What happens if the pituitary produces too much or too little hormone?

It depends: It depends on which hormone we are discussing. Effects ranging from gigantism/dwarfism, to inability to get pregnant are possibilities. So, it is difficult to say without knowing specifically which hormone we are concerned with. The six hormones produced by the pituitary are: fsh, LH (control sex hormones), gh (growth), TSH (thyroid), acth (adrenal), and prolactin (milk).

Depends: Unless there is a secreting pituitary tumor the pituitary gland will not over secrete. Under production depends on the hormones not produced in sufficient quantity. Low testosterone, infertility, low thyroid, low cortisone are all possibilities.