The Massachusetts Male Aging Study (MMAS) documented an inverse correlation between ED risk and high-density lipoprotein (HDL) cholesterol levels but did not identify any effect from elevated total cholesterol levels.  Another study involving male subjects aged 45-54 years found a correlation with abnormal HDL cholesterol levels but also found a correlation with elevated total cholesterol levels. The MMAS included a preponderance of older men.
Impotence, also called erectile dysfunction, in general, the inability of a man to achieve or maintain penile erection and hence the inability to participate fully in sexual intercourse. In its broadest sense the term impotence refers to the inability to become sexually aroused; in this sense it can apply to women as well as to men. In common practice, however, the term has traditionally been used to describe only male sexual dysfunctions. Professional sex therapists, while they identify two distinct dysfunctions as forms of impotence, prefer not to use the term impotence per se. Thus, because of its pejorative connotation in lay usage and because of confusion about its definition, the word impotence has been eliminated from the technical vocabulary in favour of the term “erectile dysfunction.”
It can also help to tell your partner (either before you start or when it happens) that hey, sometimes it takes your penis a while to warm up or sometimes it comes and goes as it pleases — and that they shouldn't take it personally and you won't let it ruin the moment. When it happens, take a few deep breaths, focus on your partner, and go back to doing whatever was feeling good before. "If they approach that with authentic confidence, the partner is usually like 'OK, cool,'" says Skyler. "Remember, you're more than just your penis."
The appropriate evaluation of all men with erectile dysfunction should include a medical and detailed sexual history (including practices and techniques), a physical examination, a psycho-social evaluation, and basic laboratory studies. When available, a multidisciplinary approach to this evaluation may be desirable. In selected patients, further physiologic or invasive studies may be indicated. A sensitive sexual history, including expectations and motivations, should be obtained from the patient (and sexual partner whenever possible) in an interview conducted by an interested physician or another specially trained professional. A written patient questionnaire may be helpful but is not a substitute for the interview. The sexual history is needed to accurately define the patient's specific complaint and to distinguish between true erectile dysfunction, changes in sexual desire, and orgasmic or ejaculatory disturbances. The patient should be asked specifically about perceptions of his erectile dysfunction, including the nature of onset, frequency, quality, and duration of erections; the presence of nocturnal or morning erections; and his ability to achieve sexual satisfaction. Psychosocial factors related to erectile dysfunction should be probed, including specific situational circumstances, performance anxiety, the nature of sexual relationships, details of current sexual techniques, expectations, motivation for treatment, and the presence of specific discord in the patient's relationship with his sexual partner. The sexual partner's own expectations and perceptions should also be sought since they may have important bearing on diagnosis and treatment recommendations.
Qaseem, A., Snow, V., Denberg, T. D., Casey, D. E., Forciea, M. A., Owens, D. K., & Shekelle, P. (2009). Hormonal testing and pharmacologic treatment of erectile dysfunction: A clinical practice guideline from the American College of Physicians. Annals of internal medicine, 151(9), 639-649. Retrieved from http://annals.org/aim/article/745155/hormonal-testing-pharmacologic-treatment-erectile-dysfunction-clinical-practice-guideline-from