Can Mast Cell Activation Syndrome (MCAS) cause elevated Alanine Transaminase (ALT) enzymes while Aspartate Transaminase (AST) and Alkaline Phosphatase (ALP) remain normal?

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From the Guidelines

Yes, Mast Cell Activation Syndrome (MCAS) can potentially cause isolated elevations in Alanine Transaminase (ALT) while Aspartate Transaminase (AST) and Alkaline Phosphatase (ALP) remain within normal ranges. This occurs because mast cells, when inappropriately activated in MCAS, release various inflammatory mediators including histamine, cytokines, and proteases that can affect liver function, as noted in the 2019 report by the aaaai mast cell disorders committee work group 1. The liver contains mast cells, and during MCAS flares, these mediators can cause mild hepatocellular injury that may be reflected primarily in ALT elevations. Some key points to consider include:

  • ALT is more specific to liver damage than AST (which is also found in muscle and other tissues), explaining why ALT might be selectively elevated.
  • Patients with MCAS experiencing liver enzyme abnormalities may benefit from standard MCAS treatments including H1 antihistamines, H2 blockers, and mast cell stabilizers.
  • Monitoring liver enzymes during treatment and avoiding known MCAS triggers is important, as triggers can include hot water, alcohol, drugs, stress, exercise, hormonal fluctuations, infection, and/or physical stimuli, such as pressure or friction, as reported in the study 1.
  • The pattern of isolated ALT elevation without other liver enzyme abnormalities can help differentiate MCAS-related liver involvement from other liver diseases, though other causes of elevated ALT should still be ruled out through appropriate testing. It's also important to note that symptoms of MCAS can be diverse and include abdominal pain, diarrhea, flushing, hypotension, tachycardia, syncope, urticaria, pruritus, and angioedema, among others, as outlined in the study 1.

From the Research

Mast Cell Activation Syndrome and Liver Enzymes

  • Mast Cell Activation Syndrome (MCAS) is a condition characterized by the excessive release of mast cell mediators, leading to various symptoms affecting multiple organ systems.
  • The relationship between MCAS and liver enzymes, such as Alanine Transaminase (ALT), Aspartate Transaminase (AST), and Alkaline Phosphatase (ALP), is not well-established in the provided studies.

Elevated ALT Enzymes in MCAS

  • There is no direct evidence in the provided studies to suggest that MCAS can cause elevated ALT enzymes while AST and ALP remain normal 2, 3, 4, 5, 6.
  • However, it is known that MCAS can affect various organ systems, including the gastrointestinal system, which may indirectly influence liver function and enzyme levels.

Diagnosis and Management of MCAS

  • The diagnosis of MCAS is based on clinical symptoms, increased tryptase levels, and response to antimediator therapy 3, 6.
  • Management of MCAS involves avoiding triggers, modulating mast cell activation, and using medications such as H1/H2 receptor antagonists, anti-leukotrienes, or mast cell stabilizers 2, 5, 6.

Research Gaps and Needs

  • There is a need for further research to understand the underlying mechanisms and pathways that lead to mast cell activation in MCAS patients, as well as the relationship between MCAS and liver enzymes 4.

References

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Research

Clinical Approach to Mast Cell Activation Syndrome: A Practical Overview.

Journal of investigational allergology & clinical immunology, 2021

Research

Mast cell activation syndrome: Current understanding and research needs.

The Journal of allergy and clinical immunology, 2024

Research

Mast Cell Activation Syndrome.

Clinical reviews in allergy & immunology, 2018

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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