Red Blood Cell Per Cent (RBC Percentage)

This test measures the percentage of red blood cells (RBCs) in your blood. Red blood cells carry oxygen from your lungs to every part of your body, and this measurement helps show whether your blood is able to deliver enough oxygen to keep you healthy.

The RBC percentage is calculated by comparing the volume of red blood cells to the total blood volume. This ratio can help identify whether your red blood cells are too few, too large, or too small, which may indicate different types of anemia or other blood disorders.

Your doctor may order this test as part of a routine checkup or to help investigate symptoms such as fatigue, weakness, dizziness, shortness of breath, or unusual paleness. It can also be used to monitor a known blood condition or to track how well a treatment is working over time.

Doctors may order RBC percentage tests when they suspect anemia, evaluate blood disorders like polycythemia (too many red blood cells), or monitor conditions that affect red blood cell production or survival, such as kidney disease or certain cancers.

Common reasons for testing include suspected anemia, nutritional deficiencies such as low iron or vitamin B12, chronic conditions like kidney disease, signs of dehydration, or ongoing symptoms that suggest your red blood cell levels may be too high or too low.

Symptoms like fatigue, pale skin, dizziness, or unusual bleeding might prompt this test. It’s also part of routine blood checks or follow-ups for chronic illnesses.

A small blood sample is usually drawn from a vein in your arm, and the procedure takes only a few minutes. In most cases no special preparation is needed, but follow any instructions from your provider, such as whether you should fast or avoid certain medications beforehand.

This test uses a simple blood draw from a vein in your arm. No special preparation is needed, but fasting may not be required unless specified by your doctor.