Reference and Interpretive Ranges for alpha(1)-Antitrypsin Quantitation by Phenotype in Adult and Pediatric Populations

Division of Clinical Biochemistry and Immunology, Department of Laboratory Medicine and Pathology, Mayo Clinic, 200 First St SW, Rochester, MN 55905, USA.
American Journal of Clinical Pathology (Impact Factor: 3.01). 09/2012; 138(3):398-405. DOI: 10.1309/AJCPMEEJK32ACYFP
Source: PubMed

ABSTRACT Laboratory evaluation of α(1)-antitrypsin (A1AT) deficiency involves measurement of circulating A1AT protein (quantitation) and characterization of A1AT genetic polymorphisms (phenotyping or genotyping). This study compared adult and pediatric A1AT reference ranges in patients with nondeficiency alleles and examined A1AT concentrations in multiple other phenotypes. A1AT phenotype and quantitation were retrospectively collected on adult (n = 21,444) and pediatric (n = 2,469) samples that were submitted for laboratory evaluation of A1AT deficiency. The 95% reference ranges for normal adult and pediatric populations with the M/M phenotype were determined to be 100 to 273 mg/dL (18.4-50.2 μmol/L) and 93 to 251 mg/dL (17.1-46.2 μmol/L), respectively (P < .0001). Decreased concentrations of A1AT correlated with heterozygosity and homozygosity for the S and Z alleles in both the adult and pediatric groups. Other rare alleles, such as I, were also associated with decreased concentrations of A1AT, particularly in the context of a Z allele, and may warrant monitoring for symptoms of deficiency.

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