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JAK2 mutation test

Also called: JAK2 V617F

The JAK2 test looks for a gene change found in most people with polycythemia vera and some other bone marrow disorders.

SampleA small tube of blood from a vein in your arm
Fasting?Usually not needed
Results1 to 2 weeks
Good to knowOne result rarely tells the whole story. Your provider looks at your results together with your symptoms, exam, and other tests.

What the test is

It's done on blood.

Why it's done

  • High hemoglobin or hematocrit without a clear cause
  • Very high platelets
  • Unusual blood clots

Getting ready and what happens

  • None.

How the test is done

  • A health worker cleans the skin, puts a band around your arm, and draws blood from a vein with a small needle. It takes a few minutes.

What the results mean

Positive

Supports a myeloproliferative disorder; a blood specialist guides treatment.

Questions to ask your provider

  • What do my results mean for me?
  • Do I need to repeat this test or have other tests?

Risks

A blood draw is very safe. You may have slight pain or a small bruise where the needle went in.

Related conditions

Related tests

Sources

Last updated 2026-11-13.