Clinical Background
Anaphylaxis is an acute, potentially fatal allergic reaction involving the respiratory, skin, circulatory, and immune systems.
Epidemiology
- Prevalence - 75/100,000 lifetime incidence
- Age - spans all age groups
- Sex - M:F; equal
Risk Factors
- Previous history of anaphylaxis; hives or urticaria following allergen exposure
Pathophysiology
- Involves activated mast cell release of multiple substances - cytokines, histamine, tryptase, prostaglandins
- Some forms are IgE mediated; others are not
- IgE mediated
- Medications
- Foods
- Insect venoms
- IgE independent
- Cold, heat
- Drugs - opioids, muscle relaxants, NSAIDS, ACE inhibitors
- Exercise
- Radiocontrast media
- Interval to anaphylaxis depends on allergen
- Food - 25-30 minutes after ingestion
- Drugs - 10-20 minutes after administration
- Insect stings - 10-15 minutes after sting
- Blood or blood products in IgA deficient patients (no detectable level)
Clinical Presentation
- Respiratory - dyspnea, tachypnea, bronchospasm, laryngeal or tongue edema
- Cardiovascular - tachycardia, hypotension, cardiac arrhythmias, angina, cardiac arrest
- Gastrointestinal - nausea, abdominal cramps, emesis, diarrhea
- Cutaneous - erythema, generalized pruritus, urticaria, angioedema
- Other - rhinitis, cramps, dizziness, syncope
Treatment
- Immediate
- Epinephrine
- Antihistamines
- Corticosteroids
- Observation after initial treatment, fluid administration
Prevention
- Avoidance of known allergens
- Use of epinephrine pens when exposed to known allergen; epinephrine should be available at all times for possible repeat exposures
- Desensitization for insect stings
See Also
Diagnosis
Diagnosis
- Clinical history and examination consistent with anaphylaxis
- Laboratory testing
- Serum tryptase
- Levels peak 1 hour after onset of anaphylaxis
- Elevation persists for 4-6 hours
- Serum or plasma histamine
- Levels peak 5 minutes after onset of anaphylaxis
- Return to baseline levels within 30-60 minutes
- May be elevated in serum due to artifactual basophil activation during clotting
- Urine histamine
- Levels of a histamine metabolite, N-methylhistamine, remain elevated in the urine for many hours after anaphylaxis
- Reflects overall levels of released histamine
- Appropriate IgE testing
- Single IgE level may be helpful
- Multiple allergen IgE testing based on suspicion of allergen
- No recommendations for broad IgE testing
- Caution - in vitro IgE detection may not correlate with anaphylaxis potential of an allergen
Differential Diagnosis
- Vasovagal reaction
- Panic attack
- Flush syndrome
- Hereditary or acquired angioedema
- Other forms of shock
- Systemic mastocytosis
Tests generally appear in the order most useful for common clinical situations
| Test name: Tryptase
|
| ARUP #: 0099173 |
| Methodology: Fluorescence Immunoassay
|
| Use: May be useful in confirming anaphylaxis |
| Limitations: This assay measures total tryptase; it does not distinguish between alpha and beta protein types |
| Test name: Immunoglobulin E
|
| ARUP #: 0050345 |
| Methodology: Electrochemiluminescent Immunoassay
|
| Use: Useful test for confirming IgE-mediated reactions such as anaphylaxis but may be negative to the causative allergen in some cases |
Additional Tests Available
| Test name: Histamine, Whole Blood
|
| ARUP #: 0070037 |
| Methodology: Enzyme Immunoassay
|
| Comments: |
| Test name: Histamine, Plasma
|
| ARUP #: 0070036 |
| Methodology: Enzyme Immunoassay
|
| Comments: |
| Test name: Histamine, Urine
|
| ARUP #: 0070038 |
| Methodology: Enzyme Immunoassay
|
| Comments: |
References
Guidelines
The diagnosis and management of anaphylaxis: an updated practice parameter. American Academy of Allergy, Asthma and Immunology - Medical Specialty Society
American College of Allergy, Asthma and Immunology - Medical Specialty Society
Joint Council of Allergy, Asthma and Immunology - Medical Specialty Society. 1998 Jun (revised 2005 Mar). 41 pages. NGC:004211 General References
Kemp SF, Lockey RF. Anaphylaxis: a review of causes and mechanisms. J Allergy Clin Immunol.
2002;
110(
3):
341-348.
Kemp SF. Office approach to anaphylaxis: sooner better than later. Am J Med.
2007;
120(
8):
664-668.
Lieberman P, Camargo CA Jr, Bohlke K, Jick H, Miller RL, Sheikh A, Simons FE. Epidemiology of anaphylaxis: findings of the American College of Allergy, Asthma and Immunology Epidemiology of Anaphylaxis Working Group. Ann Allergy Asthma Immunol.
2006;
97(
5):
596-602.
Sampson HA, Munoz-Furlong A, Campbell RL, Adkinson NF Jr, Bock SA, Branum A, Brown SG, Camargo CA Jr, Cydulka R, Galli SJ, Gidudu J, Gruchalla RS, Harlor AD Jr, Hepner DL, Lewis LM, Lieberman PL, Metcalfe DD, O'Connor R, Muraro A, Rudman A, Schmitt C, Scherrer D, Simons FE, Thomas S, Wood JP, Decker WW. Second symposium on the definition and management of anaphylaxis: summary report--second National Institute of Allergy and Infectious Disease/Food Allergy and Anaphylaxis Network symposium. Ann Emerg Med.
2006;
47(
4):
373-380.
Sampson HA, Munoz-Furlong A, Campbell RL, Adkinson NF Jr, Bock SA, Branum A, Brown SG, Camargo CA Jr, Cydulka R, Galli SJ, Gidudu J, Gruchalla RS, Harlor AD Jr, Hepner DL, Lewis LM, Lieberman PL, Metcalfe DD, O'Connor R, Muraro A, Rudman A, Schmitt C, Scherrer D, Simons FE, Thomas S, Wood JP, Decker WW. Second symposium on the definition and management of anaphylaxis: summary report--Second National Institute of Allergy and Infectious Disease/Food Allergy and Anaphylaxis Network symposium. J Allergy Clin Immunol.
2006;
117(
2):
391-397.
Medical Reviewers
Grenache, David G., Ph.D. Medical Director, Special Chemistry at ARUP Laboratories; Assistant Professor, Clinical Pathology, University of Utah
Hill, Harry R., M.D. Group Medical Director, Laboratory of Immunology, ARUP Laboratories, and Executive Director of the ARUP Institute for Clinical and Experimental Pathology; Professor and Division Head, Clinical Pathology, University of Utah
Roberts, William L. , M.D., Ph.D. Medical Director, Automated Core Laboratory at ARUP Laboratories; Professor, Pathology, University of Utah
Tebo, Anne E., Ph.D. Assistant Medical Director, Immunology at ARUP Laboratories; Clinical Assistant Professor, Clinical Pathology, University of Utah
Comprehensive Review: March 2008
Last Update: July 2008
