The Full form of RBC is Red Blood Cells. RBCs are the cells in human body that carry oxygen and carbon dioxide through the blood. This is due to the presence of hemoglobin, the pigment that makes red cells (and blood) look red. The red blood cells are also known as erythrocytes or red corpuscles (literally, red hollow vessels). A RBC count is a blood test that the doctor uses to find out how many RBCs (red blood cells) you have. It’s also known as an Erythrocyte count. The test is important because RBCs contain hemoglobin, which carries oxygen to the body’s tissues. The number of RBCs you have can affect how much oxygen your tissues receive. Your tissues need oxygen to function. If RBC count is too low or too high, one could experience symptoms and complications. If a person has a low RBC count, symptoms could include: fatigue, shortness of breath, weakness, dizziness, or lightheadedness, particularly when you change positions quickly, increased heart rate, headaches and pale skin. Whereas, if a person has a high RBC count, he could experience symptoms such as: fatigue, shortness of breath, joint pain, tenderness in the palms of the hands or soles of the feet, itching skin, particularly after a shower or bath, or sleep disturbance.