What are the key clinical features that suggest a diagnosis of prolactinoma in a patient presenting with hyperprolactinemia?

Key clinical features suggesting a diagnosis of prolactinoma in a patient with hyperprolactinemia include:

• Galactorrhea: Spontaneous or provoked milk secretion unrelated to childbirth or nursing is a hallmark feature, reflecting elevated prolactin levels affecting breast tissue Sakiyama & Quan 1983.
• Menstrual disturbances in women: Oligomenorrhea or amenorrhea due to prolactin-induced suppression of gonadotropin-releasing hormone, leading to hypogonadism Breil et al. 2018.
• Infertility: Resulting from disrupted hypothalamic-pituitary-gonadal axis function Breil et al. 2018.
• Sexual dysfunction in men: Reduced libido and erectile dysfunction caused by hypogonadism secondary to hyperprolactinemia Pekić et al. 2019.
• Headache and visual field defects: Particularly bitemporal hemianopia, indicating mass effect from macroprolactinomas compressing the optic chiasm (NG guidelines NICE NG132).
• Other symptoms of hypopituitarism: Fatigue or symptoms related to other pituitary hormone deficiencies may be present if the tumour is large (NG guidelines NICE NG132).

These features, combined with markedly elevated serum prolactin levels, especially when levels exceed 2000 mIU/L, strongly suggest prolactinoma rather than other causes of hyperprolactinemia (NG guidelines NICE NG132; Breil et al., 2018). Clinical context and imaging with pituitary MRI are essential to confirm the diagnosis and assess tumour size and impact (NG guidelines NICE NG132).