Polycythemia Flashcards Preview

SADL Haematology > Polycythemia > Flashcards

Flashcards in Polycythemia Deck (15):

Causes of neonatal polycythemia

1. Intrauterine hypoxia - SGA, previa, maternal HTN, smoking, maternal heart disease

2. Hypertransfusion - TTTS, materno-fetal, delayed cord clamping

3. Endocrinopathy

4. Chromosomal - T13, 18, 21. BWS

5. Altitude

6. High-affinity Hb


Neonatal polycythemia - when to treat?

HCT 65% with symptoms
70% when asymptomatic

Exchange transfusion to target HCT 50-55%
Ex vol (ml)=((observed HCT-desiredHCT)x bloodvolume) /observed HCT


Childhood polycythemia Classification/Differential

1. Relative Polycythemia (hemoconcentration, dehydration)

2. Primary Polycythemia: Congenital-Primary Familial Congenital Polycythemia (PFCP) (EPOR mutation d/t germline mutation), Acquired-polycythemia vera (due to somatic mutation)

3. Secondary Polycythemia :
(A) Insufficiency oxygen delivery
Physiologic: Fetal life, low environmental oxygen
Resp or Cardiac disease, AV shunts
Abnormal Hb: methemoglobinemia, carboxyhemoglobinemia, 2,3-BPG deficiency
(B) Increase in EPO (inappropriate polycythemia)
i. Endogenous: Renal, Endocrine,Liver, cerebellum, uterus, ovaries
Ii. Exogenous: testosterone and growth hormone
(C)Polycythemia with characteristics of both primary and secondary polycythemias
Chuvash, other VHL mutations, HIF2alpha gene and PHD2 gene mutations


Treatment of PV

Phlebotomy to keep HCT<45%
Low-dose ASA
Cytoreductive chemotherapy
- HU 20-30mg/kg
- INFalpha
- Anagrelide


High-affinity hemoglobins
- inheritance
- testing

- Auto dominant
- typically B globin defects
- P50 (partial pressure at which 50% of hemoglobin carries oxygen). Should be decreased (also for 2,3BPG deficiency). Beta globin sequencing is gold standard.


What should all polycythemic neonates be monitored for?



what complications can occur as a result of neonatal polycythemia?

tachypnea and resp distress-TTN


what is the cause of primary polycythemia

results from somatic or germline mutations of erythroid progenitor cells that make them very sensitive to EPO or other cytokines


What is the definition of childhood polycythemia?

Hb >170 or hematocrit >50%
(or Hb >99%ile for age)


what is the most common mutation leading to PV?

JAK2 V617F
(a gain of function kinase at codon 617)

Other type of mutation is JAK2 exon 12 mutation


For the treatment of PV when should cytoreductive therapy be used?

prior hx of thrombosis or TIA OR
platelet count >1.5million


What is Chuvash polycythemia?

AR disorder, caused by loss of function mutation in VHL gene
Can be grouped as a primary polycythemia because erythroid progenitors are sensitive to EPO
Can also be called a secondary polycythemia because EPO itself can be upregulated
Clinical symptoms are varicose veins, vascular anomalies, plethora, symptoms of polycythemia


what is 2,3-DPG?

promotes hemoglobin transition from high oxygen affinity state to a low oxygen affinity state. It binds to the central portion of the hemoglobin tetramer, changing its conformation and shifting the 02 dissociation curve to the right


What initial testing should be done in a patient with polycythemia

family hx!
EPO level
measure 02 saturation (arterial)
imaging-renal, look for masses


what is methemoglobin

generated when oxygen carrying ferrous iron (Fe2+) has been oxidized to ferric iron (Fe3+) which can't bind O2
the acquired form happens due to oxidizing substances like nitrates and sulf containing antibiotics
Patient presents with cyanosis and low oxygen saturation by pulse oximetry but has normal PaO2 level