Definition of late-onset hypogonadism (LOH): A clinical and biochemical syndrome associated with advancing age and characterized by typical symptoms and a deficiency in serum testosterone levels. It may result in significant detriment in the quality of life and adversely affect the function of multiple organ systems.1
A short review on LOH 
A study about the urological perspective of LOH
Reference:
1. Investigation,Treatment and Monitoring of Late-Onset HypogonadisminMales ISA, ISSAM, and EAURecommendations - E. Nieschlaga,* R. Swerdloffb, H.M. Behrec, L.J. Goorend, J.M. Kaufmane, J.-J. Legrosf, B. Lunenfeldg, J.E. Morleyh, C. Schulmani, C. Wangj, W. Weidnerk, F.C.W. Wul