CHAPTER 18 - HEMATOLOGY

Hemoglobin Determination

A decreased hemoglobin level occurs with anemia (especially iron-deficiency anemia)

Hemoglobin

A major portion of the erythrocyte consists of hemoglobin, a complex compound that transports oxygen and is responsible for the red color of the erythrocyte. The amount of hemoglobin in the blood averages 12 to 16 g/dL for a woman and 14 to 18 g/dL for a man.

Leukocytosis

Is the condition of having an abnormal increase in the number of leukocytes greatest than 11,000 per cubic millimeter), and leukopenia is the condition of having an abnormal decrease in the number of leukocytes (less than 4500 per cubic millimeter)

Trombocytes

Platelets, also known as thrombocytes, are small, clear, and disc shaped.

PT/INR

The PT/INR test is a combination of a PT (prothrombin time) test and a mathematical calculation performed on the PT test to arrive at a standardized value known as an INR (International Normalized Ratio). The PT test result measures how long it takes an individual's blood to form a clot. PT test results are measured in seconds. The reference range for a PT for an adult is 10 to 20 seconds; this means that the blood of a healthy adult should clot within 10 to 20 seconds. The PT/INR result is expressed as a number, and because the value is a ration, the result does not have a unit of measurement attached to it. A healthy individual with a normal clotting ability should have a PT/INR result that falls between 0.8 and 1.2. The higher the number, the longer it takes for the blood to clot. For example, an individual with a PT/INR of 3.0 would have blood that takes longer to clot than an individual with a PT/INR of 1.0. The risk od spontaneous bleeding begins to rise dramatically as the INR reaches a level of 4.0 or higher

Purpose of PT/INR

The PT/INR test is most commonly performed on patients undergoing long term warfarin therapy. The most common conditions for which warfarin is prescribed is prescribed is for thrombophlebitis (also known as deep vein thrombosis, or DVT). The usual desired PT/INR range for a patient on warfarin therapy following a stroke or heart attack, or for a patient with recurring atrial fibrillation, is between 2.0 and 3.0. The PT/INR for a patient with a mechanical valve replacement has a higher range, which falls between 2.5 and 3.5. The goal of warfarin therapy is to increase the clotting time to a level that prevents the formation of blood clots without causing excessive bleeding or bruising. Once the test results become stabilized, a patient on long-term warfarin therapy should have a PT/INR test performed every 2 to 4 weeks.

Hematocrit

The purpose of the hematocrit is to measure the percentage volume of packed red blood cells in whole blood. The hematocrit reference range for a woman is 37% to 47% and the reference range for a man is 40% to 54%.

Hemolysis

Toward the end of this time, it becomes more and more fragile and eventually ruptures and breaks down; this process is known as hemolysis