By Frederich Kueppers, MD
Alpha-1 antitrypsin deficiency (AATD) is associated with lung and liver disease, and less commonly with necrotizing panniculitis (a skin disorder) and a type of vasculitis.Early diagnosis of AATD is crucial to help slow disease progression—yet, because alpha-1 antitrypsin (AAT) levels fluctuate, accurate diagnosis by conventional quantitative blood tests can be challenging. A new algorithm developed at Temple is now available online to help physicians make a more definitive determination of baseline AAT levels and improve diagnostic speed and accuracy.
AAT is normally present in human blood in the concentration of 83–220 mg/dL. The levels are under genetic control so that most people are homozygous for the common normal gene. Patients who carry variant genes, however, may have low levels of AAT: 40–100 mg/dL, depending on the specific variant and combination with normal alleles.
AAT levels are also influenced by other factors: inflammation, infection or injury may cause an “acute phase reaction” that raises concentrations of AAT temporarily to values 100% or more above the baseline levels, which can obscure an underlying deficiency. Levels of AAT and C-reactive protein (CRP) are closely correlated, because they rise together during an acute phase reaction. At the Temple Lung Center, we have developed an online algorithm that factors in CRP levels to adjust for acute phase responses, thereby allowing us to calculate the baseline AAT level. The tool also takes into consideration the most common deficient genotypes. The algorithm is now available as an easy-to-use online calculator: visit https://predictaat.us ■