Management of Hyperprolactinemia
For this patient with prolactin of 110 μg/L, initiate cabergoline as first-line therapy after excluding secondary causes (medications, hypothyroidism, renal/hepatic disease) and obtaining pituitary MRI imaging. 1, 2
Initial Diagnostic Workup
Before initiating treatment, complete the following evaluation:
Review all current medications for dopamine antagonists (antipsychotics, antiemetics like prochlorperazine, metoclopramide), antidepressants with serotonergic activity, antihypertensives, and H2-receptor antagonists, as these are among the most common causes of hyperprolactinemia 2, 3
Exclude hypothyroidism by reviewing the TSH result already obtained, as primary hypothyroidism causes hyperprolactinemia in 43% of women and 40% of men through compensatory thyrotropin-releasing hormone hypersecretion 2
Assess renal and hepatic function using the creatinine/eGFR and liver enzyme results already available, as chronic kidney disease causes hyperprolactinemia in 30-65% of patients and severe liver disease is also associated with elevated prolactin 2
Screen for macroprolactinemia in this case of mild elevation (110 μg/L), as it accounts for 10-40% of all hyperprolactinemia cases and represents biologically inactive prolactin complexes that do not require treatment 2, 4
Obtain pituitary MRI with and without contrast to identify prolactinoma versus stalk compression from other masses, as this is the gold standard imaging modality 5
Interpreting the Prolactin Level
This level of 110 μg/L (approximately 2,340 mU/L) suggests either a microprolactinoma or stalk compression rather than a macroprolactinoma, as prolactinomas typically produce levels exceeding 4,000 mU/L in children and adolescents, with similar thresholds in adults 2, 4
If MRI reveals a large pituitary mass (>10mm) with this relatively modest prolactin elevation, request serial dilutions of the serum sample to exclude the "high-dose hook effect," which causes falsely low measurements in approximately 5% of macroprolactinomas due to assay saturation 1, 2, 4
Mild elevations (<100 μg/L or <2,000 mU/L) typically indicate non-functioning adenomas with stalk compression, medications, or other secondary causes, but this patient's level of 110 μg/L is just above this threshold 2
Medical Treatment
First-Line Therapy: Cabergoline
Initiate cabergoline as the dopamine agonist of choice due to superior effectiveness and lower adverse effect profile compared to bromocriptine 1:
Starting dose: 0.25-0.5 mg once or twice weekly, with gradual titration based on prolactin normalization and symptom resolution 1, 6
Conventional doses up to 2 mg/week are typically sufficient for microprolactinomas (<13.5 mm diameter) 1
Cabergoline normalizes prolactin in 83% of patients versus 59% with bromocriptine, and causes fewer adverse events (52% versus 72%) 1
Take with food to minimize gastrointestinal side effects 6, 7
Monitoring During Treatment
Baseline cardiovascular evaluation with echocardiogram is required before initiating cabergoline to assess for valvular disease, as postmarketing cases of cardiac valvulopathy have been reported, particularly with high doses (>2 mg/day) 6
Echocardiographic monitoring every 6-12 months or as clinically indicated for signs of valvular regurgitation, restriction, or leaflet thickening 6
Discontinue cabergoline immediately if echocardiogram reveals new valvular abnormalities 6
Monitor for fibrotic complications including pleural/pericardial effusions, pulmonary fibrosis, and retroperitoneal fibrosis with attention to dyspnea, chest pain, back pain, lower limb edema, or renal insufficiency 6, 7
Repeat prolactin measurement after 3 months to assess biochemical response 8
Repeat MRI after 3 months if macroadenoma is present to verify tumor size reduction, then annually for 5 years, then every 5 years if stable 8
For microprolactinomas, MRI monitoring is not routinely necessary during treatment, but may be performed after 1 year and then after 5 years 8
Alternative: Bromocriptine
If cabergoline is unavailable, contraindicated, or not tolerated:
Bromocriptine 1.25-2.5 mg once or twice daily, titrated gradually 7, 9
Less effective and more poorly tolerated than cabergoline, but has more safety data in pregnancy 9, 10
Monitor blood pressure closely, particularly during the first weeks of therapy, as symptomatic hypotension occurs in almost 30% of patients 7
Special Considerations
Visual Disturbance or Pituitary Apoplexy
Cabergoline remains first-line therapy even with visual disturbance or apoplexy, while carefully monitoring for deterioration in vision, pituitary function, or general status 1
Dopamine agonists resolve visual field defects in 67% of patients with macroadenomas compressing the optic chiasm 2
Pregnancy Considerations
Withdraw cabergoline when pregnancy is diagnosed unless treating a rapidly expanding macroadenoma 7
Bromocriptine is preferred for women actively trying to conceive due to more extensive pregnancy safety data 10
Do not use dopamine agonists in pregnancy-induced hypertension (preeclampsia, eclampsia) unless potential benefit outweighs risk 6
Treatment Duration and Discontinuation
After achieving normal prolactin levels, attempt treatment discontinuation or dose reduction to the lowest effective dose 6, 8
Only 20-30% of patients experience prolactin elevation recurrence after prolonged cabergoline treatment, particularly when no residual adenoma exists 8
Continue monitoring prolactin levels after discontinuation, as levels may rise again after months or years 8
Surgical Indications
Reserve transsphenoidal surgery for: