Lysozyme concentration in tears--assessment of reference values in normal subjects.

The lysozyme content of tears in 126 healthy persons (249 samples) was studied by an initial rate immunoturbidimetric method. The lysozyme values kept a logarithmic distribution with logarithmic mean 1568 mg/l and median 1530 mg/l. The arithmetic mean with standard deviation was 1678 +/- 633 mg/l. Lower lysozyme concentrations were observed in elderly people and children than in adults, but the concentration distributions in different age groups overlapped considerably. Statistically, the difference between the age groups less than or equal to 60 years and over 60 years was almost significant (P = 0.012). No significant differences occurred between the sexes. Values within +/- 2 SD from the logarithmic mean were included in the reference material. For 10-60-year-old persons, the reference range is 750-3300 mg/l and over 60 years old 650-2900 mg/l.