Relationship between creatine kinase activity and semen characteristics in subfertile men

Creatine kinase is an indicator of sperm maturity. We studied whether sperm creatine kinase levels differ between normal healthy donors and subfertile patients and determined the correlation between sperm creatine kinase level and semen quality in subfertile men.

Semen samples were obtained from 76 subfertile and 15 healthy normal donors after 48 to 72 hours of sexual abstinence. Sperm characteristics were assessed with a computer-assisted semen analyzer. Morphology was evaluated by Kruger's strict criteria and World Health Organization methods. The thiobarbituric acid assay was used to measure lipid peroxidation; sperm creatine kinase activity was measured using a commercial kit after detergent extraction (Triton X-100).

Creatine kinase levels were significantly higher (P < .001) in subfertile men (median = 0.197 U/10(8) sperm) compared with donors (median = 0.061 U/10(8) sperm). In subfertile men, creatine kinase levels correlated significantly with lipid peroxidation levels (r = .49; P = 0.03) and sperm concentration (r = -.70; P < .001), and with normal sperm forms by Kruger's (r = -.30; P = 0.01) and WHO methods (r = -.32; P < .005). Creatine kinase levels and spermatozoal characteristics did not correlate significantly in donors. Compared with subfertile normospermic men, creatine kinase activity was significantly higher in oligospermic and asthenospermic men (P <.001).

The inverse relationship between creatine kinase level and sperm concentration and morphological forms suggests that creatine kinase levels can be a reliable marker for semen quality in subfertile men. An elevated creatine kinase level and its correlation with lipid peroxidation levels may reflect biochemically immature spermatozoa.