Abstract
Objective: Detection of the AST macroenzyme in blood serum as a cause of long-Term isolated elevation of the AST enzyme. Design: Original paper Settings: Institute of Clinical and Experimental Medicine, Veňsk1958/9, 140 21 Praha 4 Materials and Methods: Sera of two tested patients were precipitated with polyethylene glycol 6000 (PEG 6000, Sigma Aldrich) in a volume ratio of 1:1.
After centrifugation, AST enzyme activity in the supernatant was determined (Architect ci16200, Abbott). AST enzyme activity values were compared to those of the patient sera, which were diluted with saline (NaCl 9 g/L) in a volume ratio of 1:1.
The results of comparing of the tested patient samples with the two control samples were evaluated as a percentage of PEG-precipitable activity (%PPA). The patient and control sera were stored at 4°C for 144 hours and AST enzyme activity was monitored after each 24 hours.
Results and Conclusions: The presence of macro-AST as the most probable cause of permanently increased activity of AST in serum was confirmed. PEG-precipitable activities in tested patients were 92 and 79 %, respectively.
In contrast, the comparative method of storing samples at 4°C did not reveal any decline of AST activity. These relatively simple and inexpensive laboratory methods of macro-AST detection can save on unnecessary examinations as well as prevent diagnostic errors.