The effect of alendronate on renal tubular reabsorption of phosphate.
We report the effects of alendronate on phosphate homeostasis in two patients. In a woman with postmenopausal osteoporosis, the infusion of alendronate (7.5 mg intravenously daily for 4 consecutive days) was not associated with secondary hyperparathyroidism despite a reduction in serum calcium. This was associated with a rise in serum phosphate and TmP/GFR. This response contrasted with those observed in 14 other patients with osteoporosis, in whom PTH rose significantly following the infusion of alendronate in association with a significant fall in serum phosphate and TmP/GFR. The second patient, a woman with Paget's disease, was treated with intravenous alendronate (10 mg daily for 5 consecutive days) on two occasions for relapse of disease activity. On the first occasion there was a 150% rise in serum PTH associated with a fall in serum phosphate and TmP/GFR. On the second occasion, when the rise in serum PTH was less marked, there was a rise in serum phosphate and TmP/GFR. We conclude that alendronate may increase renal tubular reabsorption of phosphate, but that this effect is usually offset by secondary hyperparathyroidism.
Vasikaran
S D
SD
WHO Collaborating Centre for Metabolic Bone Disease, University of Sheffield Medical School, UK.
O'Doherty
D P
DP
McCloskey
E V
EV
Gertz
B
B
Kahn
S
S
Kanis
J A
JA
D000042:Absorption / Q000187:drug effects; D000368:Aged; D019386:Alendronate; D002118:Calcium / Q000097:blood; D004164:Diphosphonates / Q000008:administration & dosage / Q000494:pharmacology* / Q000627:therapeutic use; D005260:Female; D005919:Glomerular Filtration Rate / Q000187:drug effects; D006706:Homeostasis / Q000187:drug effects; D006801:Humans; D006962:Hyperparathyroidism, Secondary / Q000097:blood / Q000209:etiology; D007275:Injections, Intravenous; D007684:Kidney Tubules / Q000187:drug effects* / Q000378:metabolism; D010001:Osteitis Deformans / Q000097:blood / Q000188:drug therapy* / Q000378:metabolism; D015663:Osteoporosis, Postmenopausal / Q000097:blood / Q000188:drug therapy* / Q000378:metabolism; D010281:Parathyroid Hormone / Q000097:blood; D010710:Phosphates / Q000097:blood / Q000378:metabolism*
D004164:Diphosphonates; D010281:Parathyroid Hormone; D010710:Phosphates; D002118:Calcium; D019386:Alendronate