RESUMO
N-acetyl-beta-glucosaminidase (NAG) is a lysosomal enzyme found in most human cells, including those from the nervous system and kidneys. There are several different NAG forms in human tissues and fluids, but isoenzymes A and B are the most abundant, presenting about 98% of the whole NAG activity in normal serum. The paper is dealing with the total NAG serum level, main isoenzymes (A and B) activity, their ratio and possible lithium ion influence in affectively disordered patients. The sample consisted of thirteen bipolar-euthymic patients who had been receiving lithium for more than two years. The results pointed out reduction in total serum NAG activity, the lithium ion influence absence on total serum NAG activity, but at the same time the important modifying effects on isoenzyme NAG activities.