Safety and Potency of a High Cabergoline Dosage in Microprolactinomas

Inclusion Criteria:

* 1\. Willing and able to provide written informed consent prior to any study-related procedures
* 2\. Adults \>18 years old
* 3\. Pre-menopausal women
* 4\. Presence of signs and symptoms matching prolactinoma
* 5\. Hyperprolactinemia, defined as a prolactin (PRL) level ≥2 times the local laboratory maximum level of normality, present at the time of enrolment
* 6\. Presence of an identifiable pituitary mass on MRI with a maximum diameter of less than 1cm, independently of Knosp/invasiveness of the cavernous sinus
* 7\. Treatment naïve
* 8\. Females who engage in heterosexual intercourse must agree to use either a highly effective or a clinically acceptable method of contraception from the beginning of screening to the last study visit, which will include:
* Hysterectomy or bilateral salpingectomy
* Bilateral tubal occlusion or ligation
* Vasectomized partner
* Intrauterine device (copper or hormonal)
* Progestogen-only contraception (oral, injectable or implantable)
* Male or female condom with or without spermicide
* Sexual abstinence (only when it is the usual and preferred lifestyle of the subject)

Exclusion Criteria:

* 1\. History of primary hyperparathyroidism
* 2\. Use of combined hormonal contraceptive within the past 4 weeks
* 3\. Pregnancy or current pregnancy desire
* 4\. Prolactinoma associated with a known genetic syndrome
* 5\. Familial history of pituitary adenoma
* 6\. Renal failure (estimated glomerular filtration rate \<30 mL/min /1.73m2)
* 7\. IGF-1 level above the age-adjusted normal range of the local laboratory (IGF 1 \>1x ULNR)
* 8\. Idiopathic hyperprolactinemia (normal MRI) or presence of macroprolactinemia
* 9\. Concomitant mental condition rendering her unable to understand the nature, scope, and possible consequences of the study, and/or decompensated psychiatric disease (i.e. gambling or severe obsessive-compulsive disorder), as judged by the Investigator
* 10\. Chronic use of drugs related to hyperprolactinemia (such as metoclopramide, methyldopa, ranitidine, and opioid-related analgesics)
* 11\. Resistant prolactinoma, defined as non-normalization of PRL levels with 2mg/w of CAB
* 12\. Patients in the high dosage group who did not use 3.5mg/w of CAB for an entire 6 months (due to intolerance or non-compliance) or failed to achieve the target dose for any other reason
* 13\. Active malignant disease within the last 5 years, except basal and squamous cell carcinoma of the skin with complete local excision
* 14\. Any decompensated chronic condition (i.e. heart failure NYHA 3-4, diabetes with HbA1c \>8.5%, hypothyroidism with TSH \>10 mIU/L) that, in the opinion of the Investigator, would impede compliance, hinder completion of the study, compromise the well-being of the patient, or interfere with the study outcomes
* 15\. Male sex
* 16\. Cushing stigmas (moon face, muscle weakness, red striation) or suspicious
* 17\. Prior radiotherapy of the pituitary gland area for any reason
* 18\. Additional pituitary tumor-directed therapy, including temozolomide, everolimus, lapatinib, or cytotoxic chemotherapy
* 19\. Hepatopathy with AST/TGO or ALT/TGP \>3x the upper limit of normality