PARATHYROID HORMONE-RELATED PROTEIN AS A TUMOR-MARKER IN HUMORAL HYPERCALCEMIA ASSOCIATED WITH OCCULT MALIGNANCY

The tumour-derived factor PTH-related protein (PTHRP) is the primary h umoral factor responsible for hypercalcaemia in patients. with solid t umours. In a woman presenting with anaemia and hypercalcaemia, the fin ding of raised plasma PTHRP and undetectable serum PTH concentrations led to further investigations and the subsequent identification of a u terine tumour. No evidence of tumour spread was found at operation, an d removal of the tumour resulted in normalization of both serum calciu m and plasma PTHRP. Expression of PTHRP by the tumour was shown by imm unohistochemistry and in situ hybridization. We conclude that the iden tification of an occult tumour in a patient with hypercalcaemia and ra ised plasma PTHRP provides evidence of the diagnostic utility of PTHRP immunoassays in the investigation of patients with hypercalcaemia and suspected malignancy.