Hyperprolactinaemia needs to be considered in any patient who presents with abnormal galactorrhoea or any of the other symptoms discussed previously. A blood test can detect pathologically high levels of prolactin. The most common pathological cause of high prolactin levels are adenomas (benign tumours) of the pituitary.
When prolactin levels are above 1500mU/l then imaging of the pituitary and hypothalamus is essential. Either a high resolution CT scan or MRI scan are used for the diagnosis and to plan any surgery.
As prolactinomas can form part of the Multiple Endocrine Neoplasia syndromes (MEN1), a routine serum calcium (hyperparathyroidism) can help rule out this diagnosis.
Thyroid function tests are also investigated to rule out hypothyroidism as a possible cause.