When clinical clues suggest a functional tumor, targeted tests confirm ectopic hormone production: serum cortisol and ACTH for suspected Cushing syndrome9,10; 24-hour urinary 5-HIAA or plasma serotonin for carcinoid syndrome15; growth hormone-releasing hormone and IGF-1 for acromegaly19; serum/urine osmolarity and sodium with ADH for SIADH21; and PTHrP with ionized calcium (occasionally PTH) for PTHrP-mediated hypercalcemia.22 Here, PTHLH is linked to Hypercalcemia.