The utility of rested prolactin sampling in the evaluation of hyperprolactinaemia

Abstract

Background and AimsSerum prolactin levels may be elevated by venepuncture stress. We investigated the utility of a rested prolactin sample, obtained through an indwelling venous cannula, in preventing the overdiagnosis of hyperprolactinaemia.MethodsPatients at our institution undergo serial prolactin sampling, usually over 40 min, when investigating hyperprolactinaemia. We retrospectively reviewed all serial prolactin sampling performed during a 3‐year period. Patients with possible medication‐induced hyperprolactinaemia and macroprolactin interference were excluded. We assessed the effect of venepuncture‐associated stress on hyperprolactinaemia with the main outcome being normalisation of serum prolactin at the end of serial sampling.ResultsNinety‐three patients with documented hyperprolactinaemia (range 360–1690 mU/L) were included in the analysis. Prolactin decreased during serial sampling in 73 patients (78%), suggesting a prevalent effect of venepuncture stress. The final prolactin sample was normal in 50 patients (54%), consistent with stress hyperprolactinaemia rather than pathological hyperprolactinaemia. Patients with a referral prolactin result greater than two times the upper reference limit (URL) were less likely (15%) to have a normal prolactin result on serial sampling. Measurement of a single rested prolactin sample from an indwelling cannula showed the same diagnostic utility as serial sampling.ConclusionSerum prolactin results are frequently elevated by the stress of venepuncture. Confirmation of pathological hyperprolactinaemia in a rested sample obtained from an indwelling venous cannula is recommended in patients with mild hyperprolactinaemia, particularly when the referral prolactin is less than two times the URL.

Mild hyperprolactinemia in clinical practice: the diagnostic “traps” and treatment strategy

“…В недавнем ретроспективном исследовании T. Wilkinson и соавт. сравнили уровни пролактина при повторном тестировании и при однократном взятии крови через 40 минут после установки внутривенного катетера у 93 пациентов с умеренной гиперпролактинемией (360-1690 мЕд/л), у которых были исключены макропролактинемия и прием пролактин-стимулирующих препаратов [46]. Уровень пролактина был ниже исходного у 73 (78%) пациентов, полностью нормализовался у 50 (54%), при этом наиболее часто нормализация показателей отмечалась в случае менее чем двукратного превышения верхней границы референсных значений уровня пролактина.…”

Value of cannulated prolactin testing in identifying true hyperprolactinaemia in females of reproductive age

“…2,5,6 Our findings are consistent with a more recent study of 93 patients with referral prolactin concentration of <4 × ULN whereby a 54% prevalence of stress hyperprolactinaemia on cannulated serial prolactin testing was found. 7 Abbreviations: SD: standard deviation of mean. ULN: upper limit of normal (reference) range.…”