Because sevelamer is not orally absorbed, sevelamer does not reach the breastmilk or adversely affect the breastfed infant after maternal administration. A suspension of sevelamer has been added directly to breastmilk to lower the phosphorus concentration of milk. This could be a useful maneuver for breastmilk use in infants with renal impairment; however, clinical use has not been reported. In addition to lowering average phosphorus content by 65% to over 80%, the calcium content of breastmilk was reduced by almost as much and the casein content also decreased somewhat. With sevelamer hydrochloride, the chloride content increased by 60% and the pH changed from 6.8 to 7.8, although pH appears to rebound over time.[1,2] Addition of large amounts of sevelamer to artificial formula also lowers the copper, magnesium, manganese, potassium, sulfur and zinc concentrations by about 20%.[3] Similar reductions might occur with breastmilk.