It could be a combo of both... Your TT is that of a 90yr old...however, your LH/& FSH are at the lower end of range so it's tough to say w/out getting an MRI on your pituitary to see if you have an adenoma... Or an ultrasound on your testes of even to see if you respond to the hCG... It doesn't have to be one or the other(thx Bizzarro

) - although some have it that way...
I would suggest a full thyroid(w/TSH AND FT3/& FT4), prolactin, full Lipids, CMP, PSA, basically a full male hormone panel - but add in prolactin and Free T3/4(on thyroid)
Simon whatcha think... Looking at his pituitary and his TT?