PRL and adenoma: Among those with hyperprolactinemia (n=207), patients with prolactin-negative adenomas (n=117) had larger tumors (p=0.003), and their tumors were more likely to invade into cavernous sinus (p=0.004) and sphenoidal sinus (p=0.003), compared to the patients with prolactin-positive adenomas (n=90).