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Validation and development of an immunonephelometric assay for the determination of alpha-1 antitrypsin levels in dried blood spots from patients with COPD

Authors :
Laura Russo Zillmer
Rodrigo Russo
Beatriz Martins Manzano
Ivan Ivanaga
Oliver Augusto Nascimento
Altay Alves Lino de Souza
Gildo Santos Junior
Francisco Rodriguez
Marc Miravitlles
Jose Roberto Jardim
Source :
Jornal Brasileiro de Pneumologia, Vol 39, Iss 5, Pp 547-554 (2013)
Publication Year :
2013
Publisher :
Sociedade Brasileira de Pneumologia e Tisiologia, 2013.

Abstract

OBJECTIVE: To validate and develop an immunonephelometric assay for the determination of alpha-1 antitrypsin (AAT) levels in dried blood spots from COPD patients in Brazil. METHODS: We determined AAT levels in serum samples and dried blood spots from 192 COPD patients. For the preparation of dried blood spots, a disk (diameter, 6 mm) was placed into a tube, eluted with 200 µL of PBS, and stored overnight at 4ºC. All of the samples were analyzed by immunonephelometry in duplicate. We used the bootstrap resampling method in order to determine a cut-off point for AAT levels in dried blood spots. RESULTS: The correlation coefficient between the AAT levels in serum samples and those in dried blood spots was r = 0.45. For dried blood spots, the cut-off value was 2.02 mg/dL (97% CI: 1.45-2.64 mg/dL), with a sensitivity, specificity, positive predictive value, and negative predictive value of 100%, 95.7%, 27.2%, and 100%, respectively. CONCLUSIONS: This method for the determination of AAT levels in dried blood spots appears to be a reliable screening tool for patients with AAT deficiency.

Details

Language :
English, Portuguese
ISSN :
18063756 and 18063713
Volume :
39
Issue :
5
Database :
Directory of Open Access Journals
Journal :
Jornal Brasileiro de Pneumologia
Publication Type :
Academic Journal
Accession number :
edsdoj.454679f1ace2431d9a348c23533b1f9d
Document Type :
article
Full Text :
https://doi.org/10.1590/S1806-37132013000500004