Establishment of a normal reference range for alpha 1-antitrypsin in Saudis using rate nephelometry

Alpha 1-antitrypsin level was estimated in 543 healthy males and 603 healthy females using rate nephelometry, in order to establish a "normal reference range" in Saudis. A significantly higher mean and range were encountered in the females than in the males, and a positive correlation was obtained between the alpha 1-antitrypsin level and age. Since alpha 1-antitrypsin showed a positively skewed distribution, the normal reference ranges were established using the 2.5th to 97.5th percentile values. This article presents the normal reference range for alpha 1-antitrypsin as 100 to 250 mg/dl in children under 10 years of age, 95 to 275 mg/dl in adult males and 100 to 350 mg/dl in adult females. The results are discussed in light of the significant differences encountered in comparison with the results reported elsewhere and by the manufacturers of the kits.