Endocrine Abstracts

Introduction: Prevalence of prolactinoma is approximately 10/100,000 (men) and 30/100,000 (women) and dopamine agonists remain pharmacological treatment of choice. Cabergoline, an effective dopamine agonist, is preferred due to better tolerability withhigher efficacy in lowering prolactin and reducing tumour size in comparison with bromocriptine. Digital vasospasm, known adverse effect of Bromocriptineis mediated by activation of α1 adrenergic receptors. It’s rarely reported with Cabergoline. We describe a case of cabergoline induced Raynaud’s phenomenon in a woman with microprolactinoma necessitating medication stoppage.

Case: A 34-year-old non-smoker referred to Endocrine clinic with incidental high prolactin (1140Mu/l) during assessment of sub-fertility. Rest of pituitary hormone profile being unremarkable, subsequent pituitary MRI confirmed pituitary micro-adenoma (5x3mm) and started on Cabergoline 250 mg twice/week and then reduced to weekly. Prolactin levels normalised on Cabergoline. 2-years following initiation of treatment, (during the pandemic) shenoticed gradual onset of numbness with pins and needles, discolouration of second and third toes of her feet that turned yellow/white in cold weather. She reported it to us 2 years later with nocomplaints with hands. Foot warmers and putting feet in warm water relieved her symptoms. No other clinical findings or risk factors were identified. Rheumatology work up with autoimmune screen (ANA, ENA, antidsDNA, ANCA, anti-Yo, anti-Hu and anti-Ri antibodies) were negative. Clinical diagnosis was Raynaud’s phenomenon secondary to Cabergoline with symptoms resolving 1-2 months after stopping Cabergoline. Currently 15-months post cessation of drug no symptoms have recurred with serum prolactin levels 683 mu/l (query secondary to Sertraline) and stable size of microadenoma. On literature review, our case developed Raynaud’s at the minimal dose of 250 mg weekly.

Conclusion: Raynaud’s phenomenon a rare side effect of Cabergoline that normally comes on within 5-10 years post treatment should be taken into consideration with co-existent autoimmune conditions when clinical presentation merits.