Alpha-1 testing
Learn about the testing options for alpha-1 antitrypsin deficiency, how serum levels are measured, and the importance of confirmatory testing.
Alpha-1 antitrypsin deficiency (A1AD) can be detected by a simple blood test that indicates the serum level of Alpha-1 antitrypsin (AAT). If the serum blood level is low (usually less than 50% of normal), your physician may order other tests to determine phenotype and/or genotype. Some provincial laboratories automatically have further testing done if the blood concentration is below 50% of normal.
There are two different methods of expressing the blood test results for alpha-1, which can lead to confusion among patients. Many commercially available standards have an abnormally high normal range (1.5 – 3.0 g/L). Expression as a percent of normal is valid, as this is not dependent upon units and can apply to any normal range. The following is a rough approximation of the ranges/levels and how the two systems of interpretation correlate with each other. To convert from the milligrams per decilitre scale to the grams per litre scale, divide by 100.
| Phenotype | % of Normal | mg/dL | g/L |
| MM | 80 – 120 | 106 – 158 | 1.06 – 1.58 |
| MZ | 50 - 85 | 66 – 112 | .66 – 1.12 |
| MS | 65 – 90 | 86 – 119 | .86 – 1.19 |
| SZ | 31 – 91 | 41 – 120 | .41 – 1.2 |
| ZZ | 14 – 24 | 18 – 32 | .18 – .32 |
| Null-Null | not detectable | 0 | 0 |
Commercial laboratory standards may be inappropriately high (e.g. 1.5-3 g/L)
mM = micromolar
mg/dL = milligrams per decilitre
g/L = grams per litre
Alpha-1 cannot be diagnosed by symptoms or by a medical examination alone; you need to get a simple, reliable blood test to know for sure.
Testing serum levels of Alpha-1 antitrypsin (AAT) is available throughout Canada. Alpha-1 testing begins with a routine serum test. In cases where a low serum level is detected, additional confirmatory testing is required to identify and characterize the presence and severity of the genetic deficiency. Confirmatory testing is widely available to all Canadian physicians. Due to regional differences in the requisition process, the information will be specific to each province or territory. If a patient or physician would like more information about accessing alpha-1 genetic testing in their region, don’t hesitate to contact AlphaNet Canada at info@alphanetcanada.ca.
