Patients with hyperprolactinemia were younger (p=0.006) and more likely to be females (p=0.001), had larger and more invasive pituitary adenomas (p<0.001), and had higher levels of GH (p=0.004) and GH nadir (p=0.003), compared to patients with normal prolactin (Table 2). This evidence concerns the gene GH1 and hyperprolactinemia.