blood lab manual

Blood is a type of connective tissue composed of formed elements and a liquid matrix called plasma. This liquid tissue circulates throughout the body in a closed circuit of vessels, delivering nutrients and molecules such as hormones and drugs, while also removing waste products from body tissues.

Leukocytes (a type of formed element) and various molecules circulate in the blood to protect against potentially harmful substances, while platelets (thrombocytes) function to protect against blood loss. A person’s overall health can be assessed through the use of blood diagnostic tests.

The following are examples of diagnostic tests performed:

• White Blood Cell Differential — measures the amount of each type of leukocyte circulating in the blood and is useful in diagnosing specific diseases and/or infections.

• Hematocrit — measures the proportion of circulating erythrocytes, which are responsible for transporting respiratory gases (O₂ and CO₂). An abnormally low hematocrit may indicate anemia.

• Coagulation Time — determines the amount of time required for a blood clot to form. The risk for bleeding increases as coagulation time increases.

• Blood Type — is genetically determined by the presence or absence of surface antigens on red blood cells and circulating antibodies. Determining blood type is essential prior to blood transfusions to ensure compatibility.

• Blood Glucose — measures the concentration of glucose in the blood and is commonly used to assess metabolic function.