Strontium Inhibition of Vitamin D3-Induced Calcium-Binding Protein (CaBP) and Calcium Absorption in Chick Intestine

Immune System Modifications Induced in a Mouse Model of Chronic Exposure to90Sr

“…Strontium ingestion reduced the duodenal activation of vitamin D 3 (conversion of 25-hydroxycholecalciferol to 1,25-dihydroxy cholecalciferol), reduced the activity of calcium binding protein, and reduced the absorption of calcium by the duodenum. Similar effects were observed in chickens given excess strontium in a diet with adequate vitamin D, but deficient in calcium (0.01%) (Corradino and Wasserman 1970;Corradino et al 1971aCorradino et al , 1971b. In addition, excess strontium ingestion significantly reduced the absorption of glucose, histidine, and alanine by the duodenum to levels typical of rachitic (vitamin D-deprived) chickens (Corradino et al 1971b).…”

Strontium and Bone

“…(74) All together, one can conclude that high doses of strontium may indirectly affect bone metabolism by reducing the intestinal absorption of calcium, decreasing the concentration of the duodenal Ca-BP, and inhibiting the conversion of 25(OH)D 3 to 1,25(OH) 2 D 3 . (10,(42)(43)(44) …”

“…(79) Later on this was attributed to the element's ability to inhibit the in vivo biosynthesis of the active 1,25(OH) 2 D 3 metabolite. (9,10,42,43) We have just finished a worldwide multicenter study in the frame of which serum strontium levels were found to be inversely correlated with renal function. Moreover, in patients treated by hemodialysis, serum strontium levels greatly differed from center to center and country to coun- (38,39) 1.…”

“…No changes in vitamin D levels (38) 7. Decreased vitamin D levels, due to inhibition of vitamin D synthesis (9,10,42,43) try (range 29.0 ± 11.0 g/l up to 466 ± 90 g/l). In the latter population, statistical analysis revealed that increased serum strontium levels (> 100 g/l) could for 48% be explained by the use of strontium-contaminated dialysis fluids, whereas the diet, medication, and dialysis modalities appeared to play only a minor role.…”

“…However, caution was warranted with these preventive measures since replacement of dietary calcium with strontium was found to result in diminished growth, improper bone mineralization, and an inhibition of intestinal calcium absorption. (9,10) …”