HCT Blood Test Causes and Treatment

The HCT blood test, a crucial component of medical diagnostics, offers valuable insights into our health. HCT, or Hematocrit, measures the proportion of red blood cells in our blood. This simple yet powerful test provides essential information about our overall blood health and can help detect various medical conditions. By understanding the significance of the HCT blood test and its implications, we can take proactive steps towards maintaining our well-being. Let’s explore how this unassuming test is pivotal in safeguarding our health and guiding medical decisions.

HCT blood test

Causes of Low HCT Levels 

  1. Anaemia: Anaemia is a condition characterise by a reduction in red blood cells or a decrease in haemoglobin levels. There are different types of anaemia, such as iron deficiency anaemia, vitamin B12 deficiency anaemia, or aplastic anaemia, which can lead to a low HCT.
  2. Blood loss: Significant loss due to trauma, surgery, gastrointestinal bleeding (e.g. ulcers, tumours), or heavy menstrual bleeding can lead to reduced HCT.
  3. Chronic diseases: definite chronic diseases, for example, kidney disease, liver disease, and autoimmune diseases, can affect red blood cell production or survival, resulting in low HCT.
  4. Nutritional deficiencies: Inadequate intake or absorption of essential nutrients such as iron, vitamin B12, or folic acid can affect red blood cell production and lead to low HCT.
  5. Bone marrow disorders: ailments that bear on the bone marrow, for example, leukaemia, myelodysplastic syndromes (MDS), or bone marrow suppression from chemotherapy, can reduce RBC production and lead to low HCT.
  6. Hemolysis: Haemolysis is the premature destruction of red blood cells, resulting in reduced lifespan and low HCT. Hemolysis can cause by hereditary conditions, certain medications, autoimmune diseases, or infections.

Causes of High HCT blood test

  1. Dehydration: One of the most common causes of a high HCT is dehydration. When the body loses fluids through inadequate water intake, excessive sweating, vomiting, or diarrhoea, the blood becomes more concentrated, leading to a higher proportion of red blood cells.
  2. Chronic hypoxia: Conditions that result in prolonged low oxygen levels in the blood can trigger increased RBC production to compensate for the lack of oxygen. This can happen in people with chronic Lung disease, for example, chronic obstructive pulmonary disease, emphysema, or pulmonary fibrosis.
  3. Smoking damages the lungs and reduces the oxygen available in the blood. In response, the body increases the production of red blood cells to increase oxygen-carrying capacity, leading to higher HCT.
  4. Polycythemia vera is a disorderly blood disorder characterise by abnormal overproduction of red blood cells by the bone marrow. It causes an elevated HCT blood test and is often accompanied by symptoms such as fatigue and an enlarged spleen.
  5. Living at high altitude: Living at high altitudes, where oxygen levels are lower, can stimulate the body to produce more red blood cells to reimburse for the reduced oxygen availability. This physiological response is known as altitude polycythemia or chronic mountain sickness.
  6. Kidney disease: Impaired kidney function can disrupt the normal regulation of erythropoietin (EPO), a hormone that stimulates RBC production. Reduced levels of EPO can lead to inadequate control of red blood cell production and result in higher HCT.

Treatment for High HCT levels 

  1. Treating dehydration: If dehydration is the cause of high HCT, the primary treatment is rehydration. Increasing fluid intake and restoring fluid balance can help normalise HCT levels. Drinking water and electrolyte-rich fluids are usually recommend.
  2. Treat the underlying condition: If a specific medical condition, such as polycythemia vera or chronic lung disease, is causing the high HCT, the focus is on managing and treating the underlying condition. This may include medication, lifestyle changes, or other appropriate interventions.
  3. Phlebotomy: Therapeutic phlebotomy may perform in polycythemia vera or other conditions where the body overproduces red blood cells. This involves removing a certain amount of blood from the body to decrease the amount of red blood cells and lower the HCT. This is usually under a doctor’s supervision and guidance.
  4. Oxygen therapy: If chronic hypoxia or lung disease is causing the high HCT, supplemental oxygen therapy may prescribe to increase oxygen levels in the blood. By ensuring adequate oxygenation, the body’s response to produce excess red blood cells may reduce, leading to a decrease in HCT levels.
  5. Medication: Certain medications may prescribe to treat the underlying condition contributing to the high HCT. For example, in polycythemia vera, drugs may suppress bone marrow activity or reduce the production of red blood cells.

Treatment for low HCT levels 

  1. Treat underlying conditions: If anaemia or other medical conditions are causing low HCT, the focus is on treating the underlying cause. This may include treating nutritional deficiencies (e.g., iron, vitamin B12, or folic acid supplementation), managing chronic conditions (e.g., kidney or liver disease), or stopping medications that may be causing the low HCT.
  2. Iron supplementation: Iron deficiency is a common cause of low HCT. Iron supplements may prescribe to increase iron levels in the body and advert red blood cell fabrication. The dosage and duration of iron supplementation depend on the weakness’s severity and the individual’s response.
  3. Blood transfusion: In severe cases of anaemia or acute blood loss, a blood transfusion may need to replenish red blood cells and increase HCT test levels quickly. This is usually reserved for cases where other treatments are insufficient or the situation is critical.
  4. Erythropoietin-stimulating agents (ESAs): In some instances, such as chronic kidney disease or chemotherapy-induced anaemia, ESAs may prescribe. These drugs encourage the bone marrow to produce more red blood cells, raising HCT test levels. ESAs are usually given under the supervision of a healthcare professional.
  5. Dietary changes: In cases where low HCT is caused by inadequate nutrient intake, adjusting the diet to include foods rich in iron, vitamin B12, and folate may help increase RBC production. A dietitian or healthcare professional can advise on appropriate dietary changes.

How is HCT blood test measure?

  1. Blood sample: A healthcare professional will take a small piece of blood from a vein in your arm using a needle and syringe or by pricking your finger.
  2. Laboratory analysis: The blood sample is sent to a laboratory and analysed using automated blood cell counters.
  3. Centrifugation: The blood sample place in a unique tube and centrifuged, which causes the blood components to separate according to their density. The red blood cells resolve in the backside of the box, forming a dense layer.
  4. Measurement: After centrifugation, the height of the pack red blood cells is measured and compared to the total volume of the blood sample. This measurement is shown as a percentage, which represents the hematocrit.
  5. Reporting: The hematocrit value and other CBC parameters are reported on a laboratory report or given To the health services expert who orders the test. The results regarding the individual’s overall health and medical history are then interpreted.

Normal ranges for HCT?

  1. Adult males: The normal range for adult males is usually around 38% to 50%. However, some laboratories may define the lower end of the content as 39% or 40%.
  2. Adult females: The normal range for adult females is typically 34% to 44%. Similarly, some laboratories may consider the lower end of the content to be 35% or 36%.
  3. It’s important to remember that these ranges are general guidelines and may vary slightly between different laboratories and healthcare providers. In addition, reference ranges may vary based on geographical location, ethnicity, and individual health conditions.
  4. If your HCT blood test is outside the normal range, it doesn’t necessarily mean you have a specific medical condition. HCT levels should interpret by a healthcare professional who will consider other factors such as the complete blood count (CBC) results, medical history, symptoms, and physical examination findings. They will thoroughly assess and decide whether further tests or treatment are need.
HCT blood test

What can High HCT levels mean?

  1. Dehydration: One of the most common causes of temporarily high HCT levels is dehydration. When the body becomes dehydrated, plasma volume decreases, leading to a relative increase in red blood cell concentration and an elevated HCT level.
  2. Lung or heart disease: Certain lung or heart conditions, such as chronic obstructive pulmonary disease (COPD), pulmonary fibrosis, congenital heart disease, or heart failure, can lead to low blood oxygen levels. In response, the body may produce more red blood cells to compensate for the reduced oxygen-carrying capacity, resulting in elevated HCT levels.
  3. Smoking: Smoking cigarettes can increase HCT levels due to the effect of carbon monoxide on oxygen delivery and red blood cell production.
  4. Kidney conditions: Some kidney diseases or conditions, such as polycystic kidney disease or renal cell carcinoma, can produce excessive amounts of erythropoietin (a hormone that stimulates red blood cell production), leading to increased red blood cell production and increased HCT levels.
  5. Polycythemia vera: Polycythemia vera is a rare bone marrow disorder characterise by the overproduction of red blood cells. It is a type of primary polycythemia and can lead to elevated HCT levels.
  6. High altitude: Living at high altitudes, where oxygen levels are lower, can stimulate the body to produce more red blood cells, resulting in higher HCT levels.
  7. Other factors: Other factors that may cause elevated HCT levels include certain medications (e.g., testosterone, erythropoietin-stimulating agents), smoking cessation, and certain genetic or acquired disorders that affect red blood cell production or function.

What can Low HCT levels mean?

  1. Anaemia: One of the most common causes of low HCT is anaemia. Anaemia occurs when there is a decrease in the number of red blood cells or the amount of haemoglobin in the blood. There are several causes of anaemia, including iron deficiency, vitamin B12 deficiency, folic acid deficiency, chronic diseases, and certain medications.
  2. Blood loss: Significant bleeding due to injury, surgery, gastrointestinal ulcers, heavy menstrual periods, or other sources of blood loss can lead to low HCT levels.
  3. Bone marrow disorders: ailments affecting the bone marrow’s ability to generate red blood cells can lead to low HCT. Examples include aplastic anaemia, myelodysplastic syndrome (MDS), and leukaemia.
  4. Nutritional deficiencies: Inadequate intake of essential nutrients, for example, iron, vitamin B12, or folic acid, can affect red blood cell productivity and cause low HCT levels.
  5. Chronic kidney disease: Kidney disease can affect erythropoietin production, a red blood cell production hormone. As a result, people with chronic kidney disease may have lower HCT levels.
  6. Chronic inflammatory diseases: Certain chronic inflammatory Diseases, for example, rheumatoid arthritis, lupus, and inflammatory bowel disease, can lead to low HCT levels.
  7. Hemolysis: Haemolysis is the premature destruction of red blood cells. Conditions that cause excessive destruction of red blood cells, such as autoimmune hemolytic anaemia or certain infections, can lead to low HCT.
  8. Pregnancy: During pregnancy, plasma volume increases more than the number of red blood cells, resulting in a relatively low HCT. However, a significant drop in HCT may indicate anaemia or other complications.


The Hct blood test, a fundamental component of a complete blood count (CBC), is crucial in assessing an individual’s overall health. The Hct test provides essential information about oxygen-carrying capacity, hydration levels, and potential underlying conditions by measuring the proportion of red blood cells in the blood. Doctors rely on Hct levels to diagnose conditions such as anaemia, polycythemia, and dehydration, guiding treatment decisions and monitoring health progress. Regular monitoring of Hct levels through this test is invaluable for maintaining well-being and addressing medical concerns promptly.

*Disclaimer: This article is for informational purposes only and should not substitute professional medical advice. Please consult a healthcare professional for a thorough evaluation of your symptoms and appropriate treatment.

Author Contribution: Reviewed by Dr. Ram Reddy, MD – General Physician, Rajeshwar Rao, Pharm D.

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