Hypercalcemia and hyperosteolysis in vitamin D intoxication: effects of clodronate therapy.
Vitamin D intoxication is a rare cause of hypercalcemia, which is associated with severe and prolonged morbidity. Hypercalcemia and/or hypercalciuria are the consequence of increases in both intestinal absorption and bone resorption. We report on 7 cases of vitamin D overdose (25-hydroxyvitamin D: 710 +/- 179 nmol/l; normal range: 20-90). The indications for vitamin therapy were osteoporosis (5), hypoparathyroidism (1), and osteomalacia (1). Enhanced bone resorption was demonstrated by increased fasting urinary calcium excretion (0.192 +/- 0.067 mmol/l GFR, normal < 0.045). Sequential biochemical measurements in the hypoparathyroid patient showed the persistence of abnormally elevated fasting urinary calcium and of serum 25-hydroxyvitamin D concentrations, even after normalization of plasma calcium, emphasizing that enhanced bone resorption is a prominent feature of vitamin D action. The intravenous administration of a single infusion of the bisphosphonate clodronate to 3 patients led to a correction of hypercalcemia/hypercalciuria, whereas prednisone therapy given to 2 other cases barely affected the abnormal biochemical values. These results indicate that enhanced bone resorption encountered in vitamin D intoxication could be favorably influenced by bisphosphonate treatment.
Rizzoli
R
R
Department of Medicine, University Hospital, Geneva, Switzerland.
Stoermann
C
C
Ammann
P
P
Bonjour
J P
JP
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002118:Calcium / Q000652:urine; D004002:Clodronic Acid / Q000627:therapeutic use*; D062787:Drug Overdose / Q000150:complications; D005260:Female; D006801:Humans; D006934:Hypercalcemia / Q000139:chemically induced / Q000188:drug therapy* / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D010014:Osteolysis / Q000139:chemically induced / Q000188:drug therapy* / Q000503:physiopathology; D014807:Vitamin D / Q000506:poisoning*
D004002:Clodronic Acid; D014807:Vitamin D; D002118:Calcium