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A great deal of useful information about calcium metabolism in man has been obtained by balance technics. Balance studies give only net changes in total body calcium and do not indicate whether changes in balance result from alterations of rates of movement into or out of bone. For example, positive balance could result from increased bone deposition or decreased bone resorption. Similarly, balance could be unchanged if increased resorption were matched by increased deposition. Rates of bone deposition have been measured in man using Ca45 and Ca47 as tracers (1-1 1). Isotopes of strontium have been similarly used (5,6,8,(11)(12)(13)(14)(15)(16), since strontium is a boneseeking element whose distribution in the body is similar to that of calcium. Accumulated experience suggests that cautious use of these boneseeking radionuclides in human subjects is without demonstrable risk. Nevertheless, this experience is still limited both in numbers of subjects and length of observation. In a study of Sr90 toxicity in mice, a direct linear relationship was noted between total internal radiation dose from Sr90 and decrease in survival time and tumor production (17 individual under varied conditions. This possibility is the subject of the present investigation. The results indicate that nonradioactive strontium can be used to detect alterations of skeletal metabolism in various defined physiological and pathological states. METHODSThe following subj ects were studied: 25 healthy persons at ordinary activity (including 11 inmates of San Quentin Prison; 31 studies) 14 athletes (all members of the San Quentin Prison football team) ; 11 patients with idiopathic nephrolithiasis; 28 with primary hyperparathyroidism (4 with skeletal disease shown by elevated serum alkaline phosphatase levels or roentgenographic evidence of skeletal involvement or both; 17 with normal phosphatase and X-ray appearance but with microscopic foci of resorption seen in bone biopsy; and 7 with normal phosphatase, X-ray appearance and bone biopsy); 7 with hyperthyroidism; 8 with acromegaly; 3 with hyperadrenocorticism; 26 with advanced, unequivocal postmenopausal or senile osteoporosis (40 studies); 5 with Paget's disease of bone; and 1 with chronic vitamin D overdose. The reproducibility of the method was tested by 21 duplicate tests in osteoporotic and normal subjects. All subjects were on diets free of milk and cheese except the prisoners, whose fare was unrestricted. All subjects were ambulatory.Significant dietary strontium was excluded by checking initial blood and urine specimens. Then 10.0 mEq of strontium gluconate' was infused intravenously over a period of 10 minutes. Blood samples were taken every 24 hours and 24-hour urine specimens were collected for 4 to 6 days.All specimens were collected in acid-washed glassware. All determinations were done in duplicate. Serum and urine calcium levels were determined on a flame spectrophotometer by the method of Maclntyre (18). Serum strontium was measured by diluting 1.0 ml of serum with 3 ml of an aqueo...

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Aluminum-containing drugs are used extensively to bind dietary phosphate and as antacids, but little is known about toxicity and tissue uptake of ingested aluminum. Aluminum concentrations were measured by neutron activation analysis in tissues taken from hyperparathyroid and normal human subjects and from rats. The parathyroid glands contained significantly more aluminum per unit mass than did thyroid or cervical muscle. The concentration of aluminum in the parathyroids appears to be linearly related to dietary aluminum intake.

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Eleven of twelve human breast cancers contained a lipid which increased urinary (45)Ca and (40)Ca excretion of (45)Ca-labeled, parathyroidectomized rats receiving a low Ca diet. The lipid has mobility on thin-layer chromatography and gas-liquid chromatography close to, but not identical with, that of 7-dehydrocholesterol. Authentic 7-dehydrocholesterol has osteolytic activity similar to that of the extracted sterol. Fluorescence and Lieberman-Burchard reactions of the extracted sterol are similar to those of 7-dehydrocholesterol. The lipid was found by thin-layer chromatography in the extracts which had osteolytic activity. Neither the lipid nor osteolytic activity was found in extracts of tissue from two normal human breasts.

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