Anaphylaxis Diagnosis and Treatment

Introduction to Histamine Release and Mast Cell Disorders

• Medications such as certain antibiotics, pain relievers, and muscle relaxants can trigger histamine release from mast cells, according to the American Academy of Allergy, Asthma, and Immunology 1
• Increased mast cell burden in mast cell disorders leads to higher histamine production, characterized by elevated baseline tryptase levels, as recommended by the American Academy of Allergy, Asthma, and Immunology 1

Diagnostic Biomarkers

• Plasma histamine levels increase within 5-10 minutes of symptom onset and remain elevated for 30-60 minutes, while urinary histamine metabolites are elevated for up to 24 hours, and serum tryptase peaks 60-90 minutes after onset and persists for up to 6 hours, as stated by the American Academy of Allergy, Asthma, and Immunology 1
• The following table summarizes diagnostic approaches:

• Measurement of urinary histamine metabolites, such as 24-hour urinary N-methylhistamine, can be helpful in diagnosis, according to the European Academy of Allergy and Clinical Immunology 2
• A comprehensive diagnostic approach is essential, including ruling out other conditions with similar presentations, and considering histamine intolerance when symptoms occur after consuming histamine-containing foods, multiple organ systems are affected, and DAO activity is reduced 3, 4, 5, 2, 6

Symptoms and Treatment

• Symptoms of histamine intolerance include headaches, flushing, digestive issues, cardiovascular symptoms, and respiratory symptoms in severe cases, and can be similar to those of IgE-mediated allergies and mast cell disorders 4, 5, 2, 6
• The treatment approach should include a step-wise approach, starting with second-generation H1 antihistamines, and adding H2 receptor antagonists, leukotriene modifiers, or oral cromolyn sodium as needed, with consideration of short-term systemic corticosteroids for severe, refractory cases 2, 7
• Second-generation H1 antihistamines (such as generic substitutes for cetirizine, fexofenadine, loratadine) are preferred due to less sedation, as recommended by allergy guideline societies, and combined H1 and H2 antihistamine therapy is recommended for controlling histamine-related symptoms 2
• DAO supplements target dietary histamine in the gut, but do not prevent mast cell degranulation or histamine release from cells, and cannot prevent histamine release triggered by allergens or other stimuli 2

Dietary Management

• A low-histamine diet, which avoids fermented foods, aged cheeses, processed meats, and other high-histamine foods, is a recommended approach for managing histamine-related symptoms, as suggested by nutrition guideline societies 2
• Fresh vegetables, including radicchio, are generally considered safe for consumption by individuals with histamine intolerance, as they are non-fermented, typically consumed fresh, and not processed in ways that increase histamine content 3
• Individual tolerance varies significantly among those with histamine intolerance, making personalized dietary recommendations crucial, and a 4-week elimination diet followed by systematic reintroduction is recommended to identify personal triggers 8
• Foods with higher histamine levels include fermented foods, aged cheeses, processed meats, alcoholic beverages, and certain fruits and vegetables, which should be avoided in low-histamine diets 3, 4, 5

Special Considerations

• Elderly patients should avoid first-generation antihistamines due to increased risk of falls, cognitive impairment, and anticholinergic effects, as recommended by 9, 2, 10, 11, 12
• Patients at risk of anaphylactic reactions should carry two epinephrine autoinjectors, as recommended by 9, 2, 10, 11, 12, and intramuscular injection of epinephrine in the anterior-lateral thigh is recommended for anaphylaxis treatment, with doses of 0.15 mg for patients 10-25 kg and 0.3 mg for patients over 25 kg, as recommended by the American Academy of Allergy and Clinical Immunology 13, 14
• Elevated histamine levels can disrupt the hypothalamic-pituitary axis, potentially affecting sex hormone production, particularly in patients with liver disease, according to the American Association for the Study of Liver Diseases 15
• Cancer survivors frequently experience sexual dysfunction due to multiple factors, including treatment effects on hormonal systems that may involve histamine pathways, as noted by the National Comprehensive Cancer Network 16 and the American Society of Clinical Oncology 17