SKELETAL DYNAMICS IN MAN MEASURED BY NONRADIOACTIVE STRONTIUM*

Abstract

Skeletal dynamics were calculated by usual dilution formulas using stable strontium as tracer in 25 normals, 14 athletes, 26 patients with postmenopausal osteoporosis, 28 with primary hyper-parathyroidism, 3 with Cushing''s disease, 9 with acromegaly, 7 with thyrotoxicosis, 11 with recurrent kidney stones, 5 with Paget''s disease of bone and 1 with chronic vitamin D poisoning. The technique requires that 10 meq. of strontium gluconate be injected intravenously and blood and urine concentrations be measured for 4 to 6 days. Normal subjects had miscible pools of 42. 7 of which 3. 9 L per 24 hrs. was excreted by the kidney and 9. 6 L per 24 hrs. went to bone. Fecal excretion which accounted for only 2. 5% of the pool was not measured routinely. Exercise expanded the pool and accelerated bone deposition rate. Two types of osteoporosis were found: a small pool and low rate of bone deposition were found in postmenopausal osteoporosis and Cushings disease of long duration. The large pool and rapid rate of bone disposition in thyrotoxicosis was confirmed and also found in acromegaly. Urinary excretion rate was excessive in Cushing''s disease, thyrotoxicosis, and acromegaly. In hyperparathyroidism with clinically evident osteitis, expanded pools, greatly increased turnover, urinary excretion, and bone deposition rates were confirmed. In addition, patients who had normal roentgen appearance and phosphatase were shown to have bone involvement by slight increase in bone deposition rate and microscopic foci of resorption on iliac crest biopsy. In 7 patients without histologic foci of resorption the bone deposition rate was not increased.