What is a complete blood count?
A complete blood count (CBC), one of the most common blood tests performed, may be ordered as part of a routine medical examination. In a CBC, the various types of blood cell are analyzed, using 6 different tests: Red Blood Cell Count (RBC)
White Blood Cell Count (WBC)
Differential Blood Count (Diff)
What is a red blood cell count?
Red cells, the most common type of blood cell, are responsible for transporting oxygen throughout the body. A red blood cell count (RBC) is ordered to check whether the number of red cells in the blood is abnormally high or abnormally low.
The ranges for a normal red blood cell count are:
Adult females: 4.2 to 5.4 million red cells per microliter (uL, a millionth of a liter) of blood Adult males: 4.7 to 6.1 million/uL Abnormal RBC may indicate: Anemia (low RBC)
Polycythemia (high RBC)
What is a hematocrit?
The hematocrit test, like the RBC, is performed to check whether the red cell count is abnormally high or low.
In the hematocrit test:
The patient's finger is pricked.
A drop of blood is drawn into a vary narrow glass tube.
The tube is spun at high speed (in a centrifuge).
The dense red blood cells pack down to the bottom of the tube, leaving the liquid portion of the blood at the top of the tube. The fraction of the tube occupied by the packed red blood cells represents the fraction of red cells in the blood.
The ranges for a normal hematocrit are:
Females: 0.37 to 0.47 (37% to 47% of blood volume occupied by red cells) Males: 0.42 to 0.52
Like an abnormal RBC, an abnormal hematocrit may indicate:
Anemia (low hematocrit)
Polycythemia (high hematocrit)
What is hemoglobin?
Hemoglobin, a compound present in red blood cells, gives blood its red color. The molecular structure of hemoglobin allows hemoglobin to bind with oxygen (within the red blood cell). Circulation of red...