How Is Systemic Mastocytosis Diagnosed? The Tests Explained

Welcome to the latest episode of the Allergy, Asthma & Immunology Innovations podcast. This episode covers the tests used to diagnose systemic mastocytosis (SM), a mast cell disease. For some people, it can take years to get a correct diagnosis, but there are new tests that can help shorten the time. 

Co-hosts Payel Gupta, MD, an allergist and immunologist, and patient advocate Kortney are joined by Anthony (Tony) Hunter, MD, a hematologist at Winship Cancer Institute of Emory University in Atlanta. They review each of the available SM tests, what they can and cannot tell you, and what happens after a diagnosis.

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Listen to Diagnosing Systemic Mastocytosis Podcast

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Thank you to Blueprint Medicines for supporting this podcast episode.

This podcast is for informational purposes only and does not substitute professional medical advice. Any mention of brands is also informational and not an endorsement. Always consult with your healthcare provider for any medical questions or concerns.

Key Takeaways About Diagnosing Systemic Mastocytosis (SM)

Due to misdiagnosis or delayed diagnosis, it can take patients on average about 8 years to get formally diagnosed with systemic mastocytosis.

  • What does a high tryptase level mean? Mast cells release tryptase. Many people with mastocytosis have high tryptase even on a good day. But a normal level does not rule out having SM.
  • What is HαT? About 6 out of 100 people have extra copies of the tryptase gene. This is called hereditary alpha-tryptasemia, or HαT. It is the most common reason for high tryptase. A simple blood test can now check for it.
  • What is the KIT D816V test? Most people with mastocytosis have this gene change. It works like a light switch stuck in the “on” position. Some tests are more sensitive than others, so ask which test was used.
  • Why get a bone marrow biopsy to diagnose SM? It is the main test to confirm the diagnosis. The bone marrow is where you can see the most mast cells. 
  • Do urine tests help? Urine tests can show that mast cells are active. But they are not used to diagnose systemic mastocytosis. They can be hard to collect, and insurance may not cover them.

Timestamps for the Podcast about Diagnosing Systemic Mastocytosis

01:23 — Why see a hematologist for mast cell disease

04:38 — Why diagnosis takes so long

06:39 — What tryptase is and how it’s used

09:33 — What is hereditary alpha-tryptasemia (HαT)

12:50 — What is the KIT D816V mutation

19:07 — Why a bone marrow biopsy is the key test

20:55 — What a bone marrow biopsy is like

26:20 — Are urine tests helpful

29:48 — What happens after a diagnosis

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