Hematocrit Blood Test: Low or High Hct Levels Meaning

If you show symptoms of anemia (low blood count), irritation, dizziness, constant headaches, and heavy periods, your doctor might want to carry out a blood test. A hematocrit test is a blood test that medical professionals undertake to diagnose health conditions like anemia and other related issues. The hematocrit test allows medical practitioners to make the correct diagnosis and recommend the proper treatment.

The present article highlights and describes hematocrit tests and what low hct and high hct mean.

Hematocrit (hct) Blood Test
Hematocrit (hct) Blood Test

What is hematocrit?

Hematocrit (hct) is a measurement of the volume percentage (size and number) of RBCs (red blood cells) that someone has. The hematocrit test is carried out by volume but is usually expressed in percentage. For example, if an individual has a hct of 35%, he or she has 35 milliliters of RBCs in 100 milliliters of blood.

Medical practitioners will ask a person (he or she) to get a hct test as part of a complete blood count (CBC) to determine how well the person responds to a particular treatment or to determine and diagnose if he or she has any underlying health issue. It helps assess the hemoglobin (Hgb) present in RBCs that carry oxygen. Hemoglobin is essential for the body to function correctly (Billett,1990).

Why is hematocrit important?

Hct tests are essential as they help to measure the blood count (RBCs). If a person is experiencing fatigue, cold feet and hands, poor focus, heavy periods, and irritation, he could be anemic. To diagnose this condition, medical practitioners use hematocrit tests.

Hct tests are called PCV (packed cell volume) tests.  Hct tests also help determine if the person has nutritional deficiencies or other critical medical conditions like arthritis, leukemia, or renal issues. Too low or too high an RBC count indicates certain diseases or nutritional deficiencies that medical practitioners will know how to identify (Rieder et al., 2014).

What to expect during a hematocrit test?

During a hct test, a phlebotomist will take your blood sample for testing purposes. The blood drawing process can be a little unpleasant and uncomfortable for some.  Some also feel a feeling of light-headedness. So, lying down while the blood sample is being taken is advisable.

What is an average hematocrit level?

35% – 50% hematocrit level is considered normal in the case of a healthy adult. In the case of women, a hematocrit level between 36.1% – 44.3% (36% to 44% red blood cells) is considered normal, and in the case of men, a hematocrit level range between 40.7% – 50.3% (40% to 50%) is considered normal. A hematocrit level between 32% – 61% is average (Cohen et al., 2017).

Hct tests are very reliable and usually pretty accurate for monitoring anemia. These tests aid medical practitioners in diagnosing the proper medical condition and advise the most suitable treatment. Some factors that are responsible for giving wrong and inaccurate (abnormally low or high) hematocrit levels include:

  • Blood transfusions (the process of transferring blood products into one’s circulation intravenously) that have taken place recently
  • Hct levels are usually lower than usual when women are pregnant
  • Hct levels are generally higher than normal for people living at a high altitude
  • High hct levels are also caused by dehydration

Health practitioners very well know what factors could potentially skew hct test results. If some health conditions affect your hct results, your doctor might ask you to retake the test at a different time.

What does it mean if your hematocrit is low?

Low hct levels are referred to as a condition of anemia. If you’re experiencing any of the below-listed signs, they could mean you have a low red blood cell count:

  • Fatigue
  • Headaches
  • Absence of focus
  • Heavy monthly periods
  • Irritation and being grumpy
  • Shortness of breath

If you take a hct test, and the results show that the hct levels are low, you have anemia, and your red blood cells are in a lower percentage (Reinhart, 2016).

What causes low hematocrit (HCT) Levels?

Several causes of low hematocrit include;


Low hematocrit levels are indicative of the person being anemic. Ascertaining to HCT and testing Hgb levels (hemoglobin levels) can help determine how much anemic (low blood levels) a person is. Low hematocrit levels and other Red Blood Cells indices can also help establish the reasons for the development of anemia (Miller, 2013).

Other symptoms of anemia can include:

  • Tiredness and less energy
  • Erratic or a racing heartbeat
  • Difficulty breathing or shortness of breath
  • A pale complexion

Nutritional deficiencies

Low HCT levels are indicative of nutritional deficiencies that are associated with anemia. It can indicate low vitamin B12 (cobalamin) and folic acid (a water-soluble B vitamin).

Low levels of these nutrients are often accompanied by too little iron in the body (iron deficiency). Many people have B-group vitamin deficiencies.

These vitamins are – thiamin (B1), riboflavin (B2), niacin (B3), pantothenic acid (B5), pyridoxine (B6), biotin (B7), and folate. As well as displaying symptoms of anemia, signs of a B12 deficiency (Cobalamin deficiency) can also include:

  • Irregular or disturbed sleep patterns
  • Mood swings
  • Problem indigestion
  • Headaches
  • Difficulty in focus and concentrating

(Chaparro & Suchdev, 2019).


People with rheumatoid arthritis (an autoimmune disease that causes joint pain and damage to the joints) may also have low hematocrit and inadequate oxygen-rich blood cells.

Several scientific studies have reported that low Hgb levels (hemoglobin levels) in the blood are connected with the severity of the illness. Low hematocrit levels in people with rheumatoid arthritis can also result in other severe conditions (Smirnova, 2014).


People with low hematocrit levels can also show depression, elevated stress, and panic disorder symptoms. Anxiety and panic disorder elevate inflammatory responses in the system.

This triggers a reduction in hematocrit levels. Medical experts have also reported that the blood test results from stressed and anxious people show an increase in neutrophils (a type of white blood cell that helps heal damaged tissues) and leukocytes (WBCs) (Mathew & Wilson, 1987).

Turmeric supplements are beneficial in treating depression to a great extent. Apart from these supplements, 5-Hydroxytryptophan, also known as oxitriptan (a naturally occurring amino acid), and S‐adenosyl methionine (SAMe) supplements help to deal with symptoms of depression.


Hematocrit levels are lower than usual in people suffering from chronic fibromyalgia pain. Inflammation in the body impacts RBCs and WBCs production. Anxiety and elevated sexual dysfunction are some health disorders associated with fibromyalgia.

Several studies have proved that people with fibromyalgia have low hemoglobin and hematocrit levels. D-Ribose supplements (a critically important sugar molecule that helps improve health and exercise performance) help address fibromyalgia symptoms (Bellato et al., 2012).

Kidney disease

There is a significant reduction in hematocrit levels in people who suffer from kidney disease. RBC (Red Blood Cell) production is affected by kidney illness as the secretion of kidney hormones controls the RBCs.

People suffering from chronic kidney disease (CKD) or renal disorders usually have lower than the normal range of HCT levels and Hgb (hemoglobin levels). To keep kidneys healthy and functioning correctly, and prevent infection, drink plenty of water, avoid excess sugar, alcohol, smoking, and a sedentary lifestyle (Mehdi & Toto, 2009).

Digestive problems

Low HCT levels indicate inflammation in the digestive tract that affects RBC volume. A form of the digestive issue called ulcerative colitis (inflammatory bowel sickness) can affect HCT levels.

People suffering from digestive issues and autoimmune conditions (in which the body’s natural defense system is weak and attacks the normal cells) exhibit signs of anemia.

The reason is excessive internal bleeding in the digestive system. Crohn’s disease and ulcerative colitis are just 2 reasons your digestive system doesn’t work correctly (Al-Laham et al., 2015).

Other signs of inflammatory digestive conditions include:

  • Frequent bouts of diarrhea after eating
  • Passing greasy stools
  • Pain under your ribs
  • Indigestion and heartburn

Autoimmune conditions

Low Hct is often associated with certain autoimmune conditions, and checking hematocrit levels can help doctors recommend the best course of treatment. Some research studies report that some autoimmune conditions can result in anemia. Low mean platelet volume (MPV) in a lab blood test can also be used to identify some autoimmune diseases (Giannouli et al., 2006).

Low Hematocrit Symptoms

Doctors often arrange for an Hct test if a person complains of symptoms associated with a low hematocrit. A drop in Hct levels could be that red blood cells are getting destroyed quicker than the body can make them, or the body isn’t creating enough of them.

Symptoms of low hematocrit include the following;

  • Shortness of breath
  • Feelings of dizziness or light-headedness
  • Frequent headaches
  • Chest pain
  • Clammy skin that looks pale
  • Tiredness
  • Lack of concentration
  • Shortness of breath
  • Headaches
  • Heavy menstrual cycles
  • Grumpiness

(Kishimoto et al., 2020).

What to do for abnormally low hematocrit levels?

Doctors advise blood transfusions or intravenous blood if the tests show deficient RBCs. In some cases, if the body cannot make RBCs due to an existing or underlying health condition, the doctor might prescribe some medication to help stimulate new RBCs. A healthy diet rich in all essential nutrients, vitamins, and folic acid is also beneficial in preventing anemia.

Just because you have low hct levels does not necessarily mean you suffer from the above medical complications. Your health practitioner will perform another medical diagnosis through further tests to help ascertain and determine what’s going on (Goodnough & Schrier, 2014).

What does it mean if your hematocrit is high?

Anyone experiencing the below-listed symptoms is indicative of hematocrit being higher than usual. In case of any of these signs and symptoms, you should consider your doctor about whether or not an hct test is needed for you. These symptoms include;

  • Flushed skin
  • Fatigue
  • Dizziness
  • Shortness of breath
  • Headaches
  • Itching
  • Pain in the joints
  • Sweating

High hct levels mean your RBCs are abnormally high and could be indicative of the below given medical conditions:

  • Erythrocytosis (a condition in which your body makes too many red blood cells (RBCs))
  • Dehydration
  • Carbon monoxide poisoning (when carbon monoxide builds up in your bloodstream)
  • Congenital heart disease (an abnormality in the heart that happens before birth)
  • Bone marrow disease (polycythemia vera)
  • Posterior reversible encephalopathy syndrome (for example, from high blood pressure)
  • COPD (chronic obstructive pulmonary disease) exacerbation
  • Retinopathy (eye blood vessel damage)
  • Pulmonary fibrosis (scarring of the lungs) and pulmonary hypertension
  • Less oxygen in the blood (often due to lung conditions)
  • Sleep apnea
  • Capillary leak syndrome (leaky blood vessels)
  • Cystic fibrosis
  • Eclampsia (pregnancy complications)
  • Hyponatremia (low blood sodium)
  • Metabolic syndrome
  • Necrotizing pancreatitis (for example, from alcohol abuse)
  • Ovarian hyperstimulation syndrome (for example., from fertility treatments)
  • Prediabetes

Abnormally high hct levels of RBCs do not warrant that you are suffering from any of the above-listed health conditions. Your health practitioner will diagnose the reasons for your high hct levels and whether or not you have any of the above medical conditions.

What Causes high hematocrit (HCT) Levels?

A high hematocrit level happens when the body needs increased oxygen because;

  • You live at a high altitude, and your RBC production naturally increases to compensate for the lower oxygen supply there.
  • Spaceflight
  • Workplace pollution
  • Your sleeping position (head tilted downward)
  • Being male
  • Being obese
  • Depression
  • Army/Military training
  • You are a smoker

(Mondal & Budh, 2020).

High hct levels are less common because

  • Your RBC production increases to compensate for deficient blood oxygen levels because of improper lung and heart functioning.
  • The bone marrow is forming too many RBCs
  • You are on drugs like erythropoietin (EPO) that stimulate RBC production

What to do for abnormally high hematocrit levels?

Some lifestyle changes like quitting cigarette smoking and remaining hydrated help lower abnormally high hematocrit levels. Some medications, like aspirin, are also prescribed to prevent the formation of blood clots due to increased red blood cells.

Other medicines that health practitioners may prescribe for high medications that doctors prescribe for high red blood cells are likely to emphasize treating medical conditions responsible for producing too many red blood cells, like bone marrow or heart disease.

Bloodletting (Phlebotomy) is a common technique to reduce abnormally high red blood cell counts. In this procedure, the blood is withdrawn from the veins to make them thinner.

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