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Malignancy-associated hypercalcemia: evaluation with a cytochemical bioassay for parathyroid hormone
The Journal of Clinical Endocrinology and Metabolism
|November 1, 1981
Summary
This study utilized a cytochemical bioassay to measure bioactivity in cancer patients. The assay detected elevated levels in hypercalcemic patients, suggesting a novel substance distinct from parathyroid hormone (PTH) involved in malignancy-associated hypercalcemia.
Area of Science:
- Biochemistry
- Endocrinology
- Oncology
Background:
- Malignancy-associated hypercalcemia is a common complication.
- The exact mechanisms and causative agents are not fully understood.
- Parathyroid hormone (PTH) is typically involved in calcium regulation.
Purpose of the Study:
- To assess bioactivity in patients with malignancies using a cytochemical assay.
- To investigate the role of cyclic adenosine monophosphate (cAMP) as a second messenger.
- To differentiate the source of bioactivity from PTH.
Main Methods:
- A cytochemical bioassay, initially for PTH, was employed.
- Plasma bioactivity, serum calcium, and nephrogenous cAMP excretion were measured.
- Gel chromatography was used to analyze plasma bioactivity components.
Main Results:
- Increased cytochemical bioactivity was observed in hypercalcemic cancer patients with elevated nephrogenous cAMP.
- Mean bioactivity levels were significantly higher in these patients compared to controls.
- Post-tumor resection, one patient normalized bioactivity, serum calcium, and cAMP excretion.
- Gel chromatography indicated the bioactive substance differs from PTH-(1-84).
Conclusions:
- The cytochemical bioassay can detect elevated bioactivity in malignancy-associated hypercalcemia.
- The identified bioactive substance appears distinct from PTH-(1-84).
- This assay serves as a sensitive tool for further research into the pathogenesis of malignancy-associated hypercalcemia.