Three links, two in the Express (a popular UK based newspaper) and a review of many medical articles from Pubmed (third link):

http://www.express.co.uk/life-style/health/626584/male-pattern-balding-premature-hair-loss-prevention-dangerous-life-threatening-health

http://www.express.co.uk/life-style/health/841366/hair-loss-erectile-dysfunction-transplant-treatment-medication-finasteride-alopecia-bald

https://www.ncbi.nlm.nih.gov/pubmed?linkname=pubmed_pubmed&from_uid=26010505