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 and 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 ¹).
• Other symptoms of hypopituitarism: Fatigue or symptoms related to other pituitary hormone deficiencies may be present if the tumour is large (NG guidelines ¹).

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 ¹; 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 ¹).