Any of those potential causes might interfere with normal hormone production, but so far none of them have been proven as a definite cause.

FORBES: Study Shows that Early Puberty is Now Affecting Boys, Just Like Girls

Sometimes it is a normal gene that directs the production of a hormone, such as insulin, or of the cell machinery which that hormone stimulates, such as the insulin receptor.

FORBES: A hail of silver bullets

If a pituitary tumor has resulted in decreased hormone production, or if removal of a pituitary tumor has lowered hormone production, you may need to take replacement hormones to maintain normal hormone levels.

CNN: Pituitary tumors