Clinical Hematology Polycythemia

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Polycythemia:
Increase in the concentration of RBCs in the blood above normal levels for both age and sex, usually, but not always the Hb and Hct are increased.
3 Major Classes of Polycythemia:
Relative erythrocytosis
Absolute
Secondary erythrocytosis
Relative Erythrocytosis:
Increase in RBC due to decreased plasma volume. Total RBC mass is normal.
Relative Erythrocytosis due to dehydration caused by:
Severe diarrhea, vomiting, shock, hypertension, severe burns, acute hemorrhage and shock,
Relative Erythrocytosis due to stress polycythemia:
Also called spurious or Gaisbock's Syndrome. Usually seen in men who are smokers, obese, and have hypertension.
Polycythemia Vera:
Primary polycythemia or absolute polycythemia, also known as Osler's Disease. One of the myeloproliferative syndromes, disorders arising at the stem cell. Characterized by uncontrolled growth and proliferation of predominantly erythroid precursors. Cause is unknown. Disease of middle-aged and elderly persons, mostly men. Uncommon in blacks, common in Ashkenazy Jews. Urinary erythropoietin levels are low, hormone secretion is suppressed.
Polycythemia Vera clinical features:
Face appears suffused with blood, retinal veins are engorged, frequent headaches, dizziness, blurred vision and tinnitus. Sluggish blood- peripheral cyanosis, thromboembolic complications common, splenomegaly in 75%, increased peptic ulcers, pruitis after a hot shower.
Polycythemia Vera Lab findings:
RBC, Hb, Hct increased. Indices normal with variable poik and aniso, increased WBC may be seen with mature myeloid cells and increased basophils, thrombocytosis, LAP score is increased (70%), bone marrow shows hyperplasia of all cell lines with no stable storage iron.
Polycythemia Vera treatment:
Phlebotomies, cytotoxic therapy if platelets present problems.
Polycythemia Vera prognosis:
Chronic disease- patient lives 10-20 years with therapy. In 15-20% of patients, after about 10 years the disease gives rise to a "spent" stage. Life expectancy is then about 3 years. Bone marrow becomes fibrotic. Enlarged spleen. Blood picture similar to MMM (teardrops and NRBCs), May transform to acute basophilic leukemia's (15%).
Polycythemia Vera Diagnosis:
To establish a diagnosis of polycythemia Vera either all 3 diagnostic criteria from category A or an elevated red cell mass and normal arterial oxygen saturation in addition to two criteria from category B.
Category A:
Elevated Red cell mass, Normal arterial oxygen saturation, splenomegaly
Category B:
Leukocytosis, thrombocytosis, elevated LAP score, increased serum vitamin B-12 binding proteins.
Secondary Polycythemia:
Increased erythropoietin due to decrease in oxygen received by the tissues. Arterial oxygen unsaturation- lack of oxygen reaching the blood results in arterial unsaturation and impaired oxygen delivered to tissues and increased production of erythropoietin. Causes the bone marrow to have hyperplasia of RBCs only.
Secondary Polycythemia caused by:
High altitude, chronic pulmonary disease, cyanotic heart disease, cigarette smokers, increased Methemoglobin, myocardial infarction, carboxyhemoglobin, malignancies.
Recessive Familial Polycythemia:
Hereditary. Increased production due to a defect in the regulation of the production of erythropoietin.
Benign Familial Polycythemia:
Rare disorder, increased erythropoietin but the bone marrow is not hyperplastic.