New diagnostic criteria -PV

Subject: PV criteria

Helen and all,

I hope I wasn't too confusing - anyway I thought perhaps some

clarification might help (for example, Helen, in the 3 PVSG criteria it

would be high hematocrit due to increased RCM). So please find below some

new criteria for diagnosing polcythemia vera taken from LEUKEMIA AND

LYMPHOMA, 1996 by Pearson and Messinezy. They mention that the original

PVSG criteria is 20 years old and needs to be updated (which they then do).

I have included the old PVSG criteria in parentheses as applicable and

added some notes at the bottom.

Major criteria:

1. Increased red cell mass greater than 25% above the patient's mean

normal predicted value based on surface area. (The old PVSG used an older

method of detecting RCM and said equal or above 36 mL/kg for males; 32

ml/kg for females.)

2. Absence of a cause of secondary polycythemia (The old PVSG used

arterial oxygen saturation of above 92% here.)

The above two criteria are considered essential - in addition, a third

major criteria being;

3. Palpable splenomegaly OR a marker of clonal hematopoiesis (chromosome

abnormality). (The old PVSG just used splenomegaly here.)

The diagnosis of PV is considered supported with all of the above three

criteria (the first two, and one of the third). HOWEVER, if only the first

2 major criteria exist, then two minor criteria (below) should be present

to secure diagnosis.

Minor criteria:

1. Platelet count above 400,000

2. Neutrophil count above 10 (The PVSG had leukocytosis above 12 with no

fever or infection.)

3. Splenomegaly confirmed by a scanning technique

4. BFU-E growth (BFU-E is burst-forming unit- erythroid; this goes along

the line of the endogenous erythroid colony (EEC) test.)

5. Reduced serum erythropoietin level

The old PVSG minor criteria were the first two as noted above and then

dealt with elevated LAP or vitamin B12 levels for the other minor criteria.

So, to repeat, Pearson & Messinezy are suggesting that either all of the

three major criteria should be present OR the first two major criteria with

two minor criteria for a diagnosis of polycythemia vera.

NOTES: None of the criteria listed require a biopsy. However, if red cell

mass is not performed before phlebotomy, then it is not valid. (According

to sources - biopsy IS valuable, if necessary, to determine P.vera

diagnosis as opposed to other types of polycythemia. However, it may not be

that valuable in determining between P. vera and essential thrombocythemia.

References available.)

The newer red cell mass/plasma volume tests (preferred by

Pearson/Messinezy & also mentioned in other articles) take into account

body height & obesity (I don't understand it all); it is also mentioned in

articles that seasonal variations, exercise, time of day, obesity, smoking,

etc., can affect these measurements.

Also note that where the older PVSG major criteria number two was just to

confirm the oxygen level - the new criteria listed by P & M says that

secondary causes should be ruled out (an oxygen saturation test does not by

itself rule out all known causes of secondary polycythemia).

And, under the new minor criteria # 4, though the BFU-E (or EEC) listed

would fit in as being tested from the peripheral blood (just from blood

drawn); if used from marrow blood (collected from aspiration - as with a

biopsy) - some sources have said it would then be a positive indicator of

polycythemia vera (references available).

A normal or elevated erythropoietin level would be more indicative of a

secondary polycythemia (with a reduced level indicating P. Vera). It's

just a minor criteria, though, since overlap can occur.