There are several mechanisms through which cancer can lead to hypercalcemia:
Humoral Hypercalcemia of Malignancy (HHM): This is the most common cause, where tumor cells secrete parathyroid hormone-related protein (PTHrP), which mimics the action of parathyroid hormone (PTH) and increases calcium levels. Bone Metastases: Cancers that metastasize to the bone can cause local bone resorption, releasing calcium into the bloodstream. Vitamin D production by tumors: Some tumors can produce active vitamin D, which increases calcium absorption from the gut. PTH secretion: Rarely, tumors can secrete actual PTH.
