[Alpha 1-antitrypsin in the blood and pleural effusion fluid].

Alpha-1 antitrypsin levels were determined in 27 pleural effusion liquids classified as transudates and exudates in accordance with the clinical and laboratory data, and in their respective blood samples. Absolute values proved insufficient to distinguish transudates from exudates, though they were capable of signifying and replacing the relative protein value. The relation between liquid: serum alpha-1 AT ratio and the liquid: serum proteins ratio was direct and highly significant. Along with the liquid: serum LAD and liquid: serum proteins ratios, the liquid: serum alpha-1 AT ratio enables transudates and exudates to be differentiated with certainty.