Types of Myeloproliferative Disorders on the Physician Assistant Exam
There are different types of myeloproliferative disorders, but for the Physician Assistant Exam (PANCE), focus on polycythemia vera Polycythemia vera is a myeloproliferative disorder (MPD). Myeloproliferative disorders are diseases of the bone marrow that involve increased cell turnover..
Polycythemia is the exact opposite of anemia — too many red blood cells are being produced. You commonly see polycythemia in both men and women over the age of 60. Here are some key points concerning polycythemia vera (PV):
Clinical presentation includes vision problems and headaches. After a hot shower, a person with polycythemia may feel intense itching (yet another reason to take a cold shower!).
Physical examination can show high blood pressure and splenomegaly.
The CBC clues you in to a possible diagnosis with an elevated hemoglobin and hematocrit. You make the diagnosis by determining red cell mass. Some patients can also have a high platelet count (thrombocytosis) as well.
The treatments include phlebotomy to keep the hematocrit lower, as well as hydroxyurea or anagrelide as needed. It’s also recommended that the patient take an antiplatelet agent such as aspirin to minimize the risk of stroke, coronary events, and other clotting events.
The second type of polycythemia is called secondary polycythemia, meaning that something in the body, usually lack of oxygen, or hypoxemia, is driving erythropoietin production. Examples of this include COPD and cyanotic heart disease. Remember that renal cell carcinoma and polycystic kidney disease can have a secondary polycythemia as well through increased production of erythropoietin.
The third type of polycythemia is called relative polycythemia. It refers to a state when the hemoglobin and hematocrit levels are elevated because of extreme volume depletion and/or dehydration. The hemoglobin and hematocrit levels normalize with IV hydration.