To the Editor The study by Grashow et al1 on the association of a history of concussion symptoms with self-reported low testosterone levels and erectile dysfunction (ED) seems to suggest that concussion leads to persistent pituitary damage. The body of research regarding traumatic brain injury (TBI) and pituitary dysfunction, including evidence cited by Grashow et al, supports an association between moderate to severe TBI and hypopituitarism, but to our knowledge, research specifically examining the association between concussion and hypopituitarism is lacking. Although pituitary dysfunction is not uncommon following moderate to severe TBI, hypogonadism is often transient,2 and there is little empirical evidence to support the claim that mild TBI is associated with hypogonadism in the short or long term.