Investigation of Hyperprolactinaemia	

In practice, it is important to exclude both hypothyroidism and the ingestion of drugs that either deplete central dopamine or block dopamine receptors as causes of hyperprolactinaemia. Having excluded these two causes, three diagnostic possibilities remain: the patient may have:
• A microadenoma
• A macroadenoma
• No tumour at all. 
If hypothyroidism and the ingestion of drugs have been ruled out, and patients with hyperprolactinaemia do not harbour an  identifiable tumour, they are described as having idiopathic  hyperprolactinaemia. 

See later:
• Radiology of the Pituitary Fossa
• Microadenomas in Hyperprolactinaemia
• Macroadenomas in Hyperprolactinaemia