Polycythemia Report

8/9/2019 Polycythemia Report

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Polycythemia


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IntroductionPolycythemia- is an increase number of red blood

cells in the blood. In polycythemia the levels ofhemoglobin (Hb), Hematocrit (Hct)-is the ratio of thevolume of red cells to the volume of whole blood orthe red blood cell (R!) count maybe elevated whenmeasured in the complete blood count (!!) ascompared to normal. Hemoglobin levels " #$.% g&d'in women and "#.% g&d' in men suggestpolycythemia. In terms of hematocrit, a value " inwomen and %* in men is indicative of polycythemia.

+eaning Polycythemia is characteried by anincrease in absolute /uantity of red cells or total R!volume. In contrast, relative polycythemia(pseudoerythrocytosis) is secondary to 0uid loss ordecreased 0uid inta1e resulting in

hemoconcentration.


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2ormal HematopoiesisProduction of red blood cells (erythropoiesis)

occurs in the bone marrow. +yeloid stem cellsgive rise to erythrocytes, platelets,granulocytes, eosinophils,basophils, andmonocytes. 3he production of each lineage is afunction of cell proliferation, di4erentiation andapoptosis.3hese various stages of di4erentiation rely onmultiple interrelated processesProtein growth factors, 1nown as cyto1ines,

stimulate proliferation of the multilineage cells.5ne of the important enymes regulating thisprocess is called erythropoietin (6po). 3hema7ority of 6po is produced and released by the1idneys, and a smaller portionis released by the

liver.


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3ypes

Primary polycythemias

- Polyvythemia can result from internalproblems with the production of R!.

- It is due to factors intrinsic to red cell

precursors , including primary familialand congenital polycythemia (P8!P),idiopathic erythrocytosis andpolycythemia vera(P9).

:econdary polycythemia - If polycythemia is caused due to

another underlying medical problem, it is

referred to as secondary polycythemia.


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- 3hese are caused by factors e;trinsicto red cell precursors and include a

physiologic appropriate erythropoietin(epo) production in response to tissuehypo;ia.

+ost cases of polycythemia are secondaryand are caused by another medicalcondition. Primary polycythemias arerelatively rare< for e;ample, polycythemia

vera occurs in appro;imately # to * adultsper #==,=== in the >:. #? to %? ofnewborns can have polycythemia(neonatal polycythemia).


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Relative Polycythemia

- relative polycythemia describes

conditions in which red cell volume ishigh due to increased bloodconcentration of red cells as a result ofdehydration.

:tress Polycythemia


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6tiologyPolycythemia Primary !auses

- Inherent or ac/uired problems with redblood cell production lead to polycythemia.

- 3wo main conditions that belong to thiscategory are polycythemia vera (P9 or

polycythemia rubra vera@PR9A) and primaryfamilial and congenital polycythemia (P8!P).

- Polycythemia vera is related to a geneticmutation in the BCD* gene, which is thought to

increase the sensitivity of bone marrow cellsto 6po, resulting in increased red bloodcellproduction. 'evels of other types of bloodcells(wbc and platelets) and also often

increased in this condition.


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- Primary familial and congenital polycythemia (P8!P) isa condition related to a mutation in the 6P5R gene andcauses increased production of R! in response to 6po.

Polycythemia :econdary !ause

- over production of R! results from increasedsensitivity or responsiveness to 6po( often with lowerthan normal levels of 6po), in secondary polycythemia ,more red cells are produced because of high levels of

circulating 6po.

- the main reasons for higher than normal 6po arechronic hypo;ia (poor blood o;ygen levels over the longterm), poor o;ygen delivery due to abnormal R!

structure, and tumors releasing inappropriately highamounts of 6po.

- :ome common conditions that can result in elevatederythropoietin due to chronic hypo;ia or poor o;ygen

supply includes !5PE, emphysema, chronic bronchitis.


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> pulmonary hypertension> congestive heart failure> obstructive sleep apnea> 1idney cancer (renal cell carcinoma)> uterine cancer> chronic carbon mono;ide e;posure can also

lead to polycythemia.Hemoglobin naturallyhas a higher aFnity for carbon mono;idethan for o;ygen. 3herefore, when carbonmono;ide molecules attach to hemoglobin,polycythemia (increased red cell andhemoglobin production)may occcur in orderto compensate for the poor o;ygen deliveryby the e;isting hemoglobin molecules. Csimilar scenario can also occur with !5* in

long term cigarette.


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2eonatal polycythemia is often caused by transfer ofmaternal blood from the placenta or bloodtransfusions. Prolonged poor o;ygendelivery to thefetus (intrauterine hypo;ia) due to insuFciency of

the placenta can also lead neonatal polycythemia.Relative Polycythemia

- in theses situations(vomiting, diarrhea,e;cessivesweating) the number of R! is normal,but because

of the 0uid loss a4ecting the blood(plasma), redblood cell counts may seem elevated.

:tress Polycythemia

- this is a condition that may be seen in

hardwor1ing, an;ious, middle-aged men due to lowplasma volume, although the R! volume may benormal.

- other names for this condition are

pseudopolycythemia, stress erythrocytosis, orGaisboc1s disease.


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Polycythemia Ris1 8actors chronic hypo;ia

long term cigarette smo1ing familial and predisposition< living in high altitudes< long term e;posure to carbon mono;ide

(tunnel wor1ers, car garage attendants,residents of highly polluted cities)and

ash1enai 7ewish ancestry(may haveincreased fre/uency of polycythemia veradue to genetic susceptibility).


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:igns :ymptomseasy bruising

easy bleedingblood clot formation(potentially leading to@pulmonary embolismA)

Documents

Polycythemia Report