Endocrine Abstracts

Introduction: Prolactinomas are the most common tumors among hormonally active pituitary adenomas. Therapy with dopamine agonists (DA) remains the first treatment choice. However there remain definite numbers of prolactinomas resistant to standard DA therapy. The underlying mechanisms of this phenomenon, management and prognosis are still poorly understood. The search of treatment options for overcoming DA-resistance is an important object in practical endocrinology. We present a clinical case of successful treatment of a man with partially DA resistance with co-administration of quinagolide and cabergolin.

Clinical case: A 58-year-old man presented slight visual impairment, headache and fatigability. Magnetic resonance imaging (MRI) found a endo-infra-suprasellar pituitary adenoma. Laboratory examination revealed hyperprolactinemia (prolactin 4961 IU/l) and secondary hypogonadism. Administration of dopamine agonists (max dose of Cabergolin 5.5 mg per week) led to improvement of visual function and slight decrease of prolactin level (not normalization) with no effect on tumor size on MRI evidence. The decision to add Quinagolide (in max dose 150 μg daily) to therapy was made after 2.5 years of Cabergolin monotherapy. Cabergoline dose was slightly diminished. After 5 months of the combine therapy was observed normalization of prolactin and testosterone level.

Conclusion: This clinical case is an example of successful treatment of partially DA-resistant prolactinoma. The combination of different dopamine agonists allowed to overcome medication resistance and restore gonadal function.