PARATHYROID HORMONE‐LIKE BIOACTIVITY IN A PATIENT WITH SEVERE OSTEITIS FIBROSA CYSTICA DUE TO MALIGNANCY: RENOTROPIC ACTIONS OF A TUMOUR EXTRACT AS ASSESSED BY CYTOCHEMICAL BIOASSAY

Abstract

A patient is descibed with malignancy, hypercalcemia and radiological evidence of severe parathyroid bone disease, but undetectable concentrations of circulating immunoreactive PTH [parathyroid hormone]. Autopsy showed the tumor to be a metastatic bronchial carcinoid, with no evidence of primary parathyroid disease. Extracts of the tumor had no PTH immunoreactivity, but they had high concentrations of a substance with activity identical to PTH in a cytochemical bioassay. The biological activity of the extract was not inhibited by PTH antibodies, but was inhibited by an antagonist to PTH bioactivity.