Influence of age and sex on five human plasma lysosomal enzymes assayed by automated procedures

Automated fluorimetric procedures for the assay of five lysosomal glycohydrolases—β-N-acetylglucosaminidase; β-galactosidase; β-glucuronidase; α-mannosidase; α-fucosidase—in human plasma were set up. A Carlo Erba autoanalyser CLA 1500, provided with a sampler refrigerating unit and connected with a recording Turner Mod 111 fluorimeter was employed. The automated procedures, under the established optimal conditions, proved to be highly accurate and reproducible.Using the automated assay procedures the effect of sex and age on the plasma levels of the same enzymes was studied. 1273 randomly selected healthy subjects were studied. No sex differences were observed for all the enzymes studied with the exception of β-glucuronidase which displayed higher values (about 30%) in males from 25 to 60 years. The developmental profiles of all enzymes in females and males were similar and characterised by: (a) absolute maximum level in the umbilical cord blood; (b) absolute minimum level at 10–14 years; (c) decrease to a second minimum occurring around 35 years (not displayed by β-galactosidase and by β-glucuronidase in males); (e) slow further increase up to the elderly level which was then maintained till the oldest age examined, 74 years.