Diagnosis guide for clinicians

Polycythemia vera: when to suspect it and what to test

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Polycythemia vera (PV) is a JAK2-mutated myeloproliferative neoplasm marked by clonal erythrocytosis, with a raised risk of thrombosis and of progression to myelofibrosis or acute myeloid leukemia.Source Tefferi and Barbui 2023

In an international study of 1545 patients, palpable splenomegaly, pruritus and vasomotor symptoms were each present in about a third at diagnosis, and 16% had an arterial thrombosis before or at diagnosis.

Source International PV study (Tefferi 2013)

In a 4-center study of 612 patients with myeloproliferative neoplasms, 44% had blood counts that met diagnostic criteria at least 3 months before diagnosis, and 25% had a vascular complication before diagnosis.

Source Enblom 2015

16.5 and 16.0g/dLHemoglobin thresholds for men and women in the WHO and ICC criteria; the hematocrit thresholds are 49% and 48%ICC 2022 criteria (Gianelli 2023)

98%Share of screened patients with a JAK2 mutation in a 1545-patient international study: V617F in 95% and other JAK2 mutations in 3%International PV study (Tefferi 2013)

2.9 yearsAverage time aquagenic itching preceded diagnosis in a 441-patient German survey, among the 64.8% in whom it came firstSiegel 2013

D45ICD-10-CM code, Polycythemia veraNLM ICD-10-CM lookup

Orphanet recordORPHA:729 ↗

Inheritance

Not applicable

Age of onset

All ages

Prevalence

1 to 9 per 100,000 annual incidence, Europe
1 to 5 per 10,000 point prevalence, Europe

Also called

Acquired primary erythrocytosis, Osler-Vaquez disease, PV, Polycythemia rubra vera, Vaquez disease

Live from Orphanet (INSERM) via Orphadata, licensed CC BY 4.0, data version 2026-06-23.

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Patterns to test Red flags Often mistaken for What to test Family screening ICD-10 codes Once confirmed For the patient

Patterns that should prompt a test for Polycythemia vera

Each sign below is common on its own, which is why Polycythemia vera is missed. Published studies describe these combinations as the picture to act on. Rows are ordered from the highest published figure to the lowest, within each kind of measure.

Where testing finds it

Share of each screened or biopsied group found to have Polycythemia vera, from the cited studies. A bar spans the lowest to the highest published figure.

1
Erythrocytosis+Serum erythropoietin below the normal range
186 patients with absolute erythrocytosis who had erythropoietin measured in 8 French hospital centers, 116 of them with polycythemia vera
A level below the normal range had a 97.8% positive predictive value and 97% specificity for polycythemia vera, and was found in 87% of those with it (Mossuz 2004).Mossuz 2004
97.8%
2
Budd-Chiari syndrome+JAK2 V617F testing
1062 patients with Budd-Chiari syndrome pooled in a meta-analysis
JAK2 V617F was found in 41.1% and a myeloproliferative neoplasm in 40.9%; polycythemia vera was more prevalent here than in portal vein thrombosis (Smalberg 2012).Smalberg 2012 meta-analysis
41.1%
3
Portal vein thrombosis without cirrhosis or malignancy+JAK2 V617F testing
855 patients with nonmalignant, noncirrhotic portal vein thrombosis pooled in the same meta-analysis
JAK2 V617F was found in 27.7% and a myeloproliferative neoplasm in 31.5% (Smalberg 2012).Smalberg 2012 meta-analysis
27.7%
4
Erythrocytosis referred for work-up+JAK2 and erythropoietin testing
213 patients investigated for erythrocytosis with JAK2 and erythropoietin testing at a tertiary center in Hamilton, Canada, 2017 to 2022
JAK2 mutations were found in 40 of 213 (19%); the authors expect the share in primary care to be likely under 1% (Senecal 2025).Senecal 2025
19%
5
Splanchnic vein thrombosis+Blood counts without typical features of a myeloproliferative neoplasm+JAK2 V617F testing
Patients with Budd-Chiari syndrome or portal vein thrombosis screened for JAK2 V617F despite lacking typical hematologic features, in the same meta-analysis
Screening identified a myeloproliferative neoplasm in 17.1% of screened Budd-Chiari patients and 15.4% of portal vein thrombosis patients (Smalberg 2012).Smalberg 2012 meta-analysis
15.4% to 17.1%
6
Hemoglobin above 18.5g/dL in men or 16.5g/dL in women+Leukocytosis or thrombocytosis
133 evaluable people with erythrocytosis in the Dutch Lifelines population cohort of 147,167 adults
JAK2 V617F was found in 7 of 133 (5.3%), all 7 with a second raised cell line; the JAMA review gives this as 7 of 45 (15.6%) against 0 of 88 with isolated erythrocytosis (Wouters 2020).Lifelines cohort (Wouters 2020)
15.6%
7
Ischemic stroke+JAK2 V617F testing
10,428 patients in the Chinese CNSR-III ischemic stroke cohort with targeted sequencing data
JAK2 V617F was found in 46 of 10,428 (0.4%); higher platelet count and hemoglobin and fewer traditional stroke risk factors predicted it (Zhao 2026).Zhao 2026
0.4%

How often diagnosed patients show it

Share of patients already diagnosed who had the finding, in the group named on each row. Groups differ by age and type, so read each row with its group.

1
Erythrocytosis+JAK2 V617F or another JAK2 mutation
1268 patients screened for JAK2 mutations among 1545 with polycythemia vera in a 7-center international study
A JAK2 mutation was found in 1239 of 1268 (98%): V617F in 95% and other JAK2 mutations in 3% (Tefferi 2013).International PV study (Tefferi 2013)
98%
2
Erythrocytosis+Subnormal serum erythropoietin
1058 patients with polycythemia vera tested for erythropoietin in the international study, and 116 in a French study
Erythropoietin was subnormal in 81%, normal in 17% and raised in 2% (Tefferi 2013), and below the normal range in 87% (Mossuz 2004).International PV study (Tefferi 2013)
81% to 87%
3
Hematocrit above 52% in men or 48% in women+JAK2 V617F
287 patients studied by a Barcelona group: 99 with polycythemia vera, 137 with essential thrombocythemia and 51 with non-clonal erythrocytosis
This pair had 79% sensitivity and 97% specificity for polycythemia vera; adding low erythropoietin and allele burden together raised sensitivity to 83% (Ancochea 2014).Ancochea 2014
79%
4
Fatigue or headaches for a year or more+Raised hemoglobin or hematocrit
380 US respondents with polycythemia vera in the Incyte-funded MPN Landmark patient survey
At least one related symptom a year or more before diagnosis was reported by 61%, most often fatigue (26%) and headaches (16%) (Mesa 2016).MPN Landmark survey (Incyte-funded)
61%
5
Itch after contact with water+Raised hemoglobin or hematocrit
1349 evaluable patients in the international study, and 441 German patients with polycythemia vera surveyed by questionnaire
Pruritus was recorded at diagnosis in 36% (Tefferi 2013); aquagenic pruritus was reported by 301 of 441 (68%, our division of the reported counts), and in 64.8% it came on average 2.9 years before diagnosis (Siegel 2013).Siegel 2013
36% to 68%
6
Erythrocytosis+Thrombocytosis or leukocytosis
1545 patients with polycythemia vera in the international study
Thrombocytosis was present at diagnosis in 53% and leukocytosis in 49% (Tefferi 2013).International PV study (Tefferi 2013)
49% to 53%
7
Palpable spleen+Raised hemoglobin or hematocrit
1477 evaluable patients with polycythemia vera in the international study
A palpable spleen was found in 534 of 1477 (36%): 40.3% of men and 32% of women (Tefferi 2013).International PV study (Tefferi 2013)
36%
8
Heart attack, stroke or venous clot+Abnormal blood counts in the months before
612 patients with myeloproliferative neoplasms from 4 centers in Sweden, Denmark and France, and 1545 patients with polycythemia vera in the international study
A vascular complication preceded diagnosis in 25% (Enblom 2015); arterial thrombosis before or at diagnosis was recorded in 16% and venous thrombosis in 7.4% (Tefferi 2013).Enblom 2015
7.4% to 25%
9
Microcytosis or iron deficiency+Hemoglobin and hematocrit not raised+JAK2 V617F
208 patients with classical myeloproliferative disease other than chronic myeloid leukemia at a Turkish center
This picture was found in 23 of 208 (11%); the red cell count was raised in 17 of 23, and the authors judged most to be polycythemia vera masked by iron deficiency (Aladağ 2019).Aladağ 2019
11%
10
Burning red hands or feet (erythromelalgia)+Raised hemoglobin, hematocrit or platelets
Patients with polycythemia vera in the studies cited by a 2025 JAMA review
Erythromelalgia is reported in 5.3% of patients, and transient visual changes in 14% (JAMA review 2025).JAMA review 2025
5.3%

Also described, without a comparable figure

Hemoglobin or hematocrit rising from the patient's own baseline + JAK2 mutation + Values still below the WHO thresholds: No frequency for this combination was found; the authors write that it should be approached as polycythemia vera even below the thresholds (Tefferi 2021).Tefferi, Vannucchi and Barbui 2021
Itch after water contact on normal-looking skin + Blood counts not yet abnormal: No frequency for this combination was found; the authors note the itch can appear years before detectable blood count changes (Witte 2025).Witte 2025
Stroke with an evident cause such as atherosclerosis + Raised hemoglobin or platelet count: No screening yield was found for this combination; another stroke mechanism was present in 51% of the 35, and all had hemoglobin or platelet abnormalities (Ong 2016).Ong 2016

These figures describe published study groups. They are not the chance that any one patient has Polycythemia vera, and bars whose ranges overlap are not in a settled order.

Red flags for Polycythemia vera

What the cited sources describe, grouped by life stage and organ. Each line links to its source.

Blood count

The ICC criteria set the thresholds at hemoglobin above 16.5g/dL in men and 16.0g/dL in women, or hematocrit above 49% in men and 48% in women.ICC 2022 criteria (Gianelli 2023)
Median hemoglobin at diagnosis was 18.4g/dL and median hematocrit 55% in the 1545-patient international study.International PV study (Tefferi 2013)
Thrombocytosis was present in 53% and leukocytosis in 49% of those patients at diagnosis.International PV study (Tefferi 2013)
A JAMA review states that spurious and secondary erythrocytosis are not associated with pruritus, leukocytosis or thrombocytosis.JAMA review 2025
In the Dutch Lifelines population cohort, JAK2 V617F was found in 7 of 133 evaluable people with erythrocytosis, and all 7 also had leukocytosis or thrombocytosis.Lifelines cohort (Wouters 2020)
Mayo Clinic and Italian authors write that a documented rise in hemoglobin or hematocrit from a person's own baseline, with a JAK2 mutation, should be approached as PV even below the thresholds.Tefferi, Vannucchi and Barbui 2021
The authors of the 612-patient study conclude that a myeloproliferative neoplasm should always be suspected and ruled out in unexplained elevated hematocrit, leukocyte or platelet counts.Enblom 2015

Itch, hands, feet and vision

The JAMA review describes aquagenic pruritus as intense itching or a prickling sensation in response to water of any temperature, present in about one-third of patients at diagnosis.JAMA review 2025
Pruritus was recorded at diagnosis in 485 of 1349 evaluable patients (36%) in the international study.International PV study (Tefferi 2013)
In a German questionnaire study, 301 of 441 patients with PV reported aquagenic pruritus, mostly on the trunk and the proximal parts of the limbs.Siegel 2013
Most of those patients described itching (71.8%) and the rest tickling, stinging or burning, and 14.6% called it unbearable.Siegel 2013
The British Society for Haematology (BSH) puts pruritus in up to 85% of patients, and notes it can predate the diagnosis and be set off by water or temperature change.BSH 2019 guideline, specific situations
A German multicenter dermatology and hematology group defines aquagenic pruritus as itch after water contact on skin with no visible lesions, sometimes years before detectable blood count changes.Witte 2025
Erythromelalgia is reported in 5.3% and transient visual changes in 14% of patients, according to the JAMA review.JAMA review 2025
Vasomotor symptoms were recorded in 403 of 1412 evaluable patients (28.5%) at diagnosis.International PV study (Tefferi 2013)

Spleen and general symptoms

A palpable spleen was found in 534 of 1477 evaluable patients (36%), more often in men (40.3%) than in women (32%).International PV study (Tefferi 2013)
Splenomegaly can cause abdominal discomfort, the JAMA review notes.JAMA review 2025
A 2026 Mayo Clinic Proceedings review lists pruritus, headache, dizziness and fatigue as symptoms.Mayo Clinic Proceedings 2026
In the Incyte-funded MPN Landmark survey, 61% of 380 respondents with PV reported at least one related symptom a year or more before diagnosis, most often fatigue (26%) and headaches (16%).MPN Landmark survey (Incyte-funded)

Stroke, heart attack and other clots

Arterial thrombosis before or at diagnosis was recorded in 246 of 1545 patients (16%) and venous thrombosis in 114 (7.4%).International PV study (Tefferi 2013)
Venous thrombosis was more frequent in women (9.3% against 5.4%) and arterial thrombosis in men (18% against 14%).International PV study (Tefferi 2013)
The JAMA review breaks these down as acute coronary syndrome in 8.3%, cerebrovascular events in 7.7%, deep vein thrombosis in 4.2% and pulmonary embolism in 2.0%.JAMA review 2025
Thrombosis is the first clinical manifestation in about 20% of cases, according to a 2023 paper by ICC authors.ICC 2022 criteria (Gianelli 2023)
Of 151 vascular complications before diagnosis in the 612-patient study, 66% fell in the 2 years before diagnosis, led by myocardial infarction (46) and ischemic stroke (43).Enblom 2015
At one German university hospital, 17 of 3318 patients with ischemic cerebrovascular events had a related myeloproliferative neoplasm, and the event was its first manifestation in 58%.Stefanou 2019
Recurrent cerebrovascular events before the neoplasm was diagnosed were noted in 29% of those 17 patients.Stefanou 2019
In a French registry of 763 patients, a stroke revealed the neoplasm in 35, of whom 12 had PV; all 35 had hemoglobin or platelet count abnormalities.Ong 2016

Budd-Chiari syndrome and portal vein thrombosis

A meta-analysis of 1062 patients with Budd-Chiari syndrome and 855 with portal vein thrombosis found a myeloproliferative neoplasm in 40.9% and 31.5%.Smalberg 2012 meta-analysis
JAK2 V617F was present in 41.1% of the Budd-Chiari patients and 27.7% of the portal vein thrombosis patients, and PV was more prevalent in Budd-Chiari syndrome.Smalberg 2012 meta-analysis
JAK2 V617F screening of patients without typical blood features of a myeloproliferative neoplasm identified one in 17.1% of screened Budd-Chiari and 15.4% of portal vein thrombosis patients.Smalberg 2012 meta-analysis
Among 518 patients with a myeloproliferative neoplasm and splanchnic vein thrombosis, median age was 44 years, women were over-represented and PV was the most frequent diagnosis (37.1%).Sant'Antonio 2020
Splanchnic veins account for 14.5% of all thromboses in PV and the cerebral venous sinus for 2.7%, per the JAMA review.JAMA review 2025
BSH gives the incidence of splanchnic vein thrombosis during the course of PV as 0.8% to 7.8%.BSH 2019 guideline, specific situations

Masked disease: normal or borderline hemoglobin

An international study described 140 patients with JAK2 V617F and PV bone marrow morphology whose hemoglobin was 16.0 to 18.4g/dL in men and 15.0 to 16.4g/dL in women.Masked PV study (Barbui 2014)
Compared with 257 patients with overt PV, that masked group had more men, more thrombocytosis and a more frequent history of arterial thrombosis.Masked PV study (Barbui 2014)
A summary of the 2016 WHO criteria cites a study of 118 patients with masked PV in which 72% had a previous arterial or venous thrombosis.WHO 2016 criteria summary (Barbui 2018)
In a Turkish series, 23 of 208 patients with a classical myeloproliferative disease (11%) had microcytosis with hemoglobin and hematocrit that were not raised, and iron deficiency was the apparent cause in 15.Aladağ 2019
All 20 of those patients tested carried JAK2 V617F, and the red cell count was raised in 17 of 23 (73.9%).Aladağ 2019
Marked splenomegaly can dilute the blood and understate hemoglobin and hematocrit in some patients, Mayo Clinic and Italian authors note.Tefferi, Vannucchi and Barbui 2021

Who is affected

Median age at diagnosis was 61 years in the international study, with 10% of patients younger than 40.International PV study (Tefferi 2013)
The JAMA review gives a median age at diagnosis of 65 years and a male to female incidence ratio of 1.3 to 1.6.JAMA review 2025
The same review estimates an annual US incidence of 0.5 to 4.0 per 100,000 people and about 65,000 people living with PV.JAMA review 2025
Patients with a JAK2 exon 12 mutation usually present with predominant erythropoiesis, a subnormal erythropoietin level and a younger age at diagnosis.ICC 2022 criteria (Gianelli 2023)

Polycythemia vera is often mistaken for

Diagnoses patients commonly carry first, and why the sources say they are confused.

First diagnosis	Why it is confused
Secondary polycythemia from smoking or lung disease	The JAMA review lists tobacco smoking and cyanotic heart disease among causes of raised erythropoietin. BSH puts erythrocytosis in 6% to 8% of people with advanced COPD.BSH 2019 guideline, specific situations
Sleep apnea	Erythrocytosis is uncommon in sleep apnea: 1.6% of 1604 veterans evaluated for it had clinical erythrocytosis, and apnea severity did not predict hematocrit.Nguyen and Holty 2017
Testosterone or anabolic steroid effect	A testosterone gel label warns of polycythemia, and hematocrit rose above 0.50 in 11% of 1073 trans men on testosterone. The JAMA review also names androgens taken for athletic performance.Madsen 2021
SGLT2 inhibitor effect	Median hematocrit rose 2.8% on empagliflozin in pooled trials on its label, and a Mayo Clinic and University of Montreal update calls erythrocytosis with this drug class increasingly recognized.Jardiance label
Relative or spurious polycythemia	A contracted plasma volume with a normal red cell mass raises hemoglobin and hematocrit; the JAMA review says this form is generally not persistent.JAMA review 2025
Essential thrombocythemia	Thrombocytosis was the most frequent blood count finding in masked PV, and the WHO 2016 summary warns that mistaking it for essential thrombocythemia means phlebotomy is not considered.WHO 2016 criteria summary (Barbui 2018)
Iron deficiency with a normal blood count	Iron deficiency with a low mean cell volume may keep hematocrit from rising and mask PV, as a Turkish series of 23 such patients reported.Aladağ 2019
Itch of unknown cause	Aquagenic itch preceded diagnosis by an average of 2.9 years in a German survey, and led to a hematological investigation in only 15.4%.Siegel 2013
Stroke from atherosclerosis or another evident cause	In a French registry, 51% of patients whose stroke revealed a myeloproliferative neoplasm had another stroke mechanism as well, such as atherosclerosis.Ong 2016
Splanchnic clot put down to another risk factor	In a 518-patient study, 38.6% of patients with a neoplasm-related splanchnic clot also had another hypercoagulable disorder.Sant'Antonio 2020
Idiopathic erythrocytosis	The first report of JAK2 exon 12 mutations found them in patients who had been given a diagnosis of idiopathic erythrocytosis or V617F-negative PV.Scott 2007
Hereditary erythrocytosis, including high oxygen affinity hemoglobin	Mayo Clinic and University of Montreal authors say hereditary erythrocytosis should be considered when erythrocytosis is longstanding and there is a family history.Gangat, Szuber and Tefferi 2025
Erythrocytosis from a kidney or liver tumor	The JAMA review names renal cell carcinoma and hemangioblastoma as erythropoietin sources. A 7-year retrospective study found paraneoplastic erythrocytosis in 4.5% of 378 patients with hepatocellular carcinoma.Burciu 2024
Erythrocytosis after kidney transplant	BSH puts the incidence of erythrocytosis after kidney transplantation between 5% and 20%, typically within the first year.BSH 2019 guideline, specific situations

Codes patients often carry before this diagnosis

For spotting the pattern in a problem list or registry. Descriptions are checked daily against NLM's ICD-10-CM service; this is not coding advice.

Secondary polycythemia D75.1

The JAMA review says PV should be distinguished from secondary erythrocytosis caused by smoking, sleep apnea, tumors or androgens.JAMA review 2025

Budd-Chiari syndrome, or portal vein thrombosis I82.0, I81

A meta-analysis found JAK2 V617F in 41.1% of Budd-Chiari and 27.7% of portal vein thrombosis patients.Smalberg 2012 meta-analysis

Other pruritus, or pruritus, unspecified L29.89, L29.9

Aquagenic itch preceded the diagnosis of PV by an average of 2.9 years in a German survey.Siegel 2013

Erythromelalgia I73.81

The JAMA review reports erythromelalgia in 5.3% of patients with PV.JAMA review 2025

Splenomegaly, not elsewhere classified R16.1

A palpable spleen was found in 36% of evaluable patients at diagnosis in the international study.International PV study (Tefferi 2013)

Cerebral infarction, unspecified, or acute myocardial infarction, unspecified I63.9, I21.9

Myocardial infarction and ischemic stroke were the most frequent vascular events before diagnosis in a 612-patient study.Enblom 2015

Essential (hemorrhagic) thrombocythemia, or thrombocytosis, unspecified D47.3, D75.839

Thrombocytosis was the most frequent blood count finding in masked PV, which may be mistaken for essential thrombocythemia.WHO 2016 criteria summary (Barbui 2018)

Obstructive sleep apnea (adult) (pediatric) G47.33

Only 1.6% of 1604 veterans evaluated for sleep apnea had clinical erythrocytosis, and apnea severity did not predict it.Nguyen and Holty 2017

Familial erythrocytosis D75.0

Hereditary erythrocytosis is considered when erythrocytosis is longstanding with a family history, per Mayo Clinic and University of Montreal authors.Gangat, Szuber and Tefferi 2025

Testing for Polycythemia vera, step by step

The testing order the cited guidance describes, by who it applies to. It summarizes published guidance and is not a plan for any one patient.

Anyone with hemoglobin or hematocrit above the thresholds

Review earlier blood counts
Mayo Clinic and University of Montreal authors say a historical overview of hematocrit and hemoglobin helps separate longstanding from acquired erythrocytosis. The JAMA review treats erythrocytosis as sustained when it typically lasts 3 months or longer.Gangat, Szuber and Tefferi 2025

Anyone with erythrocytosis

History for secondary causes
The JAMA review lists cyanotic heart disease, tobacco smoking, obstructive sleep apnea, high altitude, erythropoietin-secreting tumors and exogenous androgens or erythropoietin. An ASH education review adds SGLT2 inhibitors and testosterone as common drug causes.JAMA review 2025

Patients with suspected PV

JAK2 V617F on peripheral blood
Mayo Clinic and Italian authors make JAK2 mutation screening the first step and favor testing exons 14 and 12 upfront. They note that peripheral blood and bone marrow samples are equally informative.Tefferi, Vannucchi and Barbui 2021

Patients with suspected PV, alongside JAK2 testing

Serum erythropoietin
The same authors recommend measuring erythropoietin together with JAK2. A subnormal level is the minor criterion in the WHO and ICC criteria.Tefferi, Vannucchi and Barbui 2021

Patients with erythrocytosis, and patients with unusual clots

The JAMA review's order
The JAMA review advises JAK2 testing for patients with erythrocytosis and a low erythropoietin level. It advises the same test for all patients with thrombosis in the splanchnic veins or cerebral sinus.JAMA review 2025

Patients negative for JAK2 V617F in whom PV is still suspected

Assay sensitivity and JAK2 exon 12
The ICC criteria recommend highly sensitive JAK2 V617F assays, with a sensitivity level under 1%. In negative cases they advise considering non-canonical or atypical JAK2 mutations in exons 12 to 15.ICC 2022 criteria (Gianelli 2023)

Patients with erythrocytosis and a JAK2 result

Apply the WHO or ICC criteria
Both sets have 3 major criteria: raised hemoglobin or hematocrit, bone marrow biopsy showing panmyelosis with pleomorphic mature megakaryocytes, and JAK2 V617F or an exon 12 mutation. Diagnosis needs all 3, or the first 2 plus a subnormal erythropoietin level.ICC 2022 criteria (Gianelli 2023)

Laboratories that still measure red cell mass

Where WHO and ICC differ
The ICC keeps red blood cell mass more than 25% above the mean normal predicted value as an alternative to hemoglobin or hematocrit. The WHO 5th edition removed chromium-51 red cell mass as a criterion because it has become uncommon in practice.WHO 5th edition (Khoury 2022)

Patients being confirmed as PV

Bone marrow biopsy
Biopsy is a major criterion in both sets of criteria. Mayo Clinic and Italian authors advise it in all patients except some older patients and those with significant comorbidities, to confirm the diagnosis and obtain cytogenetic information.Tefferi, Vannucchi and Barbui 2021

Men with hemoglobin above 18.5g/dL or women above 16.5g/dL

When biopsy may be omitted: ICC wording
The ICC says biopsy may not be required with sustained absolute erythrocytosis at these levels, hematocrit above 55.5% in men or 49.5% in women, and a JAK2 V617F or exon 12 mutation.ICC 2022 criteria (Gianelli 2023)

The same hemoglobin and hematocrit levels

When biopsy may be omitted: WHO 2016 wording
The 2016 WHO criteria allow this only if the JAK2 mutation and a subnormal erythropoietin level are both present. The 2022 summary paper of the WHO 5th edition does not print this footnote. They add that initial myelofibrosis, present in up to 20% of patients, can only be detected by biopsy.WHO 2016 criteria summary (Barbui 2018)

Men with hematocrit above 52% or women above 48%

A simpler rule tested in one study
In 287 patients studied by a Barcelona group, this hematocrit plus JAK2 V617F had 79% sensitivity and 97% specificity for PV. Adding a low erythropoietin level or the allele burden alone did not improve accuracy, and adding both raised sensitivity to 83%.Ancochea 2014

JAK2-positive patients where PV and essential thrombocythemia are both possible

JAK2 V617F allele burden
Mayo Clinic and Italian authors say the allele burden may give an additional clue. They expect it to be higher in PV and often under 20% in JAK2-mutated essential thrombocythemia.Tefferi, Vannucchi and Barbui 2021

Adults with primary thrombosis of the portal venous system or hepatic outflow tract

JAK2 testing after a splanchnic clot
Baveno VII recommends searching for a myeloproliferative neoplasm by JAK2 V617F testing in all such adults. If that is negative, it advises considering calreticulin and JAK2 exon 12 mutations and next-generation sequencing.Baveno VII consensus

Adults with primary splanchnic vein thrombosis and no driver mutation

Bone marrow biopsy after a splanchnic clot
Baveno VII says biopsy should be discussed with hematologists to rule out a myeloproliferative neoplasm, irrespective of blood cell counts.Baveno VII consensus

Patients with unexplained secondary polycythemia

Oxygen saturation and sleep studies
The Stanford authors of a 1604-veteran study suggest nocturnal oximetry may help in unexplained secondary polycythemia. They add that polysomnography may be warranted with unexplained nocturnal hypoxemia.Nguyen and Holty 2017

Patients with JAK2-unmutated erythrocytosis

Work-up when JAK2 is negative
An ASH education review uses the oxygen tension at 50% hemoglobin saturation (p50) to separate high oxygen affinity hemoglobin variants from oxygen-sensing pathway mutations. A subnormal erythropoietin level suggests an erythropoietin receptor mutation.ASH education review 2025

Patients with confirmed PV

Cytogenetics and gene panels
Mayo Clinic and Italian authors say next-generation sequencing for other mutations and cytogenetic testing are more useful for prognosis than for diagnosis.Tefferi, Vannucchi and Barbui 2021

Where testing goes wrong

JAK2 V617F does not separate PV from related diseases; it is also detected in 50% to 70% of patients with essential thrombocythemia or primary myelofibrosis.Tefferi, Vannucchi and Barbui 2021
A Danish population study using droplet digital PCR found JAK2 V617F in 3.1% of 19,958 adults, a prevalence its authors call 3 to 30 times higher than with less sensitive methods.Cordua 2019
Only 16 of the 645 participants positive for JAK2 V617F or a calreticulin mutation in that study had a myeloproliferative neoplasm at baseline.Cordua 2019
An earlier Copenhagen general population study of 49,488 people found the mutation in 0.1%.Nielsen 2013
A negative JAK2 V617F result does not exclude PV: other JAK2 mutations accounted for 3% of screened patients in the international study.International PV study (Tefferi 2013)
Exon 12 mutations were frequently present at low levels in granulocyte DNA in the report that first described them.Scott 2007
Published shares for JAK2 V617F in PV vary: 95% in the international study and an estimated 97% in the ICC authors' paper, which assigns the other 3% to activating JAK2 mutations including exon 12.ICC 2022 criteria (Gianelli 2023)
A normal erythropoietin level does not exclude PV; it was subnormal in 81%, normal in 17% and raised in 2% of 1058 patients tested.International PV study (Tefferi 2013)
In a French study of patients with absolute erythrocytosis, 87% of those with PV had erythropoietin below the normal range, a result with 97% specificity.Mossuz 2004
At a Canadian tertiary center, low erythropoietin had a sensitivity of 0.77 and specificity of 0.98 for JAK2-mutant erythrocytosis among 213 patients tested.Senecal 2025
Many people meet the 2016 threshold: 7.6% of men and 0.4% of women in the Dutch Lifelines cohort met the WHO 2016 definition of erythrocytosis.Lifelines cohort (Wouters 2020)
Hemoglobin and hematocrit below the thresholds do not exclude PV when iron deficiency and microcytosis are present.Aladağ 2019
The authors of the 2016 WHO summary write that lowering the thresholds revealed that PV had been underdiagnosed in the past.WHO 2016 criteria summary (Barbui 2018)
A sleep apnea diagnosis may not explain erythrocytosis; in 1604 veterans hematocrit tracked awake and nocturnal oxygen saturation, not the apnea-hypopnea index.Nguyen and Holty 2017
Mayo Clinic and University of Montreal authors call excluding PV by JAK2 mutation screening of exons 12 to 15 the foremost step in erythrocytosis; the same update lists testosterone and SGLT2 inhibitors among acquired causes.Gangat, Szuber and Tefferi 2025
The testosterone gel label says to check hematocrit before starting, again at 3 to 6 months and then annually, and to stop therapy if hematocrit becomes elevated.Testosterone gel 1.62% label
An evident stroke cause does not exclude a myeloproliferative neoplasm; the French registry authors advise attention to blood counts even in patients with obvious stroke etiologies.Ong 2016
JAK2 V617F is rare in unselected stroke: 46 of 10,428 patients (0.4%) in a Chinese ischemic stroke cohort carried it.Zhao 2026
Baveno VII states that identifying one risk factor for splanchnic vein thrombosis does not deter from a complete work-up.Baveno VII consensus
Skipping the biopsy misses early fibrosis: the ICC authors report mild reticulin fibrosis in about 20% of cases at diagnosis, linked to later myelofibrosis.ICC 2022 criteria (Gianelli 2023)
The WHO and ICC wording differs on when biopsy may be omitted, and a 2023 Mayo Clinic and Italian review describes bone marrow confirmation as advised but not mandated.Tefferi and Barbui 2023
Erythropoietin does not sort idiopathic erythrocytosis; BSH says levels are below normal in a third of such patients and elevated in two-thirds.BSH 2019 guideline, specific situations
An Italian review suggests that masked PV may carry a worse outcome possibly owing to missed or delayed diagnoses and less intensive treatment.Iurlo 2020

Where to test

NIH Genetic Testing Registry: acquired polycythemia vera: NCBI E-utilities listed 65 tests for this condition (MedGen concept C0032463) on November 12, 2026, including JAK2 tests. NIH does not independently verify submissions or endorse any laboratory.NIH GTR
JAK2 V617F and exon 12 testing through clinical laboratories: Mayo Clinic and Italian authors note that peripheral blood and bone marrow samples are equally informative for detecting and quantifying JAK2 V617F.Tefferi, Vannucchi and Barbui 2021
Bone marrow biopsy with hematopathology review: The 2016 WHO summary cites a blinded review in which the characteristic bone marrow features of PV were reproducible, with interobserver agreement of almost 93%.WHO 2016 criteria summary (Barbui 2018)

Family screening and referral

Who else in the family

JAK2 variants in PV are acquired, not inherited, though the JAMA review notes an approximately 5-fold risk of PV among first-degree relatives.JAMA review 2025
In Swedish registries covering 24,577 first-degree relatives of 11,039 patients, relatives had a relative risk of 5.7 for PV, with consistently higher risks for siblings.Landgren 2008
That study found no difference in age at diagnosis between affected relatives of patients and of controls, and no support for anticipation.Landgren 2008
Longstanding erythrocytosis with a positive family history points instead to hereditary erythrocytosis, which Mayo Clinic and University of Montreal authors list with its germline causes.Gangat, Szuber and Tefferi 2025
BSH notes that congenital erythrocytosis is usually diagnosed in children or young adults, often with a family history of erythrocytosis.BSH 2019 guideline, specific situations

Who to refer to

Erythrocytosis is a common reason for referral to hematology services and is usually secondary in origin, the Lifelines authors note.Lifelines cohort (Wouters 2020)
Baveno VII recommends close collaboration with subspecialists for the work-up of splanchnic vein thrombosis without cirrhosis, and discussing bone marrow biopsy with hematologists.Baveno VII consensus
BSH recommends JAK2 V617F testing for patients presenting with splanchnic vein thrombosis not associated with local malignancy.BSH 2019 guideline, specific situations
BSH also recommends that patients with PV and splanchnic vein thrombosis be managed in a multidisciplinary setting with interventional radiology and hepatology.BSH 2019 guideline, specific situations
For erythrocytosis from hypoxic lung disease, BSH says patients should be evaluated by a respiratory physician, and those with sleep apnea referred for investigation.BSH 2019 guideline, specific situations
The German stroke group calls for high clinical awareness of an underlying neoplasm in stroke patients with sustained, abnormal blood count findings.Stefanou 2019
A 4-question aquagenic pruritus questionnaire from German dermatology and hematology centers reached 97.3% sensitivity and 79.5% specificity for an associated myeloproliferative neoplasm.Witte 2025
When the work-up is negative but suspicion of hereditary erythrocytosis is high, Mayo Clinic and University of Montreal authors recommend an expanded next-generation sequencing panel.Gangat, Szuber and Tefferi 2025
After diagnosis, the JAMA review says thrombosis risk should be assessed; guidelines define high risk as age 60 or older or a prior thrombosis.JAMA review 2025

Find a specialist by state

From the CMS NPI Registry, a public directory of US clinicians by registered specialty. A listing is not an endorsement and says nothing about experience with Polycythemia vera; patient organizations and academic centers can often name experienced clinicians.

ICD-10-CM codes for Polycythemia vera

For orders, referrals and prior authorization. Each code is checked daily against NLM's ICD-10-CM service.

D45Polycythemia veraCurrent in NLM's ICD-10-CM listNLM ICD-10-CM lookup

Once the diagnosis is confirmed

Polycythemia vera drugs for prescribers3 prescribing guides, side by side: Besremi, Jakafi, Mimrylo.Open trials: 55Screen a de-identified patient against every recruiting Polycythemia vera study on ClinicalTrials.gov.Patient and family pageThe plain-language Polycythemia vera page, with trials, treatments and help paying.

For the patient: why your doctor ordered this test

Plain language a patient can read or take home.

Your doctor ordered these tests because a blood count showed more red blood cells than expected, or because of a symptom such as itching after a bath or shower, or a blood clot in an unusual place.

Most people with a high red cell count do not have polycythemia vera. Smoking, sleep apnea, lung disease, testosterone and some diabetes medicines can all raise the count. One less common cause is polycythemia vera, a slow-growing blood cancer in which the bone marrow makes too many red blood cells.

A blood test looks for a change in a gene called JAK2, which is found in almost everyone with polycythemia vera. This change happens in blood cells during life and is not passed on to children. A second blood test measures a hormone called erythropoietin, which is usually low in this condition. Your doctors or health care professionals may also suggest a bone marrow biopsy.

These results are read together. A high count by itself, or a JAK2 change by itself, is not enough for the diagnosis. Tell your doctor about any medicines, hormones or supplements you take, and about any blood clots you have had.

Questions clinicians ask about Polycythemia vera testing

Which combinations of findings should prompt testing for polycythemia vera?

In published screening and biopsy studies, the highest yields came from erythrocytosis plus serum erythropoietin below the normal range (97.8% of 186 patients with absolute erythrocytosis who had erythropoietin measured in 8 French hospital centers, 116 of them with polycythemia vera), and from budd-Chiari syndrome plus JAK2 V617F testing (41.1% of 1062 patients with Budd-Chiari syndrome pooled in a meta-analysis). Among patients already diagnosed, the most common combination began with erythrocytosis, seen in 98% of 1268 patients screened for JAK2 mutations among 1545 with polycythemia vera in a 7-center international study. These figures describe study groups, not any one patient's chance of having polycythemia vera.

What are the WHO and ICC diagnostic criteria for polycythemia vera?

Both use hemoglobin above 16.5g/dL in men or 16.0g/dL in women, or hematocrit above 49% or 48%, as the first of 3 major criteria. The other 2 are a bone marrow biopsy showing age-adjusted hypercellularity with trilineage growth and pleomorphic mature megakaryocytes, and JAK2 V617F or a JAK2 exon 12 mutation. Diagnosis requires all 3 major criteria, or the first 2 plus the minor criterion of a subnormal serum erythropoietin level. The ICC also accepts a red blood cell mass more than 25% above the mean normal predicted value, while the WHO 5th edition removed chromium-51 red cell mass as a criterion.

When can bone marrow biopsy be omitted in suspected polycythemia vera?

Above 18.5g/dL hemoglobin in men or 16.5g/dL in women (hematocrit above 55.5% or 49.5%), the criteria say a biopsy may not be required. The ICC wording asks for sustained absolute erythrocytosis at those levels plus a JAK2 V617F or exon 12 mutation. The 2016 WHO wording also requires a subnormal erythropoietin level, and notes that initial myelofibrosis, present in up to 20% of patients, can only be detected by biopsy. Mayo Clinic and Italian authors advise biopsy in all patients except some who are older or have significant comorbidities (Tefferi 2021).

How often is JAK2 positive in polycythemia vera, and when is exon 12 tested?

About 98% of screened patients carried a JAK2 mutation in a 1545-patient international study, V617F in 95% and other JAK2 mutations in 3% (Tefferi 2013). The ICC authors estimate 97% for V617F and 3% for other activating JAK2 mutations, including exon 12. The ICC criteria recommend assays with a sensitivity level under 1% and, in negative cases, considering mutations in exons 12 to 15. JAK2 V617F is not specific to PV: it is also found in 50% to 70% of essential thrombocythemia and primary myelofibrosis (Tefferi 2021).

How useful is serum erythropoietin in diagnosing polycythemia vera?

Erythropoietin was subnormal in 81% of 1058 patients with PV who were tested, normal in 17% and raised in 2% (Tefferi 2013). In a French study of absolute erythrocytosis, a level below the normal range had 97% specificity and a 97.8% positive predictive value for PV (Mossuz 2004). A Barcelona study found that hematocrit plus JAK2 V617F already gave 79% sensitivity and 97% specificity, and adding erythropoietin alone did not improve accuracy (Ancochea 2014). A subnormal level remains the minor criterion in the WHO and ICC criteria.

How is polycythemia vera separated from secondary erythrocytosis?

Over 95% of patients with PV have a JAK2 variant, which the JAMA review says helps distinguish it from secondary causes such as tobacco smoking or sleep apnea. That review adds that spurious and secondary erythrocytosis are not associated with pruritus, leukocytosis or thrombocytosis. In the Dutch Lifelines cohort, all 7 people with erythrocytosis and JAK2 V617F also had leukocytosis or thrombocytosis (Wouters 2020). Drug causes include testosterone and SGLT2 inhibitors, and Mayo Clinic and University of Montreal authors call JAK2 mutation screening the foremost step in the work-up (Gangat 2025).

Should patients with Budd-Chiari syndrome or portal vein thrombosis be tested for JAK2?

JAK2 V617F was found in 41.1% of patients with Budd-Chiari syndrome and 27.7% with portal vein thrombosis in a meta-analysis of 1062 and 855 patients (Smalberg 2012). Screening patients without typical blood features of a myeloproliferative neoplasm still identified one in 17.1% and 15.4%. Baveno VII recommends JAK2 V617F testing in all adults with primary splanchnic vein thrombosis, and BSH recommends it when the clot is not associated with local malignancy. The JAMA review advises the same for cerebral sinus thrombosis.

How often does a clot come before the diagnosis of polycythemia vera?

Arterial thrombosis was recorded before or at diagnosis in 16% and venous thrombosis in 7.4% of 1545 patients (Tefferi 2013). In a 612-patient study of myeloproliferative neoplasms from Sweden, Denmark and France, 25% had a vascular complication before diagnosis, and 44% had blood counts meeting diagnostic criteria at least 3 months earlier (Enblom 2015). Fifty of those patients had a vascular complication between the abnormal blood test and the diagnosis.

What is the ICD-10 code for polycythemia vera?

The ICD-10-CM code is D45, Polycythemia vera, per the National Library of Medicine's ICD-10-CM lookup checked November 12, 2026. Secondary polycythemia is coded separately as D75.1 and familial erythrocytosis as D75.0.

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A reference for licensed professionals, checked against its sources on November 12, 2026. It summarizes what the cited guidance says and does not tell anyone how to diagnose or treat a specific patient. Guidelines change; the current guideline and the treating clinician's judgment govern. Trial Friend is an independent information service, not a medical provider.