Systemic mastocytosis (SM) is a rare progressive blood disorder that involves excessive mast cell activity that triggers mild-to-severe allergic reactions.
An important part of disease management includes regular blood tests to monitor disease progression and the effectiveness of the treatment protocol. It allows your health care team to proactively adjust your medication to better treat symptoms and protect against potential complications.
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.
SM diagnostic tests
A diagnosis of systemic mastocytosis relies on symptom history, blood and urine tests, bone scans, ultrasounds, X-rays, bone marrow biopsy and internal biopsies of such organs as the liver or the gastrointestinal tract.
Read more about SM treatment and care
Over time, the excessive mast cell activity and allergic reactions affect the internal organs, causing them to deteriorate and affecting quality of life. For example, the effect of sustained abnormal mast cell activation in the gastrointestinal tract can lead to peptic ulcers.
The mildest form of SM is indolent systemic mastocytosis, but it can progress to other, more aggressive forms of the disease, such as smoldering systemic mastocytosis and aggressive systemic mastocytosis. These forms of SM have a high symptom burden and a greater risk of complications, as well as reduced life expectancy.
The results of diagnostic tests are used as a baseline and compared to regular monitoring of blood, urine and mast cell levels in the connective tissue, bones and internal organs.
Disease management of SM by monitoring the blood
As there is currently no cure for SM, the therapeutic focus is on avoiding symptom triggers, managing the symptom burden and slowing disease progression. Your health care team will regularly monitor your blood tests to inform how they manage your SM medication and treatment. Certain markers can also help predict life expectancy.
Your doctors are monitoring the following key elements when they check your blood results.
- Elevated tryptase levels in the blood are used in diagnosing SM. Levels of 20 ng/mL or higher are a diagnostic criterion. They indicate high mast cell activity. If levels go up or down, it is an indicator of whether or not treatment is working and if the disease is progressing. If levels do increase, this may require an adjustment to your medication.
- A complete blood count keeps track of the number of mast cells in the blood. Anemia and low platelet counts may require transfusion.
- Low vitamin D or iron levels may indicate malabsorption-related deficiencies or bone marrow dysfunction.
Following an event of anaphylaxis shock, a blood test will also be required to measure tryptase levels.
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