferative disorder

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