Histological and biophysical studies of bone tissue in primary vitamin-D resistant rickets have shown structural features that in this disease differ from those found in ordinary human rickets. Compact bone has been found to show structural chagnes resembling those found in Paget's disease. These changes are characterized by an abnormal mosaiclike pattern of bone tissue which is not affected by large doses of vitamin D. Histological examination of the costochondral junction of these patients, however, reveal abnormalities similar to those found in ordinary vitamin-D deficiency rickets.
It may be concluded that vitamin-D resistant rickets is a well defined, genetically determined clinical and pathological entity, different from ordinary rickets. Treatment with vitamin D in massive doses has no direct effect upon the skeleton in vitamin-D resistant rickets. Vitamin D improves the possibilities for a deposition of mineral salts in the skeleton by its hypercalcemic effect, but does not influence the morphology of the skeletal disorder and does not cure the disease.