Alpha-1 Antitrypsin

Description

The Alpha-1 Antitrypsin (AAT) Test from BiomarkersLabs.com measures the serum concentration of alpha-1 antitrypsin — a serine protease inhibitor synthesised primarily by the liver that protects tissues, particularly lung parenchyma and liver cells, from destructive neutrophil-derived proteases including neutrophil elastase. Alpha-1 Antitrypsin Deficiency (AATD) is a common but severely underdiagnosed autosomal codominant genetic disorder caused by mutations in the SERPINA1 gene — the most common pathogenic variant being the Z allele (Glu342Lys), which produces misfolded AAT protein that polymerises and accumulates in hepatocytes rather than being secreted, causing both deficiency of circulating AAT (leading to unopposed neutrophil elastase-driven lung destruction) and hepatocellular toxicity from the accumulated misfolded protein. AATD is the most common genetic cause of liver disease in children and adults and the most common genetic cause of early-onset emphysema, affecting approximately 1 in 3,500 individuals of Northern European descent. Despite this prevalence, the average time from symptom onset to diagnosis is 5–7 years due to systematic underdiagnosis. Specimens processed through CLIA-certified partner laboratories. Results delivered within 2–4 business days. Available in USA · EU · UK · Canada. Licensed practitioners only.

What does this test measure?

Alpha-1 Antitrypsin (Serum) — Quantitative serum AAT concentration measured by immunonephelometry or ELISA, reported in mg/dL or g/L. Normal range approximately 100–200 mg/dL (1.0–2.0 g/L). Values below 80 mg/dL suggest moderate to severe deficiency; values below 50 mg/dL indicate severe deficiency consistent with ZZ homozygosity. Reduced AAT confirms deficiency; phenotyping or genotyping is required for definitive allele identification. AAT is also an acute phase reactant — it rises during inflammation, meaning that a normal AAT result in an acutely unwell patient may not exclude deficiency; retesting at clinical baseline is required if AAT deficiency is suspected in a patient with concurrent inflammation.

Clinical indications

Suspected Alpha-1 Antitrypsin deficiency — any patient with the clinical features described below should have AAT measured as a first-line investigation.

Unexplained chronic liver disease in adults — AAT is mandatory in any adult with unexplained chronic liver disease, elevated transaminases of unknown aetiology, or liver cirrhosis without identified cause.

Early-onset emphysema or COPD without significant smoking history — emphysema developing before age 45, emphysema with predominantly basilar distribution, or COPD in a never- or minimal-smoker are classic presentations of AATD requiring AAT measurement.

Family history of AAT deficiency — first-degree relatives of confirmed AATD patients should be tested; the codominant inheritance means siblings have a 25% chance of sharing the ZZ genotype.

Chronic obstructive pulmonary disease with atypical presentation — COPD at a young age, rapid progression despite smoking cessation, or unusually severe disease for the smoking history warrants AAT testing.

Neonatal or childhood liver disease — AATD is the most common genetic cause of neonatal hepatitis and cholestasis; AAT measurement is part of neonatal/paediatric liver disease investigation.

Sample type and collection

Blood (serum). No fasting required. 2–4 business days. USA · EU · UK · Canada. No New York restriction. CLIA · IVDR · CE · HIPAA · GDPR · PIPEDA. Register free at BiomarkersLabs.com. Licensed practitioners only. Pay per test.