Endocrine Abstracts

Macroprolactin is a bio-inactive molecule which cross-reacts in prolactin immune-assays. ‘Macroprolactinaemia’ describes hyperprolactinaemia which is entirely explained by the presence of macroprolactin. Failure to recognize macroprolactinaemia is associated with inappropriate investigation and unnecessary treatment. While screening for macroprolactinaemia is regularly undertaken in the UK and Ireland and to a lesser extent in continental European and Japan, this is rarely performed in the USA. Based on information supplied by the College of American Pathologists it is estimated that 5–10% of hyperprolactinaemia in the USA is due to macroprolactinaemia. The Endocrine Society guideline for ‘Diagnosis and treatment of hyperprolactinaemia’ recognizes that 45% of macroprolactinaemic patients have oligo-/amenorrhoea. However, the guideline recommends that screening for macroprolactin should be limited to ‘asymptomatic hyperprolactinaemic subjects’! (Melmed et al. J Clin Endocrinol Metab 2011 96 273–288). Prompted by this recommendation a letter to the Editor from an international group of experts on macroprolactin was published on line (Fahie-Wilson et al. Published 14 Jan 2013). The letter requests that the guideline dealing with macroprolactin be revised to conform with published evidence. A recent review article (Klibansky. Prolactinomas. N Engl J Med 2010 362 1219–1226) noted macroprolactinaemia but concluded that ‘such occurrences are rare’. The author cited Gibney et al. 2005, to support this claim although this publication reports that 22% of hyperprolactinaemic patients had macroprolactinaemia! (The impact on clinical practice of routine screening for macroprolactin. J Clin Endocrinol Metab 90 3927–3932). A letter to the Editor indicating this error was not accepted for publication, but subsequently under ‘corrections’ it was noted the phrase ‘such occurrences are rare’ should not have been included (N Engl J Med 2010 362 2142).

This presentation will explore why these differences in trans-Atlantic medical practices exist and discuss potential approaches to bring about change to improve patient care.