Effect of transient scrotal hyperthermia on sperm parameters, seminal plasma biochemical markers, and oxidative stress in men.
Level 3 - non-randomized controlled study
Prospective comparative interventional study without stated randomization in human volunteers.
PubMed 25652627 · doi:10.4103/1008-682X.146967
What was done
Twenty male volunteers were divided into two experimental groups (10 per group) to test the effect of scrotal hyperthermia in a 43°C water bath for 30 minutes per session across 10 sessions total: Group 1 received exposure on 10 consecutive days; Group 2 received exposure once every 3 days. Researchers measured sperm parameters, epididymal and accessory sex gland function, seminal plasma oxidative stress markers (malondialdehyde), and serum sex hormones at baseline and throughout a 16-week recovery period.
What was found
Both groups exhibited statistically significant, reversible reductions from baseline in minimum sperm concentration (P = 0.005 for Group 1; P = 0.008 for Group 2), motility (P = 0.009; P = 0.021), hypoosmotic swelling test score (P = 0.007; P = 0.008), and total acrosin activity (P = 0.018; P = 0.009). Seminal plasma malondialdehyde significantly increased in both groups (P = 0.005; P = 0.017). The reduction in sperm concentration was significantly greater in Group 2 (intermittent exposure) than in Group 1 (consecutive exposure; P = 0.031). Specific absolute numbers and baseline values were not reported in the abstract.
Why it matters
This study demonstrates that transient scrotal hyperthermia causes reversible suppression of human spermatogenesis with concurrent increases in seminal oxidative stress, with intermittent heat exposure resulting in greater suppression than consecutive daily exposure.
Limits
The total sample size was small (20 participants, 10 per group). The abstract does not report randomization to the two exposure schedules. Absolute baseline values, post-treatment numbers, effect sizes, confidence intervals, and hormone outcomes are omitted from the abstract.
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