Reticulocytes, or immature red blood cells, can tell you how well your bone marrow is working. They can help zero in on underlying health issues or tell if certain therapies are working. Keep reading to learn more about high and low reticulocyte counts and their effects on your health.

What are Reticulocytes?

Reticulocytes are newly formed immature red blood cells. They are produced in the bone marrow [1].

Normally, doctors use a reticulocyte test to look at bone marrow function. That’s because reticulocytes are a good indicator of your ability to produce red blood cells. You might get this test if you have low red blood cell count, low hemoglobin, or low hematocrit [1, 2].

Because there are many diseases and conditions that can affect red blood cell production and bone marrow function, a reticulocyte test can indicate something may be wrong but it cannot be used to diagnose a particular disease on its own [1, 2].

Your doctor may also use the reticulocyte count to check how bone marrow or your kidneys respond to particular therapies [3].

Normal Range

Normally, reticulocytes make 0.5 – 1.5 % of your red blood cells (up to 2.6% according to some laboratories). The values are higher in infants, ranging from 2 – 6%.

Absolute reticulocyte counts normally range from 20 – 80 thousand cells/uL (cells per microliter).

Low Reticulocyte Count

Causes of Low Reticulocytes

1) Abnormal Bone Marrow Function

Decreased reticulocyte count (medically known as reticulocytopenia), can be a result of abnormal or suppressed bone marrow function. Bone marrow issues can be caused by infection, injury, or cancer [1].

In addition, bone marrow function can be decreased as a result of cancer therapy [1, 4].

2) Anemia

Low reticulocyte count can be an indicator of various anemias (e.g. iron deficiency anemia and aplastic anemia) [1, 5].

Nutrient deficiencies that cause anemia, such as iron, folate, or vitamin B12 deficiency can decrease your reticulocyte count [6, 7, 1].

3) Alcoholism

Alcoholism and alcohol abuse can decrease reticulocyte count [8, 1].

4) Viral infections

Viral infections can cause your reticulocyte count to temporarily decrease [9].

5) Kidney Disease

Erythropoietin is a hormone made in the kidneys that travels to the bone marrow where it stimulates the production of red blood cells.

In kidney disease, the production of erythropoietin decreases, which reduces the red blood cell production. That is why kidney disease can be linked to a decreased reticulocyte count [10, 11].

Ways to Increase Reticulocytes

Eat a Balanced Diet

Make sure you are not deficient in nutrients needed to produce red blood cells, such as iron, folate, and vitamin B12 [1].

Stop Drinking Alcohol

Since excess alcohol consumption can cause decreased reticulocyte counts, reducing or eliminating alcohol from your lifestyle can help improve your reticulocyte counts [8, 1].

High Reticulocyte Count

Causes of High Reticulocytes

1) Hemolysis

A high reticulocyte count (medically known as reticulocytosis) may mean there is hemolysis or increased red blood cell destruction. When there aren’t enough red blood cells in the body, the body tries to increase red blood cell production. However, the bone marrow can release these cells before they have fully matured, which increases reticulocyte levels in the blood [1, 12].

For example, increased hemolysis and reticulocyte counts occur in sickle cell disease [1, 13].

2) Endurance Exercise

Athletes may have increased reticulocytes due to exercise. Exercise increases cortisol and other stress hormones, which in turn stimulate reticulocyte release from the bone marrow [14, 15].

3) Blood Loss

Bone marrow will compensate for blood loss by increasing red blood cell production. This will result in higher reticulocytes short-term. They will eventually decrease back to normal [1].

3) Toxins

Exposure to toxins such as ethylene glycol ethers, common ingredients in paints and cleaners, can increase reticulocyte counts. In an observational study of 34 screen-printing workers, the people who were exposed to the toxins had significantly higher reticulocyte counts [16].

Lead is another toxin that can increase reticulocytes [17].

Smoking can also increase reticulocyte counts [18].

4) Pregnancy

Reticulocyte counts can be normally increased in pregnancy [19].

5) Overproduction of Red Blood Cells

Polycythemia vera is a condition in which there is higher red blood cell production. It is linked to higher reticulocyte counts [20].

Erythroid leukemia, a rare form of acute myeloid leukemia, causes higher reticulocyte production and release [21].

Reticulocytes can also increase in erythropoietin therapy or doping [22, 23].

Health Effects of High Reticulocytes

1) Risk of Stroke

In sickle cell disease patients, reticulocyte count is a predictor of stroke. In various observational studies, patients with a high reticulocyte count had a higher risk of stroke [24, 25, 26, 27].

2) Risk of Death

In an observational study of 386 liver transplant candidates, a high reticulocyte count was associated with an increased risk of death [28].

High reticulocytes are also associated with death in sickle cell disease patients [29, 30].

Ways to Decrease Reticulocytes

Quit Smoking

Stop smoking – this can prevent your reticulocytes from being elevated [18].

Magnesium Supplementation

In sickle cell disease patients, magnesium supplements significantly reduced reticulocyte counts [31].

Irregular Reticulocyte Levels?

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