tokens: Most of the other low testosterone levels seemed to result from nonorganic hypothalamic dysfunction because of normal serum luteinizing hormone and prolactin and to have only a small role in erectile dysfunction ( definite improvement in only 16 of 44 [ 36 %] after androgen therapy , normal morning or nocturnal erections in 30 % and definite vasculogenic contributions in 42 %). Determining testosterone only in cases of low sexual desire or abnormal physical examination would have missed 40 % of the cases with low testosterone , including 37 % of those subsequently improved by androgen therapy .