Download Polycythemia Rubra Vera

Polycythemia (Erythrocytosis)
Primary Polycythemia (Polycythemia Rubra Vera)
Polycythemia exists when the red blood cell (RBC) count, hemoglobin level, and total RBC
volume all exceed the upper limits of normal.
In postpubertal individuals, an RBC mass >25% above the mean normal value (based on body
surface area), or hematocrit >60 (in males) or >56 (in females) indicates absolute erythrocytosis.
A decrease in plasma volume, such as occurs in acute dehydration and burns, may result in a
high hemoglobin value. These situations are more accurately designated as hemoconcentration
because the RBC mass is not increased and normalization of the plasma volume restores
hemoglobin to normal levels.
1.
Diagnosis of Polycythemia Vera
MAJOR CRITERIA
4. Increased vitamin B12 (>900
pg/mL) or unbound B12 binding
Increased red cell mass
capacity (>2,200 pg/mL)
Arterial O2 saturation of ≥92%[*]
DIAGNOSIS
Palpable splenomegaly
All 3 major criteria
MINOR CRITERIA
1, 2, and 2 minor criteria
9
Platelet count of >400 × 10 /L
2.
Leukocytosis of >12 × 109/L
3.
Increased
leukocyte
phosphatase
1.
2.
3.
*
alkaline
Absent causes of secondary polycythemia
CLINICAL MANIFESTATIONS.
Patients with polycythemia vera usually have hepatosplenomegaly.
Erythrocytosis may cause hypertension, headache, shortness of breath, or neurologic symptoms.
Granulocytosis may cause diarrhea or pruritus from histamine release.
Thrombocytosis (with or without platelet dysfunction) may cause thrombosis or hemorrhage.
TREATMENT.
Phlebotomy is the initial treatment of choice.
Iron supplementation should be given to prevent viscosity problems from microcytosis.
Antiplatelet agents (aspirin) may reduce the risks of thrombosis and abnormal bleeding in
patients with marked thrombocytosis.
If this is unsuccessful, antiproliferative treatments (hydroxyurea, anagrelide, interferon-α) may
be helpful.
The risk of transformation of the disease into myelofibrosis or acute leukemia has diminished
with discontinuation of the use of alkylating agents and radioactive phosphorus.
Prolonged survival is not unusual.
Secondary Polycythemia
Polycythemia may be present in any clinical situation associated with chronic arterial oxygen
desaturation.
Cardiovascular defects involving right-to-left shunts and pulmonary diseases interfering
with proper oxygenation are the most common causes of hypoxic polycythemia.
Clinical findings usually include cyanosis, hyperemia of the sclerae and mucous membranes, and
clubbing of the fingers.
As the hematocrit rises to >65%, clinical manifestations of hyperviscosity, such as headache and
hypertension, may require phlebotomy .
Living at high altitudes also causes hypoxic polycythemia; the hemoglobin level increases
approximately 4% for each rise of 1,000 M in altitude.
Partial obstruction of a renal artery rarely results in polycythemia.
Differential Diagnosis of Polycythemia
Altitude
POLYCYTHEMIA VERA
Cardiac disease
SECONDARY
Familial
Lung disease
Hemoglobinopathy
Central hypoventilation
High–oxygen affinity variants
Metabolic
Methemoglobin reductase deficiency
2, 3-diphosphoglycerate deficiency
Chronic carbon monoxide exposure
Neonatal
Hormonal
Normal intrauterine environment
o Adrenal disease
o Virilizing
syndrome
hyperplasia,
Twin-twin or maternal-fetal hemorrhage
Cushing
o Anabolic steroid therapy
Malignant tumors
Adrenal, cerebellar, hepatic, other
Renal disease
Cysts, hydronephrosis
Infants of diabetic mothers
Intrauterine growth retardation
Trisomy 13, 18, or 21
Adrenal hyperplasia
Thyrotoxicosis
SPURIOUS (PLASMA VOLUME
DECREASE)
Hypoxia
More subtle forms of hypoxia may also cause polycythemia.
Congenital methemoglobinemia resulting from a deficiency of cytochrome b5 reductase may
cause cyanosis and polycythemia . This condition is transmitted as an autosomal recessive trait.
Most affected individuals are asymptomatic. Neurologic abnormalities may be present in patients
whose enzyme deficit is not limited to hematopoietic cells. Dominantly transmitted polycythemia
is caused by hemoglobins that have increased oxygen affinity. Cyanosis may occur in the
presence of as little as 1.5 g/dL of methemoglobin, but is uncommon in other hemoglobin
variants unless hyperviscosity results in localized hypoxemia .
Polycythemia has also been associated with benign and malignant tumors that secrete
erythropoietin.
Exogenous or endogenous excess of anabolic steroids also may cause polycythemia.
Polycythemias have been transmitted as dominant or recessive conditions.
In some families, there is an abnormality of the erythropoietin receptor or the von-Hippel Lindau
gene.
TREATMENT.
For mild disease, observation is sufficient.
When hematocrit is >65–70% (hemoglobin >23 g/dL), blood viscosity markedly increases.
Periodic phlebotomy may prevent or decrease symptoms.
Apheresed blood should be replaced with plasma or saline to prevent hypovolemia in patients
accustomed to a chronically elevated total blood volume.
Increased demand for red blood cell production may cause iron deficiency.
Iron-deficient microcytic red cells are more rigid, further increasing the risk of intracranial and
other thromboses in patients with polycythemia.
Periodic assessment of iron status, with treatment of iron deficiency, should be performed.
Dr.Hayder al-Musawi