[Effect of 1,25-dioxycholecalciferol and 24,25-dioxycholecalciferol on calcium homeostasis in rats given hydrocortisone in the diet with various phosphorus contents].

High content of phosphorus in the diet (1.8% of phosphorus in the diet, Ca:P ratio 1:3) accelerated the development of hypocalcemia and osteoporosis and increased their degree in rats which received hydrocortisone (3.5 mg/10 g bw a day for 4 weeks). Reduction of phosphorus consumption to 0.3% (Ca:P ration 1:0.5) essentially retarded the development of these disturbances and lowered their degree. The use of 1,25-dioxycholecalciferol and 24,25-dioxycholecalciferol in doses of 0.03 and 1.5 mg, respectively promoted the normalization of phosphorus-calcium metabolism and improvement of the status of the osseous tissue in rats given hydrocortisone coupled with both diets. The most beneficial affect on calcium homeostasis in exogenous hypercorticoidism was attained with the use of active metabolites of vitamin D3 coupled with the diet with a low phosphorus content (0.3%). In this case there was a complete normalization of the density of the osseous tissue and of the calcium and phosphorus content. In view of this fact it is advisable to combine active metabolites of vitamin D3 and the diet with a low phosphorus content.