Nephrology Department Misericordia e Dolce Hospital Prato Italy Email: mamato{at}usl4.toscana.it
Sir,
We read with great interest the recently published article by Malluche and Mawad [1] reviewing the challenging issue of phosphate control in chronic nephropaties. Usually, to ensure an adequate caloric intake, most patients with end-stage renal disease (ESRD) are in positive phosphorus balance. Thus, control of blood phosphate concentrations has become a must in treating ESRD patients, but few issues have been as arguable as phosphate binder use. Aluminium-based binders were found to cause bone and brain disorders while calcium-based binders were blamed for metastatic calcification and adynamic bone disease. The query for the identification of a safe and effective phosphate binder has been acknowledged in sevelamer hydrochloride, which has been welcome as an ideal binder. The ability of sevelamer to control serum phosphorus is unquestionable, but we would raise the question of its tolerability. The authors describe a low incidence of side effects associated with the use of sevelamer. In our experience, most haemodialysis patients complained of various gastrointestinal discomforts with sevelamer doses ranging from 1.2 to 2.0 g/day, far below the mean daily dose of 5.4 g/day reported to control blood phosphorus [2], and we were induced to stop therapy when increasing the drug dose in many instances. In the same study [2], 10.4% of the enrolled patients were reported to have discontinued treatment due to an adverse event, not a negligible value at all. We, and our patients too, believe that sevelamer side effects do not satisfy the requirements of an ideal therapy. We reckon that it is a valuable add in the treatment of renal bone disease allowing lower doses of calcium-based phosphorus binders and decreasing the risk of hypercalcaemia. However, in our opinion the search for the safe, effective and ideal phosphate binder is still open, at least for the time being.
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