As cutt said, a Dr or a lab. You can order tests online, where you can send them to a lab yourself, but they are mostly saliva tests, and its a pain to fill a whole vial with siliva first thing in the morning when you wake up. Much easier to just go to your dr, or any random dr, and tell them you want some bloodwork done to check your test.. they usually want to know why, so justr give them the general symptons for low test, and they should be fine with that.
There are online blood testing companies, where you go and get your blood drawn at a Labcorp. I cannot remember the name of them right now, but I am sure a google search would pull it up.
There are online blood testing companies, where you go and get your blood drawn at a Labcorp. I cannot remember the name of them right now, but I am sure a google search would pull it up.