Strontium and Calcium Metabolism in Metabolic Bone Diseases *

Abstract

Skeletal and systemic disease may be reflected in profound alterations of the metabolism of the bone salts. In human skeletal disease attention has focused, for the most part, on the altered metabolism of calcium. Several studies indicate that strontium may have a metabolic pathway similar to that of calcium and that radiostrontium, because of its ease of measurement, might be a convenient indicator for observing the transfer of calcium through the calcium-containing compartments of the body.The investigations to be reported here are concerned with the comparative distribution and fate of calcium and strontium in subjects with altered bone metabolism. Patients with thyroid and parathyroid disease, osteoporosis, and Paget's disease were studied after simultaneous intravenous administration of strontium85 and calcium45. The results indicate that Sr85 closely parallels Ca45 as an index of skeletal function. MATERIALS AND METHODSAll patients (Table I) were on the Metabolic Research Ward, were ambulatory throughout the study, and spent a few hours out of doors each day with a nurse in attendance. Each received a constant neutral ash diet containing 88 to 206 mg of calcium per day (Table II). The calculated daily magnesium intake did not exceed 200 mg. Fluid intake was kept between 2,000 and 2,500 ml per day. After a minimum of 7 days on the fixed diet, a 3-day control collection of urine and feces was obtained before administration of the labeled isotopes.The dose of labeled calcium and strontium was prepared from hydrochloric acid stock solutions of Ca"C121 of high specific activity, and from carrier-free Sr5'Cl,.

Quantitation of Calcium Metabolism. Theory*

“…Equation 5 applies as well, but absorption is also defined by Va = Vi + Vd -VF, [9] and the fraction absorbed becomes a = Va/ (Vi + Vd). [10] Equations 8, 9, and 10 are based on the assumption that vi and Vd are absorbed to the same extent and therefore presumably are thoroughly mixed (1).…”

Strontium and Its Relation to Calcium Metabolism*

“…[13] In a system without central pool of constant size, this specific activity remains constant throughout the experiment. By combining Equations 12 and 13, one obtains the amount of radioactivity, R, circulating at time t: R = Ri MOe-(ku+kf+ko+)t = Rie-(ku+kf+ko+)t [14] If RB is the amount of circulating radioactivity per unit of plasma volume, the time-course of this parameter can be expressed in terms of Equation 14 as follows: [15] where L = total apparent volume of distribution of the circulating mass ( [18] 1098 E10] 2 If the experimental error is 5%, the absolute error for the mean urine excretion of Ca45 (Table III) is 0.80 (0.05 X 16) and for fecal excretion of Ca450.70 (0.05 X 14). The error for the total excretion is therefore 1.5, which necessarily is the same absolute error for the percentage of dose in bone [100 -(14 + 16)].…”

“…Early experiments (1)(2)(3) confirmed this notion in a general way, and several investigators (4)(5)(6)(7) have subsequently proceeded on the assumption that Sr behaves like Ca in the body. Although the urinary excretions of Sr and Ca were found to differ, it has been assumed or demonstrated that as far as the skeleton is concerned, differences in the biological behavior of Ca and Sr are small and perhaps negligible (4,(8)(9)(10)(11)(12)(13)(14)(15).…”

Calcium Metabolism of the Normal Rhesus Monkey*

“…This lower uptake may be a reflection of the emotional stress observed in these monkeys during intubation, and which Malm (26) considered to be a factor in human subjects. 4. Urine: feces ratios of Ca45 excretion.…”

“…Data obtained on patients with carcinoma, multiple myeloma, and thyroid disorders indicate that the excretion of Ca45 is disturbed in these situations, for the urine: feces excretion *A portion of this paper was presented at the Fifth International Congress on Nutrition, Washington, D. C., September 1, 1960. This study was ratios ranged between 3:1 and 1: 3 (3)(4)(5)(6). In spite of these anomalies, the "endogenous" excretion of calcium by normal human beings and normal monkeys appears to be similar, and quite unlike that by the dog and the rat.…”