Searchable abstracts of presentations at key conferences in endocrinology
Endocrine Abstracts (2010) 21 P289

SFEBES2009 Poster Presentations Pituitary (65 abstracts)

A fall in serum prolactin level after a 2-h rest predicts a normal MRI in patients using dopamine antagonist treatment

Martin Whyte , Matthew Allum , Sesha Pramodh & Simon Aylwin


King’s College Hospital, London, UK.


Introduction: Hyperprolactinaemia associated with antipsychotic drug use is a commonly encountered clinical problem, yet no decision-making tools exist to guide whether to scan the pituitary gland.

Methods: A 10-year data series was reviewed of 246 patients who were evaluated for prolactin excess with a cannulated prolactin study. All patients had a prolactin drawn immediately following the insertion of a forearm cannula (P1) and a second sample drawn after 120 min bed rest (P2).

Comparison was made between patients with a confirmed microprolactinoma (galactorhoea and/or oligomenorrohea with resting hyperprolactinaemia and microadenoma on MRI) against those on dopamine antagonists as well as normal controls.

The presence of macroprolactin was excluded in all samples.

Results: Sixteen patients out of 246 were on dopamine antagonists. In eight patients the prolactin normalised following discontinuation of the drug for at least 3 weeks.

Number of subjectsP1 (mU/l)P2 (mU/l)ΔP (%)
Normal controls25703.4±35.2347.3±22.7−47.2±4.7
Microprolactinoma541873.8±179.31718.7±163.9−4.4±1.6
Dopamine antagonist use and normal MRI62918.2±672.31588.0±257.5§−45.6±9.5*
Dopamine antagonist use and microadenoma21201.0±235.01229.5±270.5+1.6±2.4
*P≤0.001 versus microprolactinoma; =0.04 versus dopamine antagonist and microadenoma; P≤0.001 versus normal controls; §<0.05 versus normal controls.

Conclusion: In our series, prolactin normalised after 2 weeks of cessation of dopamine antagonists, when treatment could safely be discontinued. A fall after 2 h rest predicted a normal MRI in patients continuing on dopamine antagonists.

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