SummaryCo-secretion of growth hormone (GH) and prolactin (PRL) from a single pituitary adenoma is common. In fact, up to 25% of patients with acromegaly may have PRL co-secretion. The prevalence of acromegaly among patients with a newly diagnosed prolactinoma is unknown. Given the possibility of mixed GH and PRL co-secretion, the current recommendation is to obtain an insulin-like growth factor-1 (IGF-1) in patients with prolactinoma at the initial diagnosis. Long-term follow-up of IGF-1 is not routinely done. Here, we report two cases of well-controlled prolactinoma on dopamine agonists with the development of acromegaly 10–20 years after the initial diagnoses. In both patients, a mixed PRL/GH-cosecreting adenoma was confirmed on the pathology examination after transsphenoidal surgery (TSS). Therefore, periodic routine measurements of IGF-1 should be considered regardless of the duration and biochemical control of prolactinoma.Learning points:Acromegaly can develop in patients with well-controlled prolactinoma on dopamine agonists.The interval between prolactinoma and acromegaly diagnoses can be several decades.Periodic screening of patients with prolactinoma for growth hormone excess should be considered and can 
lead to an early diagnosis of acromegaly before the development of complications.

No abstract

Corticotropin stimulation test (CST) is commonly used to diagnose secondary adrenal insufficiency. We present two patients who underwent transsphenoidal pituitary surgery for pituitary macroadenoma. Both patients had additional pituitary hormone deficiencies before and after the surgery. The patients were maintained on glucocorticoid (GC) replacement for at least 3 months after the surgery. In the remote follow-up period, they underwent conventional CST with resultant cortisol levels above 18 μg/dL. This led to discontinuation of GC treatment. Few months later, both patients developed clinically evident adrenal insufficiency. Providers should be cautious interpreting the results of CST in patients with pituitary disorders. The 250-μg CST with standard cortisol cutoff has low sensitivity and can give falsely reassuring results. Thus, it is prudent to use a higher cortisol threshold to define intact hypothalamic-pituitary-adrenal axis.