White blood cells fight infection. Red blood cells and hemoglobin carry oxygen. If your red cell count falls too low, your heart must work harder to deliver oxygen throughout your body. The hematocrit, mean cell hemoglobin, and mean cell hemoglobin concentration are various ways we measure your red cell count. If your red blood cells or hemoglobin are very low, you may feel tired or become short of breath.
Platelets stick together to stop bleeding.
If your platelet count is low, a cut may bleed longer than is normal. These terms describe whether your counts are higher or lower than the normal range for a specific blood test. A high or low blood count has different significance for each individual, depending on his or her health. A normal range for a lab test is based on the test results of a very large number of people. The test results of most, but not all, patients will fall into this normal range.