Severe Thyrotoxicosis Does Not Accelerate 1a-Hydroxylation of 25-Hydroxyvitamin D3 in Dogs. Experimental Study


Two healthy dogs weighing 18 kg and 13 kg each received an intravenous injection of 7 μg/kg 25-hydroxyvitamin D3 (25OHD3). Subsequently, they were blood-sampled in order to determine the plasma levels of 25(OH)D3 over 4-hourly time intervals and for a time period of 24 hours. After a period of 18 days since the last blood sampling, the animals were brought to a hyperthyroid state and the intravenous injection of 7 μg/kg 25OHD3 was repeated. Blood sampling was performed every 4 hours and over a time period of 24 hours in order to determine the levels of 25OHD3. The graphic plotting of plasma levels of 25OHD3 in the euthyroid state did not differ from that in the hyperthyroid state. This finding in dog animal experimentation is indicative that the increased levels of thyroid hormones did not affect the activity of CYP27B1 and CYP24A1 enzymes that are related to the catabolism of 25OHD3 over a minimum of 24 hours period.

Share and Cite:

C. Georgiou Velentzas, "Severe Thyrotoxicosis Does Not Accelerate 1a-Hydroxylation of 25-Hydroxyvitamin D3 in Dogs. Experimental Study," International Journal of Clinical Medicine, Vol. 4 No. 12, 2013, pp. 539-542. doi: 10.4236/ijcm.2013.412093.

Conflicts of Interest

The authors declare no conflicts of interest.


[1] R. Bouillon, E. Muls and P. De Moor, “Influence of Thyroid Function on the Serum Concentration of 1,25 Dihydroxyvitamin D,” Journal of Clinical Endocrinology & Metabolism, Vol. 51, No. 4, 1980, pp. 793-797.
[2] A. Mac Farlane, E. B. Mawer, J. Berry and J. Hann, “Vitamin D Metabolism in Hyperthyroidism,” Clinical Endocrinology, Vol. 17, No. 1, 1982, pp. 51-59.
[3] C. G. Velentzas, “The Hydroxylation of Vitamin D on C25 in Thyrotoxicosis: The Role of the Activity of Microsomal Liver Enzymes,” International Journal of Clinical Medicine, Vol. 3, No. 4, 2012, pp. 295-299.
[4] C. G. Velentzas, “Vitamin D and Thyroid Hormones,” In: S. R. Malone, Ed., Vitamin D Nutrition Side Effects and Supplements, 2009, pp. 175-184.
[5] D. A. Piatnek and R. E. Olson, “Experimental Hyperthyroidism in Dogs and Effect of Salivariectomy,” American Journal of Physiology, Vol. 201, 1961, pp. 723-728.
[6] R. C. De Bodo and M. W. Sinkoff, “The Role of Growth Hormone in Carbohydrate Metabolism,” Annals of the New York Academy of Sciences, Vol. 57, 1953, p. 23.
[7] W. R. Brewster, J. P. Isaacs, P. F. Osgood and Th. L. King, “The Hemodynamic and Metabolic Interrelationships in the Activity of Epinephrine, Norepinephrine and the Thyroid Hormones,” Circulation, Vol. 13, 1956, p. 1.
[8] D. Piatnek-Leunssen and R. E. Olson, “Cardiac Failure in the Dog as a Consequence of Exogenous Hyperthyroidism,” Circulation Research, Vol. 20, 1967, p. 242.
[9] H. M. M. Frey, “Peripheral Circulatory and Metabolic Consequences of Thyrotoxicosis. Blood Flow and Oxy gen Consumption of Resting and Working Skeletal Muscle in Experimental Thyrotoxicosis in the Dog,” Scandinavian Journal of Clinical & Laboratory Investigation, Vol. 19, No. 1, 1967, p. 4.
[10] W. Reece, “Duke’s Physiology of Domestic Animals,” 12th Edition, Cornell University Press, New York, 2004, p. 565.
[11] J. G. Haddad and T. C. B. Stamp, “Circulating 25 Hydroxyvitamin D in Man,” American Journal of Medicine, Vol. 57, No. 1, 1974, pp. 57-62.
[12] O. Makoto Kuro, “Overview of the FGF-23-Klotho Axis,” Pediatric Nephrology, Vol. 25, No. 4, 2010, pp. 583-590.
[13] S. Drake, “Galileo at Work: His Scientific Biography,” Mineola (NY) Dover, 2003.
[14] D. E. Prosser and J. Glenville, “Enzymes Involved in the Activation and Inactivation of Vitamin D,” Trends in Biochemical Sciences, Vol. 29, No. 12, 2004, pp. 664-673.
[15] G. A. Brent, R. Larsen and T. F. Davies, “Hypothyroidism and Thyroiditis,” In Williams Textbook of Endocrinology, 11th Edition, 2008, p. 382.

Copyright © 2024 by authors and Scientific Research Publishing Inc.

Creative Commons License

This work and the related PDF file are licensed under a Creative Commons Attribution 4.0 International License.