An alpha 1 antitrypsin test is worth discussing if you have COPD, unexplained liver disease, or a close relative with alpha-1 antitrypsin deficiency (AATD). Testing can identify an inherited risk that may affect lung care, liver monitoring, and decisions about testing relatives. A low blood level is a clue, not always a complete diagnosis: results usually need to be interpreted alongside genetic or protein-variant testing.
WHO Should Have an alpha 1 antitrypsin test?
Major respiratory guidance recommends testing people with COPD or persistent airflow obstruction, including when it has been labelled as asthma. Testing is especially relevant with early-onset disease, emphysema, or little or no smoking history, but you do not need to fit that pattern for testing to be considered.
Clinicians also consider testing for unexplained bronchiectasis or chronic liver disease, and for certain rare conditions such as panniculitis or granulomatosis with polyangiitis. A family history of AATD is another reason to ask about testing. AATD can resemble more common lung or liver conditions, so symptoms alone cannot confirm or exclude it.
How Blood And Genetic Tests Fit Together
The first step is often a blood test measuring alpha-1 antitrypsin (AAT), a protein made mainly in the liver that helps protect lung tissue. The result may be reported in mg/dL or g/L; for example, 57 mg/dL is 0.57 g/L. Reference ranges and follow-up thresholds vary by laboratory and testing method, so a result should be read against the lab’s range and clinical context rather than a single universal “normal” number.
Many pathways use a low AAT result to prompt further testing. A level at or below about 100 mg/dL (1.0 g/L) may warrant confirmation, while severe deficiency is conventionally associated with levels below about 57 mg/dL (0.57 g/L, or 11 μM). These are useful guideposts, not interchangeable cutoffs: a level near a threshold does not, by itself, establish which gene variants you have or what your individual disease risk is.
AAT is an acute-phase protein, meaning its blood level can rise during infection or inflammation. That can make a deficient level look less low than expected. A clinician may check an inflammation marker such as C-reactive protein (CRP) or repeat the AAT measurement when you are well.
Confirmation commonly involves testing for gene variants (genotyping), identifying the AAT protein type (phenotyping), or both. Common results include PiZZ, usually associated with severe deficiency; PiSZ, often associated with an intermediate level; and PiMZ, which generally indicates one Z variant. A targeted test may look for common S and Z variants. If the blood level and initial genetic result do not match, or a rare variant is suspected, further specialist testing may be needed. More than 200 SERPINA1 variants have been described, and the significance of some rare variants is not fully understood.
What A Diagnosis Can Change
For lung care, knowing the cause of COPD can support appropriate monitoring and reinforce steps to limit lung injury, including avoiding smoking. It does not replace usual COPD care. People with AATD-related emphysema are generally managed using standard approaches for emphysema and COPD, with care tailored to their condition.
AATD can also affect the liver, particularly with variants that cause abnormal AAT protein to build up in liver cells. A confirmed diagnosis can prompt clinicians to assess liver health and decide whether follow-up is appropriate. The monitoring plan depends on your results and health; there is no one schedule in the guidance described here that fits everyone. Normal liver blood tests also do not always answer every question about liver health, as explained in this guide to why normal liver tests may not settle follow-up decisions.
Intravenous augmentation therapy, made from pooled human plasma-derived AAT, is a disease-modifying treatment used for selected people with AATD-related lung disease. It is not a treatment for liver disease, and a low blood level alone does not establish eligibility. Availability and reimbursement vary across countries and health systems, so diagnosis does not guarantee access.
Why Relatives May Be Offered Testing
AATD is inherited, so a confirmed result can help close relatives understand whether they may carry relevant variants. Guidance commonly supports offering testing to first-degree relatives; approaches to family testing differ among countries. In the UK, for example, a local NHS laboratory fact sheet notes that there are no UK guidelines for family studies, while describing European guidance that recommends offering testing to siblings and partners. Ask the clinician who arranged your test what pathway applies locally. Genetic counselling can help you consider what a result could mean for relatives and family planning.
If you have COPD, unexplained liver disease, or a close relative diagnosed with AATD, ask your clinician whether testing is appropriate. Seek their help interpreting results, especially if the blood level and genetic findings do not agree.
