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Interpretive Handbook

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Test 82514:
Thermoactinomyces vulgaris, IgG Antibodies, Serum

Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

Thermoactinomyces vulgaris is a causative agent of hypersensitivity pneumonitis (HP). Other causative microorganisms include Micropolyspora faeni and Aspergillus fumigatus. While the immunopathogenesis of HP is not known, several immune mechanisms are postulated to play a role, including both cellular and humoral mechanisms.(1)

Useful For Suggests clinical disorders or settings where the test may be helpful

Evaluating patients suspected of having hypersensitivity pneumonitis induced by exposure to this antigen

Interpretation Provides information to assist in interpretation of the test results

Elevated concentrations of IgG antibodies to Thermoactinomyces vulgaris are consistent with the diagnosis of hypersensitivity pneumonitis (HP) caused by exposure to this antigen.

 

Elevated concentrations of IgG antibodies to Thermoactinomyces vulgaris were found in a small number of sera from patients with HP (4%).(2)

Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

IgG antibodies to Thermoactinomyces vulgaris are detectable in healthy individuals, and the presence of antibodies is not sufficient to establish the diagnosis of hypersensitivity pneumonitis (HP) caused by exposure to this antigen.

 

The levels of antibodies decrease following successful treatment of HP; but, elevated levels may persist for long periods.

Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.

0-12 years: < or =6.6 mg/L

13-18 years: < or =11.0 mg/L

>18 years: < or =23.9 mg/L

Clinical References Provides recommendations for further in-depth reading of a clinical nature

1. Fink JN, Zacharisen MC: Hypersensitivity pneumonitis. In Allergy Principles and Practice. Vol. 1. 5th edition. Edited by E Middleton Jr, CE Reed, EF Ellis, et al. St. Louis, MO, Mosby Year Book Inc., 1998, Chapter 19

2. Anderson E, Jacob GL, Roberts GD, Homburger HA: Comparative evaluation of enzyme immunoassay and immunodiffusion for detection of IgG antibodies to hypersensitivity pneumonitis antigens. Poster Presentation AAAAI Annual Meeting, San Diego, CA, March 3-8, 2000. J Allergy Clin Immunol 2000;105:S304