I am unaware of either biotin or Keppra (levetiracetam) altering levels of testosterone/estrogen or PSA (Prostate Specific Antigen).
A quick literature search in regard to this yielded no results.
There has been a few studies that suggest anti-epileptic drugs may DECREASE the risk of certain cancers like prostate cancer. There have also been case reports of Keppra causing urinary retention, which may be related to the prostate but any kind of correlation is not definitive.
In regard to biotin, it is well known that many anti-epileptic drugs may DECREASE biotin levels but again, I found no evidence that biotin would affect PSA levels or affect the levels of sex hormones.
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