Polycythaemia-  red cell #Erythrocytosis – in red cell massAbsolute Erythrocytosis- M: Hct >0.60 or >0.52 + RCM >25% of mean- F: Hct >0.56 or >0.48 + RCM >25% of meanApparent Erythrocytosis- Men: Hct >0.52 + normal RCM- Women: Hct >0.48 + normal RCMRelative erythrocytosis-Normal RCM + Reduced plasma volume (pathological dehydration)M>FMedian >60yo2' PRV: treat underlying cause +/- venesection (higher hct threshold)Classification of Absolute:EPO dependent-        Appropriate: High altitude, chronic hypoxia, localised hypoxia, congenital-        Inappropriate: Tumors, EPO doping, Testosterone replacement, diabetic medsEPO independent:-        Acquired: Primary PRV  (low EPO level, feedback)-        Congential Polycythemia= mutations in EPO receptorsInv:- Tumor Hunt- Hx + Exam: ?True vs. Apparent- FBC, U+E, LFTs, Ca2+ - Blood film- Ferritin: low in 1’ PRV- EPO- Imaging- NB:  Normal Hct + High Red Cell # + Low MCV + Low ferritin –> Masked PRV- Molecular Testing:JAK2 (V617F)(96-97%)...SAMURAI JACK=BLOODY)EXXON 12 (3%)Del (13q), Del (20q), Del (1q), Tris. 8/9- *SV thrombus 50% chance MPN- BMBx: Tri-lineage myeloid expansion- Familial screen for congenital(young) Sx of primary PRV:-  Arterial*+ Venous clot (splanchnic*)- Hyperviscosity sx- Splenic sx- GoutIndications for urgent venesection...Hyperviscosity sxBSH diagnostic:JAK2 Pos - Hct M >0.52, F > 0.48. Or RCM >25% above baseline OR Splanchnic vein thrombus - JAK2 positive  JAK2 Neg= A1-4 + either ≥ 1 A or 2 B’sA1: Hct M >0.60, F > 0.56. Or RCM >25% above baselineA2: No JAK2 A3: No 2' cause A4: BMBx posA5: Palpable splenomegalyA5: Acq. genetics in BM cellsB’s: Plt >450, Neut >10 (>12.5 in smokers), Radiological splenomegaly, Low EPO Congenital testing Risk Stratification:- Thrombi.. ECLAP studyHigh Risk:>65 + prev clotsLow Risk: -  Malignant Transformation to MF (5-15% in 10 years), AML (2% at 10 year) markers:Splenomegaly, LDH, HVAF burden >50% at diagnosisManagement:- Lifestyle...CV factors decrease- Aspirin +PPI for all (after confirmed)- decrease CV events 60% (ECLAP) - Venesection first line (?isovolemic)- sx***CYTO-PV trial: Hct aim 400-450ml offWeekly -> 3-4x/year- If previous clots: Lifelong anticoag (w/out aspirin)- NB: if plt>1000 (acq. VWF) bleeding risk, 1st cytoreduceCytoreduction: (once confirmed primary PRV)- High risk- Progressive Hepatosplenomegaly- Plts >1500- WCC >15- Constitutional Sx- Poor tolerance of venesection1st line: (OHC then/or IFN)OHC- Risk:  Macrocytosis, ulcers, SCC, Malignant transformationNB: pregnancyPeg IFN-AYoung + fertileLowers HVAFPROUD PV study (2020)Continuation PV study (2022)SE: flu like sx, AI disease (*thyroid), mood disturbances2nd line Rux: JAK2i (works for EXXON) RESPONSE + RESPONSE 2 trial MAJIC PV studySE: immunosuppression, skin cancer, wean dont stopOlder Busulfan: 1 dose (w monitoring) vs intermittentRisk: leuk transformation, pneumonitis**Pregnancy: inc. DVTOHC not safe (stop 3 months prior)IFN 1stAspirinUterine Doppler from 20wks of gestation?flowLMWH 6 wks postpartum