From Lewis S Blevins Jr. MD – I am often asked how I approach those patients who have “residual hyperprolactinemia” after either surgery, and especially if there is no visible residual tumor on MRI, or during treatment with dopamine agonist drugs. I will share a few thoughts with you here that, hopefully, can guide you and your physicians to further evaluating ad managing this particular problem.
First and foremost, patients fitting this classification should be tested for macroprolactinemia. Macroprolactinemia is a disorder where antibodies are made against the hormone prolactin. Prolactin levels in the bloodstream rise because the large conglomerates of prolactin are not cleared by the kidneys. Total prolactin is elevated but the free prolactin, which is available to the prolactin receptor, is usually normal. Additional treatment is not required in this situation.
In patients who had prolactinomas and underwent surgery, and have postoperative MRI studies that do not show residual tumor, but have elevated prolactin, there are two general considerations. First, many tumors are microscopically invasive and patients often have residual tumor that is just small enough to be below the power of resolution of the MRI scan. Second, some patients may have surgically-induced distortion of the normal anatomy of the hypothalamic-pituitary unit with disruption of the pituitary stalk and what is referred to as stalk hyperprolactinemia. Both groups of patients probably deserve treatment with dopamine agonist drugs to ensure that prolactin is normalized so gonadal function is returned to or maintained normal. Further, in those with residual prolactinomas, treatment should prevent recurrent tumors.
Patients who have failed to normalize prolactin in response to treatment with dopamine agonist drugs Who have not undergone surgery have several options. First, it is imperative to maximize the dose of dopamine agonist drug. In patients taking cabergoline, the dose can be escalated to at least 1.5 mg 2 to 3 times weekly before giving up on treatment. For those taking bromocriptine, the dose can be escalated to about 10 mg three times daily. Those who have failed one drug might try the other. Patients with significant and marked hyperprolactinemia, greater than 200 ng/mL, and whose tumors do not regress in size are considered for surgery to debulk their lesions and increase the likelihood that they will respond to medical treatment. If there is a significant decrease in the size of the tumor, even in the setting of residual hyperprolactinemia, it is often best to except that The response to treatment is incomplete and stay the course with dopamine agonist drugs and consider replacement of sex steroids to treat the hypogonadism that often results from hyperprolactinemia.
Of course, treatment is not always necessary. One may simply follow patients for 6 to 12 months before deciding on any specific plan of action. It is always best to tailor the treatment approach to the particular individual in consideration of the “indications” for treatment. These considerations include, but are not limited to, characteristics of the tumor, degree of hyperprolactinemia, state of gonadal function, and how all of this has affected the patient harboring the tumor.
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