Is a stable or decreasing prolactin level in a patient with prolactinoma a surrogate marker for lack of tumor growth?

Abstract

The optimal interval for follow-up imaging of patients with prolactinomas is unclear. We wish to determine the likelihood of tumor enlargement in patients with prolactinomas who have a stable or reduced prolactin (PRL) level over time, whether or not they are treated with a dopamine agonist (DA). We identified 80 patients with prolactinomas (34 men, 46 women) who had at least two paired sets of serum PRL levels and pituitary MRIs, 3 or more months apart. Patients with hyperprolactinemia due to drug or stalk effects were excluded. The median (range) age was 45 (25-77) years. Sixty-three patients (78.8%) were treated with DA. PRL levels (ng/mL) at the initial and latest sets were 114 (0.3-15,732) and 16 (0.3-1,204), respectively. In patients with identifiable tumors, the maximum tumor diameters (mm) at the initial and latest MRI studies were 12.5 (2-60) and 12.5 (2-39) respectively, with an interval of 2.9 (0.3-9.7) years. Sixty percent of patients (n = 48) had a macroadenoma. Forty-two (52.5%) patients had either disappearance of the tumor (n = 22) or reduction (n = 20) in tumor size. In the remainder, tumor size was stable in 35 but increased in 3 patients. One of these patients, observed off therapy had a concomitant rise in PRL level. The other 2 had evidence of pituitary hemorrhage with no PRL increase. Tumor growth in prolactinoma patients with a stable or decreasing PRL level, regardless of size, is a rare event. Repetitive pituitary imaging in these patients may not be warranted.

Identification of clinical factors related to antibody‐mediated immune response to the subfornical organ

“…Prolactin release is controlled by prolactininhibiting factors, such as dopamine, which is produced in the arcuate nucleus. 30 As the arcuate nucleus also receives neural inputs from the SFO, autoimmune damage in the SFO might cause dysfunction in the arcuate nucleus and dysregulation of prolactin release. Taken together, in patients with adipsic hypernatremia and prolactin levels <120 ng/ml, potential autoimmunity to the SFO should be taken into consideration.…”

Surgical treatment for male prolactinoma

“…The relationship between tumor size and serum PRL level remains controversial. [9] It has been demonstrated that the preoperative PRL level does not correlate with tumor size. Lactotropes and somatotrophs share a common precursor cell; [10] therefore, the overgrowth of precursor cells may lead to GH-PRL mixed adenomas.…”

Italian Association of Clinical Endocrinologists (AME) and International Chapter of Clinical Endocrinology (ICCE). Position statement for clinical practice: prolactin-secreting tumors

“…At variance, in MP in case of PRL levels Although there is a clear correlation between size of adenoma and PRL levels (57,58,59) before and after treatment, there are cases of discordance between tumor changes and PRL levels during therapy (94). In most of these rare cases, enlargement of MP during DA therapy with stable/reduced PRL levels is mostly related to pituitary hemorrhage (95). The timing of further MRI follow-up after the first performed at 1-3 months should be based on the individual clinical context, including the changes of neuroophthalmological and endocrinological picture, pre-treatment adenoma size, signs of invasiveness, prior surgery, rate of PRL decline and tumor shrinkage on DA treatment, sex, estrogen state, as well as adherence to the medication (96).…”

“…Enlargement of microP while on DA therapy was reported to be extremely rare (95). This observation has led some experts to recommend not performing follow-up MRI at least for microPs (97) unless PRL rises significantly (e.g., >250 ng/mL), or if severe headache, impairment of visual fields or visual acuity or cranial nerve palsies develop (98,99).…”

“…Enlargement of microP while on DA therapy was reported to be extremely rare ( 96 ). This observation has led some experts to recommend not performing follow-up MRI at least for microPs ( 98 ) unless PRL rises significantly (e.g.…”