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Laboratory Medicine

Test Directory / Alpha-1-Antitrypsin


Brown clotted serum, gel barrier

Common AbbreviationsAAT
Tube typeBrown clotted serum, gel barrier
Clinical IndicationPhysiologically it is most important as an inhibitor of leukocyte elastase, which is released in the process of phagocytosis by polymorphonuclear leukocytes. Increased levels of Alpha-1- antitrypsin are common as it is an acute phase reactant whose plasma concentrations rise several fold in the case of acute or chronic inflammation. Elevated levels are also seen in late pregnancy and during oestrogen therapy because the synthesis of Alpha-1- antitrypsin is stimulated by oestrogens. Low levels of Alpha-1-antitrypsin are found in neonatal respiratory distress syndrome, severe neonatal hepatitis, pre-terminal disease of the pancreas and in severe protein losing enteropathies. A hereditary deficiency of Alpha-1- antitrypsin is associated with pulmonary emphysema and diseases of the liver including neonatal cholestasis (hepatitis), cirrhosis and hepatocellular carcinoma. In Alpha-1- antitrypsin deficiency, levels can fall within the reference interval because of its acute phase function in cases of inflammation. CRP can be measured to distinguish such cases.
Specimen TypeBlood
Sample typeSerum
Minimum Volume0.5mL If requesting more than 10 tests please send an additional brown clotted serum sample.
Special PrecautionsNo special requirements
Stability7 days at 15-25°C; 3 months at 2-8°C
Turnaround TimeInpatient: 4 days Outpatient/ GP: 4 days
Reference IntervalAdults: 1.1 - 2.1 g/L
LimitationsSevere haemolysis, jaundice or lipaemia may interfere with measurement and prevent an AAT value from being reported. Samples with extremely abnormal optical characteristics, especially turbidity may produce atypical results. Samples with very high alpha-1 antitrypsin concentrations (>16 g/L) can generate false low results
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