Relapsed Hyperprolactinemia with No Evidence of Pituitary Tumor in a Woman with a History of Pituitary Microadenoma

We present a case of hyperprolactinemia in a woman with a history of pituitary microadenoma detected by magnetic resonance imaging (MRI) of the brain 5 years ago and was treated with cabergoline. After medication discontinuation, prolactin level started increasing without any evidence of the pituitary tumor in follow up MRIs.

Case Description :

A 51-year-old woman with a past medical history of pituitary adenoma of 5 mm (diagnosed 5 years ago) presents to the clinic for follow-up. She has low sex drive. She denies vision change, infertility, galactorrhea, and use of antipsychotics and marijuana. She has no history of infertility and has a daughter.

She presented 5 years ago with irregular menstrual cycles and was diagnosed with hyperprolactinemia due to pituitary microadenoma detected on MRI of the sella.

Due to concern for irregular cycles and elevated prolactin, cabergoline was initiated. Her prolactin level and cycles were normalized. While on cabergoline, no microadenoma was detected on MRI of the sella after 2 years of treatment. The cabergoline was gradually tapered down and stopped. She became amenorrheic and her prolactin level increased one year after cabergoline discontinuation. However, follow-up MRIs of the sella for the last 3 years were negative for the pituitary microadenoma. Her prolactin level varied between 263- 310 ng/ml (5.0-23.0 ng/ml), macroprolactin level was 13 % ( < 60%) thyroid, renal, liver function, c-reactive protein, ESR, anti-ANA, anti-CCP, anti-dsDNA, and RF were normal and urine drug screen was negative. The patient had a normal colonoscopy, mammogram, and bone densitometry results. Estrogen level was at the postmenopausal range, LH and FSH levels were inappropriately normal.

Discussion :

Hyperprolactinemia usually causes galactorrhea, decreased libido, infertility, vision change, and fatigue. Treatment of hyperprolactinemia due to microadenoma is with dopaminergic agents. Withdrawal of the treatment can be considered if the prolactin level is normal at least for 2 years and adenoma is not seen on MRI. However, in some studies, it is shown that recurrence of hyperprolactinemia can occur in 31 percent of the time 2-5 years after treatment withdrawal. Regrowth of microadenoma was not observed within 2-5 years after medication withdrawal. Gonadal dysfunction may redevelop as well. The length of that study was not long enough to say how long it may take the microadenoma to regrow.

Pituitary microadenoma is usually asymptomatic and galactorrhea is rare in postmenopausal women and can be recognized only if macroadenoma or its complications occur. We recommend patients with hyperprolactinemia and no tumor recurrence need to be monitored closely with brain imaging.