Liver and pancreas
Alfa-1 Antitrypsine
A protective protein from the liver; a level that is too low may point to an inherited deficiency with consequences for the lungs and liver.
Everything about this testWhat it measures
Alpha-1 antitrypsin is a protein made by the liver. It mainly protects the lungs against enzymes that white blood cells release during inflammation and that would otherwise break down lung tissue. In an inherited deficiency, the liver makes too little or an abnormal form, which sometimes builds up in the liver. The protein is also an acute-phase protein: with inflammation, infection or pregnancy, it rises temporarily.
- An inherited alpha-1 antitrypsin deficiency, which can cause pulmonary emphysema (COPD) at a young age, especially in smokers
- Liver disease due to buildup of the abnormal form, in children sometimes as long-lasting jaundice
- Carrier status within a family in which the deficiency occurs
High
A raised value is usually due to inflammation or infection, pregnancy, the contraceptive pill or other estrogens, because the body then makes more alpha-1 antitrypsin. A raised value has no meaning on its own and causes no symptoms. It is important, though, that inflammation can mask a deficiency: the value can then seem normal even though there is an inherited deficiency.
Low
A low value fits an inherited deficiency. The lower the value, the greater the risk of lung damage usually is. A slightly low value often fits being a carrier of one abnormal gene; this usually causes no symptoms, but smoking does then increase the risk of lung damage. A strongly low value fits two abnormal genes and can cause shortness of breath, coughing and pulmonary emphysema at a young age, especially in smokers, and sometimes liver disease. A low value can also be caused by protein loss, for example via the kidneys or the gut.
If your result is abnormal
With a low value, the GP usually repeats the test together with CRP and has the inherited variant determined. With a confirmed deficiency, referral follows to a lung specialist, and sometimes a gastroenterologist, for testing of the lungs and liver. Relatives can be tested via the GP or a clinical geneticist. Stopping smoking is extra important with a deficiency.
Reliability
A clearly low value is a reliable sign of an inherited deficiency; which variant someone has only becomes clear from further testing (phenotyping or DNA testing). A normal value does not completely rule out a deficiency, because the value rises during inflammation. The result is most meaningful with COPD or pulmonary emphysema at a young age, with unexplained liver disease and with a known deficiency in the family. The guideline on bronchiectasis considers finding an inherited deficiency important for family testing and for advice when planning to have children.
Limitations
- Inflammation, infection, pregnancy, the contraceptive pill and estrogens raise the value and can mask a deficiency; preferably measure when there is no inflammation, possibly together with CRP.
- Protein loss via the kidneys or gut lowers the value without an inherited deficiency.
- The value alone does not distinguish between carrier status and a severe deficiency; further testing is needed for that.
- Reference values differ per laboratory.
How common is this
A severe inherited alpha-1 antitrypsin deficiency is estimated to occur in about 1 in 5,000 people in the Netherlands. Being a carrier of one abnormal gene is much more common. Many people with a deficiency do not know it, because their symptoms are seen as ordinary COPD or asthma.
Who is this useful for
The result is mainly meaningful with COPD or pulmonary emphysema at a young age or with little or no smoking, with unexplained liver disease or long-lasting jaundice in a child, and in relatives of someone with a known deficiency. In people without symptoms and without such a family history, the chance of a severe deficiency is small. Because it concerns an inherited predisposition, an abnormal result can also say something about brothers, sisters and children.
Downsides and risks
- A slightly low value due to carrier status can cause unnecessary worry, while carriers usually do not develop symptoms.
- The result can have consequences for relatives who did not ask for it themselves.
Sources
Always discuss an abnormal result with your GP. If a result is strongly abnormal, we try to reach you as soon as possible. Read your result yourself as well and contact your GP if in doubt. A test does not make a diagnosis. Read more about risks and results