Dietary sevelamer hydrochloride prevents dietary 1 alpha‐hydroxycholecalciferol (1 alpha‐OH D3)‐induced increases in plasma phosphorus

Abstract

A study on the mechanism by which sevelamer hydrochloride (Sev), a polymeric phosphate binder, lowers plasma phosphorus in end‐stage renal failure patients was conducted using a day‐old chick model. Three pens of 5 broiler‐type male chicks/treatment were fed a diet marginally deficient in phosphorus (diet 1, P deficient), diet 1 plus adequate inorganic phosphorus (diet 2), diet 1 plus 20ug/Kg 1 alpha‐OH D3 (diet 3), diet 2 plus 2 g/Kg diet Sev, or diet 3 plus 2g/Kg diet Sev. After three weeks, all chicks were weighed, bled (to determine plasma phosphorus), and the right tibiotarsus was collected for determination of dry fat‐free bone ash. Addition of phosphorus or 1 alpha‐OH D3 to the P deficient diet (diet 1) increased weight, bone ash, and plasma phosphorus as compared to chicks fed a phosphorus deficient diet (p<0.001). Addition of Sev was ineffective at reducing body weight, plasma phosphorus or bone ash when phosphorus was made adequate using inorganic phosphorous, but did decrease these variables when added to the diet supplemented with 1 alpha‐OH D3 (p<0.001). These data showed that Sev, at the dose used, was not able to counteract improved phosphorus status associated with inorganic phosphorus supplementation but was effective in preventing improved phosphorus status resulting from the addition of 1 alpha‐OH D3. This work was supported by the Wisconsin Alumni Research Foundation.