72. J. Jowsey: Bone Formation and Resorption in Bone Disorders 



Hyperthyroidism 



Osteoporosis or decreased density of the skeleton on x-ray is frequently associated 

 with hyperthyroidism. The five cases reported here show an increase in the level of 

 the resorption of bone in all but one case, and two of the five also demonstrate an 

 increase in the level of bone formation. The values are similar to those seen in osteo- 

 porotic bone but the levels of formation appear to be higher. 



Paget's disease 



Facet's disease differs from other conditions discussed in this report in that it is a 

 localised lesion and is not considered as a metabolic abnormality. The x-ray changes 

 seen in this disease are dramatic and are characterised by an increase in the volume 

 of localised areas of bone accompanied by a decrease in the density. Histology 

 demonstrates many cement lines associated with a great deal of formation and 

 resorption of bone. Quantitative microradiography has not really added much to our 

 knowledge; the study of fourteen specimens show the very high levels of both 

 resorption and formation that are to be predicted from the histological picture. 



Summary and conclusions 



Decreased skeletal density is a frequently found radiological appearance in most 

 bone disorders and can be explained, in terms of turnover measurements, by an in- 

 creased resorption of bone (Fig. 1). Bone formation levels are increased in a per- 

 centage of subjects suffering from hyperparathyroidism and hyperthyroidism and in all 

 cases of Faget's disease, decreased levels being found in hypoparathyroidism and 

 hypercortisonism. It is of particular significance that bed-rest also results in a decrease 

 in bone formation usually within a relatively short time. 



The introduction of quantitative microradiography has provided a measure of 

 bone turnover, which can explain radiological changes and further characterise the 

 various bone disorders. 



Acknowledgemeyits 



A large part of this study has depended on collection of normal material from 

 different institutions, in particular the city morgues in Fhiladelphia and Minneapolis; 

 pathological material was provided by Dr. L. Lutwak of the National Institutes of 

 Health, Dr. S. Lewis from Philadelphia and from the Mayo Clinic. I would like to 

 thank these people for the time and effort they spent in collecting the material 

 without which the study would obviously have been impossible. 



References 



Heaney, R. p.: Radiocalcium metabolism in disuse osteoporosis in man. Amer. J. Med. 33, 

 188 (1962). 



JowsEY, J.: Age changes in human bone. Clin. Orthop. 17, 210 (1960). 



— , P. J. Kelly, B. L. Riggs, A. J. Bianco, D. A. Scholz, and J. Gershon-Cohen: Quan- 

 titative microradiographic studies of normal and osteoporotic bone. J. Bone Jt Surg. 47-A, 

 785; 872 (1965). 



