The importance of the hypoosmotic swelling test and acrosin activity assay for identifying subpopulations of idiopathic infertile men.

Semen samples collected from fertile donors (n = 13) and pooled samples from idiopathic infertile men (n = 19) were used in this study. Measurements of the total sperm acrosin activity and the hypoosmotic swelling test (HOST) were performed in all the samples. The percentage of swollen spermatozoa and acrosin profiles were significantly lower in the infertile men than in the fertile donors. Considering the lowest values of the outcome of the HOST and the acrosin activity assay in the group of fertile men as the lowest normal values, it was proven that HOST and acrosin activity assay could identify subpopulations of infertile men of 37 and 26%, respectively. The results tend to support the employment of the HOST and the acrosin activity assay in the evaluation of idiopathic infertile men.