HYPEUVITAMINOSLS D G81 



Harris"^ considers that 5,000 I.U./kg. body weight is a safe daily dose. 

 He found that vitamin D injected intramuscularly caused no injury, 

 whereas the same dose given orally induced symptoms of toxicity. Al- 

 bright and Reifenstein^^^ are of the opinion that all manifestations of 

 hypervitaminosis are merely an exaggeration of the normal action of the 

 vitamin. 



In the case of rats on a good calcium and phosphorus diet, Guldager"^ 

 observed that vitamin D toxicity occurred when the dosage was in the 

 range of 300 to 700 I.U. daily. When the maximum dosage of 700 I.U. 

 was given, calcium deposits were found in the kidneys, without exception. 

 Some differences in the toxicity of vitamin D2 (activated ergosterol) and 

 natural vitamin D (vitamin Ds-activated 7-dehydrocholesterol) were 

 reported by Morgan et a/.^"^-"^ in rats, and by McChesney and Kocher,"^ 

 also in rats. Morgan et al. "* found that both the absorption and the ex- 

 cretion of vitamin D3 by rats were more efficient than was the case with 

 vitamin D2. Vitamin D3 appeared to produce more prolonged hyper- 

 calcemia than did vitamin D^."^ However, Nicolaysen and Eeg-Jansen^ 

 conclude that little difference in toxicity can be demonstrated between the 

 several types of vitamins D. Animals and man frequently recover from 

 toxic doses of the vitamins D, but if the dosage is sufficiently high, death 

 ensues. 



"3 p. L. Harris, Aim. Rev. Biochem., 18, .391-434 (1949). 



"* E. Albright and E. C. Reifenstein, Parathyroid Gland and Metabolic Bone Disease, 

 Williams & Wilkins, Baltimore, 1948, p. 95. 



375 A. F. Morgan, N. Shimotori, and J. B. Hendricks, /. Biol. Chem., 134, 761-779 

 (1940). 



"6 E. W. McChesney and H. Kocher, Proc. Soc. Exptl. Biol. Med., 47, 156-159 (1941). 



