Low testosterone affects more than 10% of men worldwide, with high incidence in the elderly.This will be a prospective case study. The investigators will identify men with hypogonadism in our clinic interested in Natesto for testosterone replacement therapy (TRT). Natesto is a relatively new form of testosterone replacement therapy that is delivered intranasal to men diagnosed with low testosterone. Current advantages to Natesto include ease of delivery and decreased risk of transference. Recently Natesto 4.5% (125 uL/nostril, 11.0mg testosterone/dose), three times a day (TID) dosing was shown to also increase serum testosterone while maintaining normal, though decreased, serum levels of Luteinizing Hormone (LH) and Follicle-Stimulating Hormone(FSH). 40 participants will be enrolled and receive treatment with Natesto.The study will identify men with confirmed hypogonadism (testosterone (T) <350 on 2 consecutive Testosterone samples collected greater than 1.5 hours apart between 6am and 10am with demonstrated symptoms of hypogonadism). Participants with a history of prostate cancer, testis cancer, azoospermia, or genetic cause of hypogonadism will be excluded.