Endocrine Abstracts

Introduction: Hyperprolactinaemia is a common finding in endocrine practice and can be due to a number of causes. The degree of elevation of prolactin levels may sometimes be helpful in distinguishing between underlying aetiology.

Aim: To determine if hyperprolactinaemia is correlated with clinical diagnosis in a cohort of patients in the endocrine service at a tertiary centre.

Methods: A biochemistry database held at University Hospital of Wales, Cardiff, UK, was used to find patients who had prolactin levels requested by the endocrinology department between June 2019 and February 2022. This list was used to identify patients who had hyperprolactinaemia, as defined by serum prolactin levels of Males >407 mU/l and Females >557 mU/l, on at least two occasions. The initial elevated prolactin was noted and clinical records were examined to determine the clinical diagnosis made.

Results: A total of 1198 cases were identified. Out of these, 320 duplicates were removed, leaving 878 patients. 410/878 patients with hyperprolactinaemia were identified. 89 patients with incomplete data were excluded and 62 who only had a single elevated prolactin level measured were also excluded, leaving 259 patients. This cohort had their initial elevated prolactin levels identified between the years 2003 and 2022. 193 females and 66 males were identified. Mean age: 44 (17–91)y. A total of 10 diagnoses had been made, with mean prolactin levels and ranges as follows, in order of frequency of diagnosis: Microprolactinoma (n=111) 1797 (540–12 488)mU/l, macroprolactinoma (n=40) 26 776 (1330–160 452)mU/l, non-functioning pituitary adenoma (NFA) (n=36) 796 (466–1406)mU/l, Drug-Induced Hyperprolactinaemia (DIH) (n=22) 1989 (454–8355)mU/l, polycystic ovary syndrome (n=15) 1137 (628–2223)mU/l, idiopathic (n=15) 1113 (608–2458)mU/l, acromegaly (n=8) 3286 (444–17076)mU/l, stress (n=6) 866 (611–1261)mU/l, craniopharyngioma (n=4) 891 (595–1228)mU/l and empty sella (n=2) 1318 (1208–1427)mU/l. For the more common diagnoses, mean prolactin in microprolactinoma was higher than NFA (P<0.001), but there was no difference in mean prolactin in microprolactinoma compared to PCOS (P=0.15) or DIH (P=0.64). The mean prolactin in macroprolactinoma compared to NFA was statistically significantly higher (P<0.001), and also as compared to microprolactinoma (P<0.001).

Conclusions: A number of aetiologies result in elevated serum prolactin concentrations. Our data show hyperprolactinemia is more commonly found in females patients. Although there was an overlap in ranges between many of the diagnoses, in macroprolactinoma prolactin levels were no less than 1000 mU/l and in NFAs, no greater than 2000 mU/l. Mean serum prolactins were statistically higher in macro- and microprolactinomas compared to NFAs, and macroprolactinomas compared to microprolactinomas.