HCT Blood Test: Normal, Low, and High Hematocrit Levels

An HCT blood test is a routine blood test. It usually is included if a patient is asked to have a complete blood count (CBC). Results can help doctors refine their diagnosis.

Drawn blood in test tubes

An HCT blood test is a routine blood test. It usually is included if a patient is asked to have a complete blood count (CBC). Results can help doctors refine their diagnosis. Read on for more details about the HCT blood test and what normal, low, and high hematocrit levels mean.

What It Is

What is a hematocrit test? Knowing the answer to this question is essential in understanding what an HCT blood test is for. Quick review: the blood has three components — platelets, white blood cells, and red blood cells.

  • Platelets are the cells in your blood that take care of damaged vessels. Once injury is detected, platelets do their job by zeroing in on the location of the damage and then causing a clot to stop the bleeding.
  • Also known as leukocytes, white blood cells (WBCs) defend our body from infections, diseases, and other foreign invaders.
  • Red blood cells (RBCs) carries oxygen throughout the body. They also are vehicles by which carbon dioxide is expelled through the lungs.

So what does the HCT blood test target? It actually focuses on the RBCs. It shows how much of your blood is made up RBCs. The target is to have an RBCs count that is within the normal range. For men, it should be around 45% to 52%. For women, it should reach at least 37% to 48%. If you fall within the range that is too high or too low, it could be indicative of underlying health concerns that need immediate medical intervention.

How It Is Done

As mentioned earlier, an HCT blood test is usually included in a CBC so it follows the same procedure:

  • Blood sample is drawn from a patient.
  • Sample is analyzed by an automated machine or a centrifuge.
  • RBCs volume is identified.

As you can notice, it is a quick and straightforward test that does not require too much. Patients do not even have to fast. However, you might still want to consult your doctor if he/she will require you to do added preparation before submitting yourself to this test. It would ultimately depend on your health status and other factors your physician has to consider.

Why Take It

There could be varied reasons why your doctor would prescribe an HCT blood test for you. Here are the most probable reasons:

  • Make an accurate diagnosis of a suspected disease or infection that the patient may have.
  • Rule out other conditions that have similar symptoms.
  • Monitor patient’s response to certain medication or treatment.
  • It could just be part of a person’s routine medical test.


So what does it mean if the HCT blood test shows high hematocrit levels or low hematocrit levels? Here is a picture of what it could possibly indicate:

High hematocrit level

  • Chronic smokers are known to register high in an HCT blood test. Since high hematocrit levels can lead to serious health concerns, it would be best to quit smoking as soon as possible.
  • Lung disease is yet another problem if there is sustained hematocrit level that is too high compared to the normal range. This could mean shortness of breath and pneumonia. If not treated right away, this might trigger fatal respiratory failure.
  • Congenital heart disease could also be indicated by high hematocrit level as identified by an HCT blood test. This disease is an anomaly in the heart’s structure. This is a serious condition that needs corrective surgery as soon as possible.
  • Dehydration could also be another indication of high hematocrit level. Drinking enough water daily can reverse this problem.
  • Polycythemia vera happens when the bone marrow abnormally produces too many RBCs. This is the reason why there is a high hematocrit level. Untreated, this condition may be fatal. Unfortunately, this cannot be reversed. However, patients with polycythemia vera can successfully live with this condition if symptoms are properly treated and monitored.

Low hematocrit level

  • Anemia is one of the more common indications if there is low hematocrit level. This happens when there is low RBC count.
  • Kidney disease could also be another indication of low hematocrit level. You should exhibit other symptoms of kidney disease apart from low hematocrit level for the doctor to diagnose that this is the condition that you are suffering from.
  • Deficiency in vitamins and minerals could cause low hematocrit level. You might need to have iron or Vitamin B supplements to correct this problem.
  • Multiple myeloma, lymphoma, and leukemia could be causing low hematocrit level. These are serious forms of cancer that need accurate diagnosis and immediate treatment. They can be aggressive if not monitored and treated immediately.
  • Bone marrow disease that causes the bone marrow to stop producing RBCs. While this cannot be reversed, condition can be treated with blood transfusion, medication, and stem cell therapy.

Normal hematocrit level

There are certain factors that can cause hematocrit levels to go up and down. These factors could include age, gender, pregnancy, even the altitude of your current location. Here are the normal hematocrit levels as ascertained by an HCT Blood Test. These would vary according to age.

  • Infants: At least 55% and not more than 68%
  • One week old: At least 47% and not more than 65%
  • One month old: At least 37% to 49%
  • Three months old: At least 30% to 36%
  • One year old: At least 29% to 41%
  • Ten years old: At least 36% to 40%
  • Adult Males: At least 45% to 52%
  • Adult Females: At least 37% to 48%

Having too high or too low hematocrit levels is not a death sentence. What you should do is to listen to your physician and with him or her, chart a plan for proper monitoring and treatment. Once you can do that, you can still live a good life despite the condition or illness that you have to live with. A routine HCT blood test can definitely help you since early detection matters. Patients are encouraged to undergo it at least once or twice a year even without exhibiting certain symptoms.

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