Elevated expression of GDF15 protein in outer medullary collecting duct cells has been observed in cases of metabolic acidosis and potassium depletion, both of which are linked to decreased kidney function (Fig. 7).[33], [34] Another study also revealed that a rise in prolactin levels was linked to a decrease in kidney function from stages 1 to 5 of chronic kidney disease (CKD) in postmenopausal women.35 Here, PRL is linked to chronic kidney disease.