The most common risk is damage to the normal pituitary gland. For macroadenomas (>1cm) this happens between 5-10% of the time when the operation is performed by an expert pituitary surgeon. This means that new hormone replacement might be required after the surgery, possibly including thyroid hormone, cortisol, growth hormone, estrogen or testosterone. Damage to the posterior, or back portion, of the pituitary gland may produce a condition known as diabetes insipidus, which will lead to frequent urination and excessive thirst, since the kidneys will no longer adequately concentrate the urine. This can be controlled with a nasal spray or pill form of a medication called DDAVP. Permanent diabetes insipidus occurs 1-2% of the time after pituitary surgery.
