Red Blood Cells

Disclaimer: Information on this page is for educational purposes. Consult a physician to interpret your test results. Lissa Health helps track biomarker trends but does not replace medical advice.

What This Test Measures

Red blood cells (erythrocytes) carry oxygen from the lungs to tissues via hemoglobin. Their count is a fundamental measure of the blood's oxygen-carrying capacity.

Low RBC count (erythropenia) occurs in various anemias, while elevation is seen in polycythemia, dehydration, and chronic hypoxia. This marker is evaluated alongside hemoglobin, hematocrit, and red cell indices.

Changes in RBC count may develop gradually, making trend monitoring important during iron, vitamin, or erythropoietin therapy.

Normal Ranges

Group	Reference Range
Men	4.0–5.5 × 10¹²/L
Women	3.8–5.0 × 10¹²/L
Children	3.5–5.5 × 10¹²/L (age-dependent)

Reference ranges may vary by laboratory and assay method.

Causes of High Levels

• Dehydration (relative erythrocytosis)
• Polycythemia vera
• Chronic hypoxia (COPD, smoking, high altitude)
• Erythropoietin-producing renal tumors
• Corticosteroids and anabolic steroids

Causes of Low Levels

• Iron, B12, and folate deficiency anemia
• Chronic kidney disease
• Aplastic anemia and bone marrow suppression
• Hemolysis (autoimmune, hereditary)
• Acute and chronic blood loss

Test Preparation

• No special preparation required
• Avoid dehydration and strenuous exercise beforehand
• Report menstrual blood loss and chronic conditions

Related Biomarkers

Biomarker	Relationship
Hemoglobin	Oxygen-carrying protein content
Hematocrit	Proportion of blood volume occupied by RBCs
Mean Corpuscular Volume (MCV)	Mean red cell volume

FAQ

How often should I take this test?

Annually for routine checkups; with anemia — every 4–8 weeks to monitor treatment.

What should I do if my result is abnormal?

If abnormal, your doctor will order iron studies, B12, folate, reticulocytes, and other tests to determine the cause.

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Last updated: June 2026