The Chi-square tests carried out between every two subtypes of pituitary adenomas indicated that the proportional ratio of six hPRL variants was significantly different between every two subtypes of pituitary adenomas (p < 0.05), except for no significant difference between subtypes FSH+/LH+ and PRL+, and between subtypes FSH+ and PRL+. Here, PLOD1 is linked to pituitary gland adenoma.