Biochemical Alteration in Serum Alpha-1 Antitrypsin Levels in Patients with Chronic Obstructive Pulmonary Disease

COPD has been projected as the fourth leading cause of death globally by 2030. WHO recommends screening of COPD subjects for Alpha-1 Antitrypsin (A1AT) deficiency. Serum A1AT below 20% of normal value indicates A1AT deficiency. However, studies regarding its normal levels are seldom and its actual alteration in COPD is lacking. This study was planned to understand biochemical alteration in A1AT levels in COPD, explore impact of COPD and smoking on A1AT, its diagnostic utility, and determine the reference interval. Study was composed of 96 stable subjects with COPD (Group I) and 96 subjects with normal lung function (Group II). Each group contained an equal number of smokers and nonsmokers. Receiver Operating Characteristic curve was generated to determine the cut off value. Mean +/- SD of serum A1AT in Group I and II was 193.82 +/- 54.11, and 157.07 +/- 55.01 mg/dL respectively; in smokers and nonsmokers of Group I was 200.17 +/- 56.29 and 187.48 +/- 51.65 mg/dL respectively while in Group II, was 166.25 +/- 57.79 and 147.88 +/- 51.03 mg/dL respectively. Reference interval of serum A1AT in study population was 157 +/- 55 mg/dL. In total contradiction to its deficiency in COPD, increased levels were found. ANOVA also suggested significant impact of COPD on A1AT and indicated, COPD itself being responsible for increased A1AT and smoking does not interfering. However, based on sensitivity, specificity and area under the curve, A1AT does not appear to have the desired clinical utility towards diagnosis of COPD.