Breast cancer-associated hypercalcaemia: a reassessment of renal calcium and phosphate handling.
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.
Gallacher
S J
SJ
University Department of Medicine, Glasgow Royal Infirmary, UK.
Fraser
W D
WD
Patel
U
U
Logue
F C
FC
Soukop
M
M
Boyle
I T
IT
Ralston
S H
SH
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
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