PRL and hyperprolactinemia: In cases of nonfunctioning pituitary adenomas, hyperprolactinemia is usually much milder (most cases have prolactin levels < 100 ng/mL) as it is thought to mainly result from stalk compression that hampers the suppression of lactotrophs by dopamine, and not from prolactin hypersecretion, as it occurs with prolactinomas (1,2,18-20).