Mild concomitant hypercalcemia in accordance with familial hypocalciuric hypercalcemia (FHH) prompted mutation analysis of the calcium receptor (<i>CASR)</i> gene which yielded a pathogenic inactivating variant.<h4>Discussion/conclusion</h4>The presence of two separate prolactinomas in a patient with KS has not yet been reported in the literature. Here, CASR is linked to familial hypocalciuric hypercalcemia.