Practice Rational testing

Interpreting raised serum prolactin results

BMJ 2014; 348 doi: https://doi.org/10.1136/bmj.g3207 (Published 23 May 2014) Cite this as: BMJ 2014;348:g3207
  1. Andy Levy, professor of endocrinology and honorary consultant physician
  1. 1Henry Wellcome Laboratories for Integrative Neuroscience and Endocrinology, Dorothy Hodgkin Building, University of Bristol, Bristol BS1 3NY, UK
  1. Correspondence to: A Levy mdal{at}bris.ac.uk
  • Accepted 4 April 2014

The author explores how doctors in primary care can identify, investigate, and refer patients with hyperprolactinaemia

Learning points

  • Prolactin is a stress hormone. Transient concentrations double the upper limit of the reference range are common

  • Antipsychotic drugs and treatments for nausea are common causes of hyperprolactinaemia

  • Prolactin concentrations over 3000 mIU/L suggests the presence of a prolactinoma

A 29 year old woman working in a solicitor’s office presented with secondary amenorrhoea and was found to have a serum prolactin concentration of 2940 mIU/L (upper reference limit <600) and thyroid stimulating hormone (TSH) concentration of 5.2 mIU/L (reference range 0.27-4.2 mIU/L). She had a history of depression and had previously been treated for anxiety and hyperthyroidism. There was no history of acne or hirsutism, and, until eight months before presentation, her periods had been regular. Her body mass index (BMI) was 18 compared with 19.8 the previous year.

What is the next investigation?

A more detailed history would be useful.1 In particular, ask about:

  • Possible symptoms of hyperprolactinaemia, such as nipple discharge and galactorrhoea (or in men, reduced libido and new onset erectile dysfunction)

  • Possible causes of hyperprolactinaemia—for example,

    • Pregnancy and breastfeeding

    • Drugs, as many commonly used drugs increase prolactin concentrations (figure)

    • Stressful events and excessive exercise

    • A history of renal insufficiency.

Symptoms and typical diagnoses of hyperprolactinaemia according to circulating concentrations of prolactin. Most laboratories routinely exclude macroprolactinaemia when a raised prolactin concentration is encountered, but where this is not routine, it might need to be requested

The patient had re-started taking citalopram three months earlier because of a recurrence of depressive symptoms that had considerably impaired her performance at work. Previous management of her thyrotoxicosis had rendered her hypothyroid, and she agreed that she often forgot to take the levothyroxine prescribed. She took no other drugs or over the counter remedies. Review appointments were …

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