Knowledge Check

Sort the tests (top) according to whether they should be ordered as first-line tests in all patients with polycythemia, as second line tests according to symptoms, or not at all (bottom):

Serum ferritin

Echocardiogram

TSH

Serum EPO

Reticulocyte count

Abdominal/pelvic imaging

Sleep study

CXR

SaO2

CBC

Cardiac troponin

Liver function

ANA

Jak2 mutation (if PV suspected)

Neuro imaging

Renal function

Liver biopsy

First-line tests

Second-line tests

Not indicated

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Abbreviations: CBC, complete blood count; SaO2, arterial oxygen saturation; EPO, erythropoietin; CXR, chest X ray; TSH, thyroid stimulating hormone; ANA, antinuclear antibody.

True of false: in the primary care setting, where the probability of PV is low, clinical evaluation for secondary causes of erythrocytosis paired with a high erythropoietin level can rule out PV in most patients.

In a young patient with a family history of erythrocytosis in whom first line and second lines studies do not reveal a diagnosis, what 2 tests would you consider:

Name 2 tests

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1. Oxygen dissociation curve to diagnose high-oxygen-affinity hemoglobins
2. Gene sequencing for mutations involving the erythropoietin receptor or oxygen-sensing pathways