Parathyroid Hormone–Related Protein and Hypercalcemia Secondary to Massive Mammary Hyperplasia

Abstract
Parathyroid hormone-related protein (PTHRP) is a recently characterized 141-amino acid peptide that is responsible for the humoral hypercalcemia of cancer.1 We previously reported on a patient with massive mammary hyperplasia occurring during pregnancy who had hypercalcemia that resolved after bilateral mastectomy.2 Recent studies done on tissue from this patient implicate PTHRP as the likely etiologic factor in her hypercalcemia.