It is a disease state in which the proportion of blood
volume that is occupied by red blood cells increases.
An increase in the no of red blood cells =absolute
Due to decrease in the volume of plasma =relative
Hematocrit — Polycythemia in the adult patient is
suspected when the HCT is >48 or >52 % in F and M,
(The hematocrit (HCT) is expressed as the percent of a
blood sample occupied by intact RBCs. )
Hemoglobin concentration — when the HGB is >16.5
or >18.5 g/dL in F and M, respectively.
(The hb concentration (HGB) is its content in grams per
100 mL of whole blood. )
SecondaryPrimary Polycythemia overtransfusion
Increase rbc Decrease bld volume
Dec O2, altitude, Ca
It is an apparent rise of the erythrocyte level in the
The underlying cause is reduced blood plasma.
Relative polycythemia is often caused by loss of body
fluids, such as through burns, dehydration and stress.
A specific type of relative polycythemia is Gaisböck
syndrome: mild obesity, diastolic htn, ↓ in plasma vol
with relative ↑ in RBC
Overproduction of RBC may be due to a primary
process in the bone marrow= myeloproliferative
May be a reaction to chronically low oxygen levels.
Polycythemia vera is one of the chronic
myeloproliferative disorders (neoplasms), collectively
characterized by clonal proliferation of myeloid cells.
The most prominent feature of this disease is an
elevated absolute RBC mass because of uncontrolled
red blood cell production.
This is accompanied by ↑ WBC and platelet production
PP: Polycythemia Vera
There is mutation on the Janus kinase-2 gene (JAK2)
JAK2 is directly involved in the intracellular signaling
of progenitor cells in bone marrow.
The peak incidence of PV is age 50-70 years.
Symptoms of PV are often insidious in onset, and they are
often related to blood hyperviscosity.
Symptoms are related to
2. sludging of blood flow
which lead to poor oxygen delivery and symptoms that
include headache, dizziness, vertigo, tinnitus, visual
disturbances, angina pectoris, or intermittent
Bleeding complications (1%) include epistaxis, gum
bleeding, ecchymoses, and gastrointestinal (GI)
Thrombotic complications (1%) include venous
thrombosis or thromboembolism and an ↑prevalence
of stroke and other arterial thromboses.
Abdominal pain due to PUD is present because PV is
associated with ↑ histamine levels and gastric acidity.
Splenomegaly, when present, can cause early satiety
because of gastric filling being impaired by the
enlarged spleen .
Pruritus(40%) results from ↑ histamine levels released
from ↑ basophils and mast cells.
Polymerase chain reaction :JAK2 mutation
Serum Epo assay: are often below the lower limit of
Leukocyte alkaline phosphatase distinguises PV from
Phlebotomy or bloodletting.
(Reduce the hematocrit to the range of <45%.)
Anagrelide is a inhibits megakaryocyte maturation, thereby
decreasing platelet counts.
JAK1/JAK2 inhibitor : ruxolitinib
Hydroxyurea & Interferon alfa
PROGNOSIS — The median survival of untreated symptomatic
patients with PV was initially estimated at 6 to 18 months from the
time of diagnosis, whereas current survival of treated patients is 10
years or more.