Quick update: LH and FSH labs came in.
FSH seems normal at 7.7mIU/mL (range is 1.5–12.4)
LH is quite high at 9.0mIU/mL (range is 1.7–8.6)
Current hypothesis is that the microlithiasis is a result of atrophy and not a cause (ruling out calcium regulation issue unless PTH/calcitriol labs come back abnormal).
I also think that the high LH indicates primary hypogonadism rather than secondary.
Still in the dark about a cause, however. The fact that it's only one testicle seems very bizarre. Going to get in with a good urologist to see if they can tell me more. I'll also ask the radiology lab for the ultrasound images and post them here.
In the meantime—any pointers on lowering LH are welcome. I've read that high levels in the blood cause aromatization so will try to ameliorate that.