It can be from prior injury, testicular failure (they quit working), or loss of signal to tell the testicles to work.
There are many diseases that contribute like diabetes
, pituitary tumors, steroid use and chronic pain
meds. It's more complex than can be listed here. Make sure it's been checked in the morning and if it's really low, see your urologist. For more: www.Peedoc.Com @thepeedoc.