How Is Hemoglobin Converted to Hematocrit?

An article in the journal Tropical Medicine & International Health notes that the normal rule for hematocrit count is three times the hemoglobin count. The hematocrit value is a percentage, while hemoglobin count is in grams per deciliter. However, using this conversion factor can lead to inaccuracies in diagnosing anemia, especially in children, according to a study published in Tropical Medicine & International Health.

Traditionally, medical personnel use either of these two numbers to determine anemia. Of the two, the hematocrit value requires less specialized equipment and is the quicker option, according to "Clinical Methods: The History, Physical, and Laboratory Examinations." It requires a finger stick with blood drawn into a capillary tube. Medical personnel spin the sample in a centrifuge to separate it into layers. They then measure the length of the column of red blood cells and the total volume. The hematocrit is the ration of these two numbers multiplied by 100.

Hospital laboratories determine hemoglobin counts using automated equipment. The test requires a specific amount of blood and the addition of reagents to convert hemoglobin to a colored protein. The machine compares the light passing through the tube at a specific wavelength to a standard using a device scientists call a colorimeter, according to "Clinical Methods."