An accurate diagnosis of systemic mastocytosis (SM) requires a comprehensive consultation and review of symptoms and medical history before moving onto blood and urine tests, imaging, bone density scans, and skin, organ or bone marrow biopsies.
Key indicators of an SM diagnosis are elevated tryptase levels in the blood, which indicate mast cell activation.
What is SM?
Systemic mastocytosis (SM) is a rare hematological disease characterized by mast cells that are overactive and accumulate in different parts of the body such as the bone marrow, liver, spleen, gastrointestinal tract and lymph nodes.
What is tryptase?
Tryptase is a type of protein or enzyme found in mast cells. Mast cells release it—along with histamines, leukotrienes and prostaglandins—into the bloodstream during an inflammatory response.
Read more about SM testing and diagnosis
The chemicals are responsible for the allergic reaction in the body that activates SM symptoms such as skin itching, flushing, hives, fatigue, headaches, depression, brain fog, nausea, vomiting, diarrhea, stomach pain, bone and joint pain and anaphylaxis.
Following an unexplained anaphylaxis reaction or when a mast cell disorder is suspected, clinicians will perform a tryptase test.
Diagnostic tests in SM
SM has many common symptoms that overlap with other conditions, and it can often take some time before clinicians perform the right diagnostic tests.
SM can be mistaken for a number of different conditions, including skin conditions, mast cell activation syndromes, endocrine disorders, gastrointestinal disorders and allergies.
To ensure an accurate diagnosis, your doctor will conduct some or all of the following diagnostic procedures.
- A full symptom history to see if the symptom burden corresponds with SM.
- Blood testing for a full blood count, tryptase test and to measure mast cell mediators.
- Urine testing to measure mast cell mediators.
- Ultrasound to check for an enlarged spleen or liver.
- Bone density X-ray to check for bone fragility and potential osteoporosis.
- Skin or organ biopsy to measure mast cell abundance.
- Bone marrow biopsy to measure the density of mast cells in the bone marrow, where they are produced.
- Genetic testing to check for the KIT D816V mutation that is the origin of SM.
The importance of measuring and monitoring tryptase levels
An elevated tryptase level is essential to confirm a diagnosis of SM. It can also determine the subtype of the disorder, with a high level of tryptase found in smoldering systemic mastocytosis (SSM).
Regular monitoring of tryptase levels in people living with SM is useful in tracking whether or not treatment is effective in managing the disorder or delaying disease progression. If the levels rise, it may indicate that the disease is progressing to another SM subtype.