From the Guidelines
For a male with prolactinoma, the next step is typically treatment with dopamine agonist medication, most commonly cabergoline starting at 0.25mg twice weekly and gradually increasing to 0.5-1mg twice weekly as needed, as it has been shown to be effective in reducing serum prolactin concentrations and inducing tumour shrinkage 1.
Key Considerations
- Treatment aims to normalize prolactin levels, reduce tumor size, and restore testosterone levels and sexual function.
- Before starting medication, baseline tests should include:
- Prolactin levels
- Pituitary hormone panel
- Testosterone levels
- Visual field testing if the tumor is large
- Most prolactinomas respond well to medication within weeks to months, with tumor shrinkage often occurring within 3 months.
Monitoring and Follow-up
- Regular monitoring of prolactin levels every 1-3 months initially is important, along with MRI follow-up at 3-6 months to assess tumor response.
- Surgery is generally reserved for cases resistant to medication or with acute complications like visual impairment.
Dopamine Agonist Therapy
- Cabergoline is the dopamine agonist of choice given its superior effectiveness and lower adverse effect profile 1.
- Bromocriptine is an alternative option, usually starting at 1.25mg daily and increasing to 2.5mg two to three times daily.
- For patients resistant to standard doses of cabergoline, graduated dose increments of up to 3.5 mg per week or up to 7 mg per week in exceptional cases may be considered 1.
From the FDA Drug Label
Bromocriptine mesylate tablets, USP treatment is indicated in patients with prolactin-secreting adenomas, which may be the basic underlying endocrinopathy contributing to the above clinical presentations. Reduction in tumor size has been demonstrated in both male and female patients with macroadenomas In cases where adenectomy is elected, a course of bromocriptine mesylate tablets, USP therapy may be used to reduce the tumor mass prior to surgery.
Next Steps for Prolactinoma in Males:
- Medical Therapy: Bromocriptine mesylate tablets may be used to treat prolactin-secreting adenomas, reducing tumor size and hyperprolactinemia.
- Surgery: In cases where adenectomy is elected, bromocriptine mesylate therapy may be used to reduce tumor mass prior to surgery.
- Monitoring: Patients should be monitored closely for signs and symptoms of tumor expansion or other complications, such as visual field impairment 2.
- Alternative Procedures: If evidence of tumor expansion develops, discontinuation of treatment and alternative procedures should be considered 2.
From the Research
Diagnosis and Treatment of Prolactinoma in Males
- Prolactinomas in males are usually large and invasive, presenting with signs and symptoms of hypogonadism and mass effects, including visual damage 3.
- If serum prolactin levels are above 200 microg/L, a prolactin-secreting pituitary adenoma (prolactinoma) is the underlying cause 4.
- Medical treatment with dopamine agonists, such as cabergoline, is the preferred first-line treatment for male prolactinomas, leading to prolactin normalization in ~80% of treated men, and tumor shrinkage, improved visual fields and recovery of hypogonadism in most patients 3.
Treatment Options
- Dopamine agonists, such as cabergoline, are the cornerstone of treatment for prolactinomas, with cabergoline being superior to bromocriptine in prolactin normalization and tumor shrinkage 5.
- For patients who do not respond to dopamine agonist therapy, surgical resection of the prolactinoma is an option 4, 6.
- Radiotherapy may be considered for patients who harbor aggressive prolactinomas 7.
- Experimental treatments, such as temozolomide, may improve clinical response in men harboring resistant prolactinomas 3, 7.
Management of Dopamine Agonist-Resistant Prolactinoma
- The management of drug-resistant prolactinomas includes switching to cabergoline, dose escalation of cabergoline, and transsphenoidal neurosurgery 7.
- Echocardiographic monitoring is advised in patients taking high doses of cabergoline due to the potential association with cardiac valvular fibrosis 7.
- Complete resistance to cabergoline is infrequent, and temozolomide may be a therapeutic option in malignant/aggressive prolactinomas 7.