At a Glance Why Get Tested? To determine the proportion of your
blood that is made up of red blood cells (RBCs), thus to screen
for, help diagnose, or monitor conditions that affect RBCs; as
part of a routine health examination or if your doctor suspects
that you have anemia or polycythemia When to Get Tested? With a
test for hemoglobin or as part of a complete blood count (CBC)
during a routine health exam or when your doctor suspects you
have a condition such as anemia (low hematocrit) or polycythemia
(high hematocrit); at regular intervals to monitor a disorder
that affects RBCs and to evaluate treatment effectiveness A
blood sample drawn from a vein in your arm or by a fingerstick
(children and adults) or heelstick (newborns) Test Preparation
Needed? The Test Sample What is being tested? Blood consists of
a few types of cells, including red blood cells (RBCs), white
blood cells (WBCs), and platelets, suspended in a fluid portion
called plasma. A hematocrit is a test that measures the
proportion of a perso