A microadenoma is described as having a maximum diameter of up to 10mm, and a macroadenoma as having a diameter in excess of this. The normal pituitary diameter does not exceed 10mm. A microadenoma is often visualised using modern computed tomographic (CT) scanning or magnetic resonance imaging (MRI). Usually, the serum prolactin level is below 200ng/ml (4,000mu/l).
