Mayo Clinic Laboratories > Immunology > Mast cell activation syndrome

Mast cell activation syndrome

Simplified, noninvasive testing for a complex disease

Mast cell activation syndrome (MCAS) is a rare, multisystem disorder characterized by an aberrant activation of mast cells that triggers them to excessively release chemical mediators. Diagnosing MCAS, which affects each patient uniquely, relies on a combination of the major and two minor diagnostic criteria set forth by the World Health Organization.1 These include:

  • Major criteria: Presence of clinical signs of severe, recurrent systemic MCA (often in the form of anaphylaxis and involving at least two organ systems).
  • Minor criteria: Increased serum tryptase levels from baseline to 20% + 2 ng/mL.
  • Minor criteria: Therapeutic response to medications that stabilize MC; medications directed against MC mediator production, or drugs blocking mediator release of the effects of MC-derived mediators.

Due to the lack of access to or limitations of traditional diagnostic approaches, affected patients often experience lengthy diagnostic odysseys. An alternative, simplified strategy to diagnose MCAS is to measure urine mediators. Used to complement conventional diagnostic tools, urine mediator quantitation can provide answers to support diagnosis and guide care.2

~30 years

~30 years on average to diagnose MCAS from time of symptom onset3

~6 in 100,000

~6 in 100,000 individuals are affected by MCAS4

Mast cell mediator testing

Urine mediator testing Urine mediator testing

Urine mediator testing

Serum tryptase is the most common MCAS mediator and one of the established diagnostic criteria. The use of serum tryptase to diagnose MCAS, however, has several disadvantages. This includes requirements that the blood sample collection occurs within one to four hours of the suspected disease flare, and both baseline and acute measurements are needed for diagnosis. For many patients, receiving blood tests at the right time is not possible. In other instances, serum tryptase levels may be inconclusive or result as normal despite symptom presentation.

Quantifying validated mast cell mediators in urine is a simplified alternative to confirm MCAS diagnosis. Urine mediator testing is not only noninvasive, but the increased stability of mediators in urine allows for mediator measurement in randomly collected specimens. Test results can help physicians and healthcare professionals confidently diagnose patients, select the best treatment, and monitor treatment efficacy. Mayo Clinic Laboratories offers the most robust portfolio of MCAS urine mediator testing commercially available, enabling clarity on a complex diagnosis.

Panel testing

Individual testing

Read more The Utility of Measuring Urinary Metabolites of Mast Cell Mediators in MCAS
Learn more Mast cell activation disease overview
References
  1. Valent P, Akin C, Hartmann K, et al. Updated Diagnostic Criteria and Classification of Mast Cell Disorders: A Consensus Proposal. Hemasphere. 2021 Oct 13;5(11):e646. doi:10.1097/HS9.0000000000000646. PMID: 34901755; PMCID: PMC8659997.
  2. Butterfield J, Weiler CR. The utility of measuring urinary metabolites of mast cell mediators in systemic mastocytosis and mast cell activation syndrome. J Allergy Clin Immunol Pract. 2020 Sep;8(8):2533-2541. doi:10.1016/j.jaip.2020.02.021. Epub 2020 Mar 3. PMID: 32142966.
  3. Afrin LB, Self S, Menk J, Lazarchick J. Characterization of mast cell activation syndrome. Am J Med Sci. 2017 Mar;353(3):207-215. doi:10.1016/j.amjms.2016.12.013. Epub 2016 Dec 16. PMID: 28262205; PMCID: PMC5341697.
  4. Akin C. Dilemma of mast cell activation syndrome: overdiagnosed or underdiagnosed? J Allergy Clin Immunol Pract. Volume 12, Issue 3, 762–763.
INTERESTED IN LEARNING MORE?

Fill out the form below and one of our specialists will be in touch.

Are you a patient? Click here.