hyperprolactinaemia

• Hyperprolactinaemia occurs when there is an elevated level of prolactin in the blood
• It is the most common type of hypothalamic-pituitary dysfunction and it is an important condition to consider in young women with fertility issues or irregular menstruation
• The primary function of prolactin is to stimulate breast tissue proliferation during pregnancy and breast milk production post-partum
• Prolactin inhibits luteinising hormone (LH) and follicle-stimulating hormone (FSH) secretion.
• Prolactin secretion is regulated by the hypothalamus, and this is predominantly under inhibitory control by hypothalamic dopamine
• thyrotropin-releasing hormone (TRH), serotonin and oestrogens can act to stimulate prolactin release.
• Physiological causes:

  • Stress
  • Sexual intercourse
  • Pregnancy
  • Lactation
  • Exercise
  • Increases usually temporary
• Drug related causes:

  • Antipsychotics
  • Antidepressants (SSRIs, MOA and tricyclics)
  • Certain antiemetics - domperidone and metoclopramide
  • Opioids
  • Oestrogens
• Pathological causes:

  • Most common = prolactinomas, tumours originating from the lactotroph cells of the anterior pituitary gland
  • Other masses of the pituitary or hypothalamus that compress the pituitary stalk
  • CKD
  • Cirrhosis
  • PCOS
  • Hypothyroidism
  • Sarcoidosis
• Symptoms due to the direct effects of raised prolactin:

  • Amenorrhoea (absence of period)
  • Oligomenorrhea (infrequent)
  • Infertility
  • Galactorrhoea (milk production from the breast)
  • Reduced libido
  • Erectile dysfunction in men
• Symptoms due to tumour:

  • Headache
  • Visual disturbances
  • Other pituitary deficiencies or excess
• Important areas to cover in history:

  • Obstetric history: current or recent pregnancy; history of infertility
  • Menstrual history
  • History of hypothyroidism, renal or liver disease
  • Drug history: to identify any drugs that may cause hyperprolactinaemia
  • Family history: about 20% of patients with multiple endocrine neoplasia type 1 (MEN1) have prolactinomas
• Clinical exam:

  • Visual field defects: classically bitemporal hemianopia (caused by a pituitary adenoma compressing the optic chiasm)
  • Cranial nerve palsies
  • Gynaecomastia
  • Galactorrhoea
  • Clinical signs associated with concomitant dysfunction of other pituitary hormones (e.g. change in appearance and interdental spacing in acromegaly)
  • Clinical signs of underlying systemic disorders (e.g. hair loss, bradycardia in hypothyroidism)
• Lab investigations:

  • Serum prolactin - to confirm diagnosis
  • Pregnancy test
  • TFTs to identify hypothyroidism
  • U&Es to identify CKD
  • Pituitary function testing
• An MRI pituitary is used to investigate for a pituitary adenoma or hypothalamic mass. 
• Dopamine agonists are the first line treatment of macroprolactinomas and microprolactinomas.

  • Lower prolactin levels, shrink tumour size and restore normal gonadal function
  • Cabergoline and bromocriptine
• Transsphenoidal surgery is usually indicated for those patients who are resistant to dopamine agonists or cannot tolerate the side effects. However, the cure rate with surgery for macroprolactinomas is poor at about 30%
• Hypogonadism secondary to hyperprolactinaemia can lead to:

  • Infertility and erectile dysfunction
  • Osteoporosis: spinal bone density is decreased by roughly 25% in women with hyperprolactinemia