Tumor-induced hypercalcemia in a patient with extensive soft tissue sarcoma: effects of bisphosphonate therapy and surgery

Hypercalcemia of Malignancy: Simultaneous Elevation in Parathyroid Hormone-Related Peptide and 1,25 Dihydroxyvitamin D in Sarcoma

Objective

Hypercalcemia is a common finding in patients who have an underlying malignancy. Only a few cases of hypercalcemia of malignancy have been linked to more than one mechanism of hypercalcemia. Here, we present a patient with liposarcoma and hypercalcemia of malignancy in the setting of simultaneous elevations in parathyroid hormone-related peptide (PTHrP) and 1,25 dihydroxyvitamin D [1,25(OH)₂D] levels. Sarcoma-associated hypercalcemia is a rare disorder.

Methods

The patient was an 89-year-old woman with sarcoma-associated hypercalcemia. Multiple mechanisms were uncovered, and treatments were adjusted for them. Literature search for hypercalcemia of malignancy with multiple mechanisms was conducted.

Results

This is the first report describing dual mechanisms of sarcoma-associated hypercalcemia and only the fifth report on PTHrP and 1,25(OH)₂D simultaneously causing hypercalcemia of malignancy.

Conclusion

Based on this finding, we recommend measuring the 1,25(OH)₂D levels in conjunction with the PTHrP level in patients with malignancy as this would allow for a more proactive approach to the diagnosis and treatment of hypercalcemia of malignancy.

Levels of C-telopeptide fragments of collagen type I enable the monitoring and early adjustment of clodronate therapy in patients with postmenopausal osteoporosis

We monitored the efficacy of therapy with clodronate, a bisphosphonate drug, in women with postmenopausal osteoporosis, using urinary immunoenzymatic assay of C-telopeptide of collagen type I, an eight amino acid fragment (collagen fragment) of the C-telopeptide of the alpha1-chain of collagen type I (EKAHDGGR). The analysis of the dynamics of collagen fragment concentrations (a marker of bone resorption) during treatment suggests the possibility of early modulation and customization of therapy based on the levels of this marker. This could enable improved control over secondary effects and side effects of clodronate therapy. Pharmacologic inhibition of bone resorption by osteoclasts could be indirectly responsible for the increase in parathyroid hormone found during treatment with clodronate. Increased levels of parathyroid hormone are probably necessary to stimulate residual osteoclast activity and are sufficient for the maintenance of calcium-phosphate homeostasis in a new pharmacologically-induced equilibrium. Outside this context the levels of parathyroid hormone of certain patients would be considered pathologic.