Recurrent kidney stones should include hyperparathyroidism on your differential, couple that with gastrinoma and you’re looking at MEN 1. Lipomas are also associated with MEN 1.
This question was asking about the adverse effects of proton pump inhibitors especially given previous kidney issues. PPIs decrease serum Mg and serum Ca absorption and can increase the risk of fracture (especially in the elderly).
The pituitary tumors in MEN 1 are prolactin or GH, so Calcium levels, for Parathyroid adenomas, would be the best answer.
When you see a pancreatic endocrine tumor in combination with other weird findings, always think MEN 1
Why would you not check cortisol, if you're worried for MEN1? I assumed high calcium was implied based on the renal stones