Determination of
sperm DNA fragmentation, as assessed by the
sperm chromatin structure assay (SCSA), has become an important tool for the evaluation of
semen quality. The aim of the present study was to describe the biological variation of
sperm DNA fragmentation in men attending an
andrology clinic and to identify clinical
correlates of the biological variation of
sperm DNA fragmentation. For this study, two consecutive
semen samples from 100 patients attending our
andrology outpatient clinic were subjected to
semen analysis, performed in parallel according to WHO guidelines and by SCSA. A good agreement between pairs of samples was found for SCSA-derived variables, as indicated by a significantly lower
median coefficient of variation (CV) of the
DNA Fragmentation Index (DFI) and the high
DNA stainability (HDS) compared with WHO
semen parameters. In half of the men attending our
andrology clinic, however, the individual biological variation of DFI and HDS, expressed as CV of two samples, exceeded 10%.
Dysregulation of
spermatogenesis, as seen as
testicular insufficiency or
varicocele, was not associated with increased variability of DFI or HDS. A backward
multiple linear regression analysis, however, indicated that the biological variation of DFI may be more profound in men with characteristics of normal
spermatogenesis. In conclusion, we confirm previous reports that
sperm DNA fragmentation has a lower biological variability than classical
semen parameters. We hypothesize that the
sperm chromatin structure may be more influenced in patients with normal
spermatogenesis, whereas in men with disturbed
spermatogenesis, the
chromatin structure may be already so
impaired that the effect of unidentified factors leading to variability of
sperm DNA fragmentation in time may not be as profound.
