Devices intended to determine the blood’s hematocrit-the ratio of red-cell volume to whole blood volume, expressed as a decimal, a fraction, or a percentage. Microhematocrit centrifuges may be used to help diagnose blood loss, polycythemia (an elevation of the erythrocyte count to above-normal levels), anemia, bone marrow failure, leukemia, and multiple myeloma. High hematocrit levels indicate dehydration and erythrocytosis.