Needs further evaluation - assessment of sexual development and other Pituitary hormones,CT,MRI
Welcome to XXXXXXX
I have gone through your query and understand your concern.
Now he is suffering from male hypogonadism
As you suspected, he may have Defect in pitutary gland stimulation.
Because he have both High TSH
and low testosterone
But it can also be due to Defect in testes and Hypothyroidism
First thing we have to check is his sexual development such as your pubic hair, muscle mass and size of your testes, is consistent with his age.
because he may be suffering from Undescended testicles.
Next we have to check other pituitary hormone levels.
If they are all subnormal, then he is suffering from pituitary hypogonadism.
He need further investigations like Pituitary imaging Like CT, MRI etc.
Treatment depends on the cause for low testosterone.
Please do the investigations said.
Low vitamin d levels be due to low vitamin consumption like strict vegetarian diet or under exposure to sunlight.
This can easily treated by supplementing the vitamin D and exposure to sunlight.
Hope this helps.
Please write back for further queries.
Wishing you good health.