Following a four-day control period during which an elevated serum
calcium level either stabilized or continued to rise despite maximally tolerated saline diuresis, 12 patients with neoplastic
hypercalcemia were treated with intravenous
etidronate disodium (
etidronate) 7.5 mg/kg/day for up to seven days. Serum
calcium reverted to normal levels in all patients, with the mean pretreatment serum
calcium level of 12.5 +/- 0.4 mg/dl dropping to 9.2 +/- 0.2 mg/dl (p less than 0.01) by Day 7. Elevated urinary
calcium (1,107 +/- 134 mg/g
creatinine) and
hydroxyproline levels (154 +/- 16 mg/g
creatinine) declined to 245 +/- 52 mg/g
creatinine and 75 +/- 14 mg/g
creatinine, respectively, suggesting a marked reduction in
bone resorption following treatment. Serum
phosphorus levels were unchanged, but urinary
phosphorus levels dropped rapidly from 1,181 +/- 125 mg/g
creatinine before treatment to 723 +/- 94 mg/g
creatinine after two days. Serum
parathyroid hormone levels (mid-molecule assay) were suppressed before treatment (64 +/- 16 pg/ml), but rose rapidly to 223 +/- 68 pg/ml by Day 7 of treatment. The value of serum
1,25-dihydroxyvitamin D was initially below normal (16 +/- 3 pg/ml), but rose rapidly with treatment to 42 +/- 12 pg/ml by Day 7. Symptoms of
hypercalcemia and bone
pain improved with treatment, and no serious adverse reactions to treatment were encountered. Intravenous
etidronate is apparently an effective and safe treatment for neoplastic
hypercalcemia.