16th September 2024

Investigations

Diagnosing a prolactinoma involves elevated prolactin levels and MRI evidence of a pituitary mass. Macroadenomas are detectable, while microadenomas are often not visible. Prolactin levels help determine the aetiology.

• A prolactin level of 1000 – 3000 mU/l is likely to be medication induced, hypothyroidism and physiological reasons listed above.
• A prolactin level >3000 mU/l is suggestive of a microprolactinoma or medication induced.
• A prolactin level >6000 mU/l is indicative of a macroprolactinoma.

Generally, higher prolactin levels correlate with larger adenomas. Measuring TRH can also be helpful as it stimulates prolactin secretion.