Endocrine Abstracts

Prolactinoma is the most frequent pituitary tumour among women of childbearing age. Cabergoline (CAB) is the treatment of choice for most of these patients. However there remain prolactinomas completely or partially resistant to standard therapy, which is rare in microprolactinomas. We present a clinical case demonstrating a positive change of the response to treatment of partially resistant microprolactinoma. A female patient, born in 1989, initially presented with dysmenorrhea/galactorrhea at the age of 18 yrs. Elevated prolactin (PRL) level of 150 ng/ml (upper limit of normal ≤ 25 ng/ml) and microadenoma of 8 mm in maximal size at pituitary MRI were revealed. The diagnosis of microprolactinoma was established and CAB was initiated at 0.25 mg twice weekly. PRL was reduced but its normalization was not achieved despite stepwise titration of CAB dose up to 4.0 mg/week. PRL varied from 770 to 1294 mIU/l (upper limit of normal ≤ 557 mIU/l, macroprolactinemia was excluded). Maximal adenoma size increased to 10 mm. In 2011-13 she was taking 4.5-5.0-4.5 mg/week regularly, but PRL remained elevated (856-800-618 mIU/l). In December 2013 she got pregnant at dose of 4.5 mg/week. CAB was discontinued, but spontaneous abortion occurred at 8–9 weeks of pregnancy. CAB was restarted at the same dose with much more pronounced effect. Achieving of normal PRL level had made it possible to reduce the dose to 2.5 mg/week. In July 2014 she got pregnant for the second time. CAB was discontinued again. No complications during pregnancy were observed, and a healthy male infant was delivered at term in 2015. After cessation of breastfeeding moderately elevated PRL and some reduction of maximal adenoma size (to 6 mm) were registered. CAB was restarted and PRL was controlled on standard dose of 1.0 mg/week. In 2018 she became pregnant for the third time. CAB has been cancelled. The fetal growth to date is appropriate for gestational age. Only a few studies have addressed the outcome of prolactinoma after pregnancy pointing the remission (mostly of microprolactinomas) after delivery in some patients. This case (11 yrs of follow-up) demonstrates a better response to CAB of partially resistant microprolactinoma in a compliant patient after the first pregnancy despite its unsuccessful outcome. After miscarriage hyperprolactinemia has been controlled on standard doses of CAB resulting in restoration of fertility, subsequent pregnancies and some reduction of microadenoma size after delivery and cessation of breastfeeding.