A 47-year old man who was recently married for the third time was evaluated for erectile dysfunction which had been marked over the past few years and failed to respond to oral phosphodiesterase-5 inhibitors (PDE5i). He failed to impregnate his previous two wives. On examination, the tall (190 cm) patient’s testicles were found to be small and firm (4 ml measured by orchidometer). Bilateral gynaecomastia was evident. He had fructose positive azoospermia though the seminal fructose was found to be low (8.1 µmol/ejaculate). Gonadotropins were markedly elevated. Total and free testosterone were very low. Karyotype testing showed 47, XXY. Diagnosis of Klinefelter’s syndrome was made. Testosterone replacement therapy did not significantly improve his erectile dysfunction which was successfully treated with combined testosterone replacement therapy and oral sildenafil. It should be noted that a threshold serum testosterone level is required to achieve full efficacy with PDE5i.
Klinefelter’s syndrome was named after Harry Klinefelter, an endocrinologist at Massachusetts General Hospital, in 1942 who thought it was an endocrine disorder due to lack of a second testicular hormone that he postulated but was unable to identify. The postulated hormone, inhibin, was isolated later. The 47, XXY karyotype characteristic of Klinefelter syndrome was first described in Scotland in 1959.