title: Breast cancer-associated hypercalcaemia: a reassessment of renal calcium and phosphate handling.
abstract: The mechanisms of hypercalcaemia were assessed in 20 hypercalcaemic patients with breast cancer. Abnormalities suggestive of a PTH-related peptide (PTHrP) mechanism were observed in up to 60% of cases; urinary cyclic adenosine monophosphate (UcAMP) was elevated in nine patients (45%), renal tubular reabsorption of calcium (RTRCa) was elevated in nine (45%) and the renal tubular threshold for phosphate reabsorption (TmPO4) depressed in 12 (60%). While TmPO4 was lower in patients with high UcAMP, there was no consistent relationship between RTRCa and UcAMP or UcAMP and the extent of bone metastases. In a control group of nine normocalcaemic breast cancer patients, bone resorption as assessed by urinary calcium/creatinine ratio was slightly increased but UcAMP, RTRCa and TmPO4 were generally normal. These observations indicate that a PTHrP-mediated mechanism of hypercalcaemia may be operative in up to 60% of patients with breast cancer, irrespective of the presence or extent of bone metastases.
authors.affiliation: University Department of Medicine, Glasgow Royal Infirmary, UK.
authors.forename: S J
authors.initials: SJ
authors.lastname: Gallacher
authors.forename: W D
authors.initials: WD
authors.lastname: Fraser
authors.forename: U
authors.initials: U
authors.lastname: Patel
authors.forename: F C
authors.initials: FC
authors.lastname: Logue
authors.forename: M
authors.initials: M
authors.lastname: Soukop
authors.forename: I T
authors.initials: IT
authors.lastname: Boyle
authors.forename: S H
authors.initials: SH
authors.lastname: Ralston
mesh_terms: D015415:Biomarkers; D001943:Breast Neoplasms / Q000150:complications* / Q000378:metabolism; D002118:Calcium / Q000097:blood / Q000652:urine*; D003401:Creatine / Q000097:blood / Q000652:urine; D000242:Cyclic AMP / Q000096:biosynthesis*; D006801:Humans; D006934:Hypercalcemia / Q000150:complications* / Q000378:metabolism; D007684:Kidney Tubules / Q000378:metabolism*; D010281:Parathyroid Hormone / Q000097:blood / Q000652:urine; D044162:Parathyroid Hormone-Related Protein; D010446:Peptide Fragments / Q000097:blood / Q000652:urine; D010710:Phosphates / Q000097:blood / Q000652:urine*; D011506:Proteins
chemical_list: D015415:Biomarkers; D010281:Parathyroid Hormone; D044162:Parathyroid Hormone-Related Protein; D010446:Peptide Fragments; D010710:Phosphates; D011506:Proteins; C054296:parathyroid hormone-related protein (1-34); D000242:Cyclic AMP; D003401:Creatine; D002118:Calcium