Blood count and blood group · Blood

Erythrocytes (red blood cells)

The number of red blood cells per liter of blood; together with hemoglobin and MCV the basis for assessing anemia.

At a glance

Measured in blood
In 12 test panels
No special preparation

Explanation

Erythrocytes (red blood cells): what is measured?

The analysis counts the number of red blood cells (erythrocytes) per liter of blood. Red blood cells are made in the bone marrow, live on average 120 days and contain the hemoglobin that carries oxygen. The number is always assessed together with hemoglobin, hematocrit and MCV: with iron deficiency the number of cells is often still normal while they are smaller and contain less hemoglobin, whereas in thalassemia carriers the number is actually relatively high.

What can it detect?

Anemia due to reduced production (shortage of iron, vitamin B12 or folic acid, chronic disease, bone marrow)
Loss or faster breakdown of red blood cells (bleeding, hemolysis)
Too many red blood cells (polycythemia) due to oxygen shortage, smoking, altitude or, rarely, a bone marrow disease

Result

What does the result mean?

Erythrocytes (red blood cells) too high

A slightly raised number of red blood cells is almost always a response to oxygen shortage or to thickening of the blood. The body makes extra cells with smoking, a lung disease, sleep apnea or a longer stay at high altitude; with dehydration, the same number of cells is in less fluid. Thalassemia carriers also often have many but small red blood cells with a normal or slightly low hemoglobin. Testosterone and anabolic substances increase production. A strongly raised number fits polycythemia vera, a rare bone marrow disease; the GP then refers to an internist or hematologist.

Erythrocytes (red blood cells) too low

A low number of red blood cells fits anemia. Causes are a shortage of building blocks (iron, vitamin B12, folic acid), a chronic disease or inflammation, a kidney disease, blood loss or faster breakdown of the cells. At the end of a pregnancy the number is often somewhat lower because the blood volume increases; this is normal. With a shortage of vitamin B12 or folic acid, the number of cells falls relatively sharply while the cells are large; with iron deficiency the number stays up for longer. Symptoms are tiredness, shortness of breath on exertion, dizziness and paleness.

After an abnormal result

The GP assesses the number of red blood cells together with hemoglobin, MCV and ferritin according to the Dutch GP guideline (NHG) on anemia and, if needed, has vitamin B12, folic acid, reticulocytes or tests for hemoglobin disorders done. With a persistently raised number without explanation, tests for oxygen shortage follow and, if needed, a referral to an internist or hematologist.

Reliability

How reliable is the test?

Counting red blood cells is automated and accurate. To diagnose anemia, the Dutch GP guideline (NHG) on anemia uses hemoglobin; the number of red blood cells is a supporting value that, mainly in combination with MCV and hemoglobin, says something about the cause. A normal number does not rule out iron deficiency, because with iron deficiency the number of cells stays normal for a long time.

What can affect the result?

Dehydration raises and dilution (pregnancy, drinking a lot, an IV drip) lowers the number per liter without the actual amount of cells changing.
Smoking, staying at altitude and testosterone use raise the number.
With a combined shortage of iron and vitamin B12, the effects can partly cancel each other out.
Reference values differ between men and women and between laboratories.

Who it is for

Who is the test useful for?

Useful for

Useful as part of the blood count with (suspected) anemia, in people from a risk group for thalassemia and for monitoring people who use testosterone or have a lung disease. Apart from hemoglobin and MCV, the number of red blood cells has little meaning.

How common is it?

In general practice, anemia is diagnosed in about 9 in 1,000 people per year, about four times as often in women as in men. An estimated 1 in 100 Dutch people is a carrier of thalassemia or another hemoglobin disorder; polycythemia vera is rare.

NHG guideline on anemia (M76)

Drawbacks and risks

A slightly abnormal number with a normal hemoglobin is usually harmless; on its own the value easily gives the wrong impression.

Get tested

Erythrocytes (red blood cells): test panels

Erythrocytes (red blood cells) is part of these test panels. You order online and have your blood drawn at a collection point or collect the sample at home.

Blood draw
Vegan Test
Panel for vegetarian or vegan diet; B12 D iron and more.
€ 116,00
Blood draw
General Health Checkup
With this General Health Check-up, you gain detailed insight into your overall health and well-being.
€ 125,00
Blood draw
Blood Count
Blood Count; complete analysis of blood cells for detection of anemia and infections.
€ 19,00
Blood draw
Complete Blood Count (CBC)
Complete Blood Count Extended; standard blood count plus detailed white blood cell analysis.
€ 27,00
Blood draw
InsideTracker
InsideTracker Blood Analysis: analyze 48 biomarkers for complete health optimization and personalized recommendations.
€ 335,00
Blood draw
Endurance Sports
Complete blood count, iron status (ferritin, transferrin), kidney function, liver function, testosterone, and hs-CRP. For athletes and endurance sport participants.
€ 203,00
Blood draw
Comprehensive Fatigue Test
Vitamin D, B12, TSH, fT4, glucose, MCV, ferritin, ESR and complete blood count. For persistent fatigue with inflammation check.
€ 152,00
Blood draw
Extended Cholesterol Test
Comprehensive cholesterol test with vitamin D, B12, and blood count. Combines heart health with a fatigue check in one package.
€ 98,00
Blood draw
Supplemental: Testosterone Replacement Therapy (TRT)
Complete hormonal analysis with testosterone, DHEA-S, thyroid, blood count, liver function, kidney function, lipids, glucose, HbA1c, insulin, hs-CRP, vitamin D and ferritin.
€ 335,00

How reliable is the test?

Erythrocytes (red blood cells)