Abstract: A pharmaceutical product is disclosed which contains at least a calcium salt or a calcium mixed salt of a natural or chemically modified polymeric, anionic carboxylic acid and/or an ester of sulfuric acid, and additive materials and/or an ester of sulfuric acid, and additive materials and/or carrier materials. There are further disclosed calcium salts, and methods of preparation thereof, comprised of polymannuronic acid, polygalacturonic acid, polyglucuronic acid, polyguluronic acid, the oxidation products of homoglycans, the oxidation products of heteroglycans, or their mixtures, for controlling the levels of phosphate, calcium and iron in patients with chronic uraemia and/or the control of the oxalate and/or phosphate of the blood in kidney stone prophylaxis.