Endocrine Abstracts

The therapy of hyperprolactinemia with dopamine agonists (DAs) is highly effective in the majority of cases (1). However, some patients fail to achieve normal prolactin levels and develop drug resistance towards prescribed medicine. This case study describes a medical history of The Georgian National Institute of Endocrinology patient, with a drug-resistant hyperprolactinemia and inability to conceive. The patient’s MRI scan result has not indicated incidence of prolactinoma.

The Case Study: A 27-year-old female visited ambulatory clinic with severe headache and amenorrhea. The patient asked to reassess previously prescribed treatment protocol. According to her medical history, she has been diagnosed with hyperprolactinemia and nodular goiter, since she was 14 years old. The patient has been prescribed the dopamine agonist cabergoline (CAB, 0.25 mg, to be taken twice a week). The prolactin levels remain high despite dose escalation. A pituitary MRI with contrast was performed twice: at aged 20 and aged 26. Both scans have not indicated any abnormal lesions. The patient has denied taking any other medicine or recreational drugs.

First ambulatory visit: Prescribed medicine CAB 1.75 mg twice a week (3,5 mg per week). Levothyroxine 25 mg daily. Blood test Showed increased prolactin level - 56,94 ng/ml. (normal range: nonpregnant females: 2 to 29 ng/ml) (2) The blood test was conducted to check hyperprolactinemia level due to non-reactive isoforms. The fraction of polyethylene glycol (PEG)-precipitated (complexed) prolactin was <40 % of total prolactin, therefore the specimen was considered negative for macroprolactin. The further evaluations of pituitary hormones didn’t reveal deviation from the norm. Bromocriptine (2,5 mg) 1/2 pill was added to the patient’s existing prescription.

Second ambulatory visit (after six months): The prolactin level has increased up to 61,10. ng/ml. Updated prescription: Quinagolide 150 mg daily. CAB and Bromocriptine were discontinued due to low efficacy.

Third ambulatory visit: (after three months): regular menses has been restored. On the third regular menstrual cycle, a successful ovulation has been confirmed by appearance and disappearance of a dominant follicle on transvaginal ultrasound (TVUS), performed every third day and by blood test: mid-luteal phase progesterone -12 ng/ml.(3) The prolactin decreased by - 30 ng/ml (1.8–20).

Conclusion: We concluded that partial resistance can be managed by drug shifts, leading to hormonal control of initially resistant patients. As a result the restoration of a normal gonadal axis can be achieved.