Serum lysozyme (muramidase) levels in healthy subjects aged 10-90 years

Lysozyme (LYS) levels were tested in the serum of 1,399 subjects (670 males, 729 females). A curve was plotted from the mean values. In our series, both sexes attained their highest peak at about 10 years. Between 21 and 30 years the curves of the two sexes began to diverge and in the 31- to 40-year decade the male curve attained a second maximum. This inter-sex difference was highly significant (P less than 0.01). Between 41 and 50 years the LYS values of the two sexes began to come closer again and from the 51- to 60-year decade they ran parallel with each other without deviating. The significance of the two courses is discussed.