430 URIST, MACDONALD, MOSS, AND SKOOG 



Teng et al. (1961<7, 1961/;) described osteoporosis in 7 children 

 with a systemic disorder of protein metaboHsm caused by tumors, 

 cirrhosis, and von Gierke's disease. As in patients with senile osteo- 

 porosis, the urinary excretion of calcium was decreased, owing to 

 the low rate of turnover of bone tissue. Apparently skin, muscle, 

 and bone had a low priority rating and were deprived of their supply 

 of proteins to fulfill the needs of organs of vital bodily functions. A 

 60-year-old osteoporotic woman, who had only 50 per cent of the 

 normal bone mass, was calculated to have had a 10 per cent deficit 

 in bodv protein. Adrenal 11-oxy corticosteroids decreased the rate 

 of protein svnthesis, or increased the rate of protein breakdown. 

 Hence, metabolic reactions, nutritional factors, and hormonal influ- 

 ences were interdependent, and the rate of differentiation of oste- 

 oblasts and deposition of bone must have been regulated by each 

 and all. 



Skeletal Kinetics 



The recent literature on measurement of turnover of bone tissue 

 by tracer techniques with radioisotopes, stable strontium, and tetra- 

 cycline has alreadv been reviewed in detail (Bauer et al., 1961; 

 Eisenberg and Gordan, 1961; Urist, 1962; Urist et al, 1962). When 

 the results of two or three tracer technics were correlated with the 

 results of conventional chemical balance studies and bone biopsy, 

 we concluded that the use of tracer dilution formulas measured the 

 activity of less than 1 per cent of the total bone tissue (Urist et al., 

 1962) and gave no information about the volume of the total bone 

 mass. Less than 1 per cent of the skeleton was capable of turning 

 over 0.5 to 1.0 gm of calcium, the daily rec|uirement of an adult 

 human being. Therefore, the defect in osteoporosis was in the proc- 

 ess of storage of calcium in structural bone, not in the activity of 

 reactive or metabolic bone. Nevertheless, Eisenberg and Gordan 

 ( 1961 ) identified two divergent groups in 26 patients with osteo- 

 porosis. One group had small miscible pools and low bone formation 

 rates, as, for example, osteoporotics of advanced age or with Cush- 

 ing's SMidrome. Another group had large miscible pools and rapid 

 bone formation rates, as, for example, in thyrotoxicosis and acro- 

 megaly, in which there is excessive bone resorption. Thus, in cases of 



