<prompt> For the following causes of sexual dysfunction, select the most likely clinical feature.Can be caused by high prolactin level.loss of sexual desirefailure of erection with absent nocturnal penile tumescence NPTabsence of emissionabsence of orgasm with normal libido and erectile function  <response>: High prolactin level suppresses luteinizing hormone-releasing hormone LH-RH, and can result in low plasma gonadotropin and testosterone levels. It may not be obvious on physical examination. Therapy with a dopamine agonist may lower prolactin levels and reverse impotence. 