Alternative name: AAT
General information α1-Antitrypsin deficiency
Description: α1-antitrypsin is an enzyme inhibitor which inactivates the proteases released by inflammatory cells particularly neutrophils. Measurement of α1-antitrypsin by nephelometry is useful in the investigation of emphysema and unexplained liver disease in adults and neonatal jaundice, all of which can be associated with geneticaly determined low levels of α1-antitrypsin. Patients with low a1-antitrypsin will be phenotyped to detect homozygous or heterozygous deficiency state. There are many phenotypes. Some rarer phenotypes give normal serum levels of an inactive α1-antitrypsin. Genotyping might be required in patients with severe deficiencies and their relatives. Smoking markedly exacerbates the effects of α1 antitrypsin deficiency.Low levels of α1-antitrypsin may be detected during electrophoresis used fpr monitoring of immunoglobulin levels. The laboratory will automatically measure α1-antitrypsin levels in such samples.
Indication: Detection of α1-antitrypsin deficiency associated with chronic obstructive airways disease, emphysema or neonatal/juvenile liver disease.
Interpretation: A low level of α1-antitrypsin may be the cause of these diseases or may indicate the likelhood of them developing later in life. In all sera with a1-antitrypsin below the normal range the α1-antitrypsin phenotypewill be determined to identify pateints at risk.Note that α1-antitrypsin is an acute phase protein and therefore in inflammatory conditions levels may rise, masking genetic deficiency. Increased levels also occur in malignancy, pregnancy and during oestrogen therapy.
Sample: Serum Separator Tube (SST)
Assay details: Nephelometry
Restrictions: Lipaemia
Reference range: 1.1 – 2.1g/L (adult)
Assay range notes: Levels are age related. With lower end of range increasing in children up to around 9 years of age. 1.0 g/L used as a lower limit of normal for identification of samples for phenotypic deficiency analysis.
Turnaround time: 5 – 7 Days
Analysing laboratory: Immunology