Primus Pathology Laboratory

Hematocrit Test

Last Updated on August 1, 2022 by Dr. Neeraj Gujar

Hematocrit test Overview

A blood test called a hematocrit measures the number of red blood cells in your blood. The oxygen carried by red blood cells from your lungs to your body is known as the hematocrit. Other parts of your blood are white blood cells (to fight infection), platelets (to make blood clots and stop bleeding), as well as a liquid called plasma.

A high or low hemoglobin level could indicate a blood disorder or dehydration or any other medical condition that can affect your blood.

What’s Hematocrit?

Hematocrit refers to the percent of red blood cells within the total blood volume. Your health is dependent on red blood cells. They are the subway system for your blood. They carry oxygen and nutrients to different parts of your body. Your body must have enough red blood cells to keep you healthy.

If your doctor is concerned about your hematocrit (Hct), they may order a test to determine if there are too many or too few red blood cells.

Why Test Is Done?

A hematocrit test may be ordered by your doctor as part of your routine checkup. It can also be used to monitor your health if you are currently being treated for a disease or have ongoing health conditions. If you are experiencing symptoms such as anemia, polycythemia, or another red blood cell disorder (such as anemia), your provider may order the test.

Anemia is a condition where there are too few red blood cells.

  • Breathing problems
  • Dizziness
  • Weakness or fatigue
  • Headache
  • Arrhythmia (problems with your heartbeat’s rhythm or rate)

Polycythemia, which is characterized by too many red blood cells, may be accompanied by the following symptoms:

  • Headache
  • Breathing difficulties
  • Fatigue or weakness
  • Feeling dizzy or lightheaded
  • Itching after a bath or shower, burning, or redness are all signs of skin conditions.
  • Heavy sweating during sleep
  • Bleeding gums or heavy bleeding from small cuts
  • Blind spots and blurred vision

When to get Tested?

A hematocrit test does not require any preparations. Your doctor may ask you to fast if other additional tests as prescribed. If there are any additional instructions, your provider will inform you.

How To Get Tested?

A hematocrit test does not require any preparations. Your doctor may ask you to fast if other additional tests as prescribed. If there are any additional instructions, your provider will inform you.

During the Test

A small needle is used by a health professional to take blood from a vein on your arm. Once the needle has been inserted, some blood will be taken and stored in a vial or test tube. The needle may cause a slight stinging sensation when it is inserted or removed. It usually takes less than five minutes.

After The Test

A hematocrit or other blood test is not a risky procedure. Although you may feel a little bit of pain or bruise around the site where the needle was inserted, most symptoms disappear quickly.

There are no major side effects associated with a hematocrit test. There may be some bleeding or throbbing around the site of the blood draw. If you notice swelling or bleeding, let your doctor know.

hematocrit test

Illustration of a nurse holding the blood sample collected for hematocrit testing

Also Read: Red Blood Cell (RBC) Count

Test Results

The number indicates the percentage of blood made up of red blood cells. If your hematocrit is 42, this means that 42% of blood is made up of red blood cells. The rest are white blood cells, platelets, and blood plasma.

Although each laboratory may have its ranges, the generally accepted ranges of hematocrit are determined by your gender and your age. The following ranges are typical:

  • Adult men: 38.8 to 50 Percent
  • Adult women: 34.9 to 44.5 Percent

Children aged 15 and under have their ranges as their hematocrit levels can change quickly with age. The normal hematocrit range of a child at a given age will be determined by the lab that analyses the results.

It can indicate a variety of problems if your hematocrit levels fall too low or high.

Interpreting Results

A lower hematocrit than the normal could indicate:

  • Anemia is a condition in which your body does not have enough red blood cells (anemia). Different medical conditions can cause anemia in different ways.
  • You may have too much white blood cell production, which indicates –
    • Bone marrow diseases
    • Some cancers include leukemia and lymphoma. Other cancers are multiple myeloma or cancers that spread from other parts of the bone marrow.

An elevated hematocrit may indicate:

  • The body may be producing too many red blood cells, which could be due to:
    • Lung disease
    • Heart failure
    • Congenital Heart Disease
    • Polycythemia
  • Low blood plasma levels due to:
    • Dehydration
    • Shock

It doesn’t necessarily mean you have a medical condition. High hematocrit may be caused by living at higher altitudes with less oxygen. This is because your body reacts to low oxygen levels by producing more red blood cells, so you can get the oxygen you require.

Low hematocrit can occur during pregnancy. This is because your body contains more fluid during pregnancy than usual, which reduces the number of red blood cells.

Talk to your provider to find out what your test results mean.

What happens if my hematocrit is too low?

Low hematocrit levels could be an indication of:

  • Chronic inflammatory disease
  • Bone marrow diseases
  • Vitamin B-12 is required to correct deficiencies in nutrients like iron, Folate, and vitamin B-12
  • Internal bleeding
  • Kidney disease
  • Hemolytic anemia
  • Lymphoma
  • Leukemia
  • Anemia due to sickle cell disease

What happens if my hematocrit is too high?

A high hematocrit level can indicate:

  • Congenital cardiac disease
  • Kidney tumor
  • Lung diseases
  • Dehydration
  • Polycythemia vera

Also Read: Hemoglobin Test


What medications affect hematocrit?

Drugs that can affect hematocrit levels are Cephalosporins (a class of antibiotics), Levodopa, Dapsone, Levofloxacin, Nitrofurantoin, Nonsteroidal anti-inflammatory drugs (NSAIDs), Methyldopa, and Penicillin and its derivatives.

How do you treat high hematocrit?

The most common treatment for polycythemia is frequent blood withdrawals known as phlebotomy. It is the same procedure used for donating blood. This decreases your blood volume and reduces the number of excess blood cells.

Can exercise lower hematocrit?

Those who are trained in endurance sports have seen a decreased hematocrit, which is also known as sports anemia. But it is not anemia in a clinical sense. This is because athletes have an increased total mass of red blood cells and hemoglobin in circulation relative to the sedentary individuals.


by Dr. Neeraj Gujar

Dr. Neeraj Gujar has done his M.D. in Pathology from Government Medical College. He has worked at various organisations such as Breach Candy Hospital and Tata Memorial Hospital along with many other private organisations. During his working career, he realised the pressing need for exceptional quality diagnostic services. A diagnostic centre that can consistently give accurate results verified by a consultant doctor (M.D. Pathologist) on which your doctor can depend. This has been the founding principle of Primus Pathology and Diagnostics.

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