Metoclopramide-Induced Hyperprolactinemia Mimicking Prolactinoma in a Young Woman Receiving Fragmented Care: A Case...

Hyperprolactinemia accompanied by headache and visual symptoms commonly prompts pituitary imaging to rule out prolactinoma. Several medications can elevate serum prolactin into ranges that overlap with prolactin-secreting adenomas, and metoclopramide, a dopamine D2 receptor antagonist used for gastroparesis and nausea, is among the most frequent offenders. Headache and blurred vision are also listed as adverse effects, reproducing the symptomatic triad clinicians associate with a pituitary tumor. We describe a 22-year-old woman with polycystic ovary syndrome who presented with a prolactin level of 160.3 ng/mL, intermittent blurry vision, and chronic headaches managed with onabotulinumtoxinA through neurology. Pituitary MRI was unremarkable. Despite repeated direct questioning, her initial medication history included only losartan. Metoclopramide was identified through deliberate review of outside gastroenterology records, where it had been prescribed for chronic constipation. One month after discontinuation, prolactin levels had returned to normal at 11.2 ng/mL. Menstrual function showed initial improvement, as she experienced her first menstrual cycle after approximately one year of amenorrhea. However, regular menses did not fully resume; cycles remained irregular, likely in the setting of her underlying polycystic ovary syndrome (PCOS). This case illustrates how drug-induced hyperprolactinemia can be missed when the medication list is incomplete, particularly in fragmented care settings, and how deliberate review of outside documentation can spare patients unnecessary imaging.