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.
WHO Collaborating Centre for Metabolic Bone Disease, University of Sheffield Medical School, UK.
S D
SD
Vasikaran
D P
DP
O'Doherty
E V
EV
McCloskey
B
B
Gertz
S
S
Kahn
J A
JA
Kanis
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