Hematocrit Ranges (Normal, High, Low)

The hematocrit is the proportion, by volume, of the blood that consists of red blood cells. The hematocrit (hct) is expressed as a percentage. For example, a hematocrit of 25% means that there are 25 milliliters of red blood cells in 100 milliliters of blood.

The hematocrit is typically measured from a blood sample by an automated machine that makes several other measurements of the blood at the same time. Most of these machines in fact do not directly measure the hematocrit, but instead, calculate it based on the determination of the amount of hemoglobin and the average volume of the red blood cells. This is a standard part of the hct blood test that helps evaluate your blood.

The hematocrit can also be determined by a manual method using a centrifuge. When a tube of blood is centrifuged, the red cells will be packed into the bottom of the tube. The proportion of red cells to the total blood volume can then be visually measured.

The normal ranges for hematocrit depend on the age after adolescence and the sex of the individual. Hematocrit normal ranges by age chart are shown here:

These normal range values may vary slightly among different laboratories.

A person who has a low hematocrit is referred to as being anemic. There are many reasons for anemia. Some of the more common reasons that make hematocrit low are

• loss of blood (traumatic injury, surgery, bleeding, and colon cancer),
• nutritional deficiency (iron, vitamin B12, folate),
• bone marrow problems (replacement of bone marrow by cancer),
• suppression by chemotherapy drugs, kidney failure, and
• abnormal hemoglobin (sickle cell anemia).

Many diseases and conditions that impact the body's capacity to produce or retain healthy red blood cells can result in low hematocrit levels. They include:

• Anemia: Low hematocrit is usually caused by anemia. There are various forms of anemia.
  • Iron deficiency anemia: Caused by a deficiency in iron, which is essential for the production of hemoglobin, the oxygen-carrying protein found in red blood cells.
  • Vitamin-deficiency anemia: Results from deficiencies in vitamins such as B12 or folate, which are crucial for red blood cell production.
  • Hemolytic anemia: Occurs when red blood cells are destroyed faster than they can be produced.
  • Aplastic anemia: A rare condition in which the bone marrow fails to produce enough red blood cells.
• Chronic kidney disease (CKD): The kidneys produce erythropoietin, a hormone that stimulates the bone marrow to produce red blood cells. CKD leads to reduced erythropoietin production, resulting in low hematocrit levels.
• Chronic diseases: Conditions such as cancer, HIV/AIDS, and chronic liver disease can also lead to low hematocrit due to the body’s impaired ability to produce or maintain healthy red blood cells.
• Chronic inflammatory diseases: Disorders such as lupus and rheumatoid arthritis can induce persistent inflammation, which can impede the synthesis of red blood cells and result in low hematocrit.
• Bone marrow disorders: Low hematocrit can result from diseases that impair the bone marrow's ability to produce red blood cells, such as leukemia, multiple myeloma, and myelodysplastic syndromes.
• Blood loss: Significant blood loss from injuries, surgery, gastrointestinal bleeding (such as ulcers or hemorrhoids), or heavy menstrual periods can lead to low hematocrit as the body loses red blood cells faster than it can replace them.
• Thalassemia: A hereditary condition that affects hemoglobin production, leading to smaller and fewer red blood cells and decreased hematocrit levels.
• Malnutrition: Inadequate nutrition, particularly deficiencies in iron, folate, and vitamin B12, can impair red blood cell production and result in low hematocrit.
• Infections: Some infections, particularly those affecting the bone marrow or causing prolonged inflammation, can lead to low hematocrit levels.

Treatment for low hematocrit, which often indicates anemia, is based on addressing the underlying cause. Various approaches may be used, including:

• Dietary changes: If low hematocrit is due to iron deficiency, incorporating iron-rich foods such as red meat, beans, lentils, spinach, and fortified cereals can help improve levels. Additionally, consuming foods high in vitamin C, like oranges, tomatoes, and strawberries, can enhance iron absorption.
• Iron supplements: When dietary changes alone are insufficient, iron supplements may be recommended by your doctor. While iron is typically taken orally, intravenous iron may be used in certain cases if oral supplements are not effective.
• Treatment of underlying conditions: Addressing the root cause is crucial if low hematocrit is related to chronic conditions such as renal disease or inflammatory disorders. Managing the underlying condition through appropriate medication can help improve red blood cell production and hematocrit levels.
• Vitamin supplements: For low hematocrit caused by deficiencies in vitamins like B12 or folate, supplements can be beneficial. These vitamins are essential for the production of red blood cells.
• Blood transfusions: In severe cases where hematocrit levels are critically low, a blood transfusion may be necessary to quickly increase the number of red blood cells.
• Erythropoiesis-stimulating agents (ESAs): For some patients, particularly those with chronic kidney disease, doctors may prescribe ESAs to stimulate the bone marrow to produce more red blood cells.

Your doctor may tailor your treatment plan according to your specific health conditions.

Higher than normal hematocrit levels represent abnormally elevated red blood cell counts.

• High hematocrits can be seen in people living at high altitudes and in chronic smokers.
• Dehydration produces a falsely high hematocrit that disappears when the proper fluid balance is restored.

Some other infrequent causes that make hematocrit high are

• lung disease,
• certain tumors,
• a disorder of the bone marrow known as polycythemia rubra vera, and
• abuse of the drug erythropoietin (Epogen) by athletes for "blood doping" purposes.

• What does it mean when your hematocrit is low? When your hematocrit level is low, it means your blood contains fewer red blood cells than usual. This may indicate anemia, which could be caused by a variety of conditions such as iron deficiency, chronic disease, or blood loss.
• What if the hematocrit is high? When your hematocrit level is high, your blood contains a higher percentage of red blood cells than usual. This may imply dehydration, polycythemia vera (a bone marrow illness), or living at high altitudes. High hematocrit levels indicate that your blood is thicker, which increases the risk of blood clots.
• What is the difference between hemoglobin and hematocrit? Hemoglobin is the protein in red blood cells responsible for transporting oxygen throughout the body. Hematocrit, on the other hand, measures the percentage of your blood that is made up of red blood cells. While hemoglobin indicates the maximum amount of oxygen your blood can carry, hematocrit reflects the proportion of blood volume occupied by red blood cells.