Dietitian intervention may improve patients’ ability to restrict their daily intake of phosphorus.
Impaired bone mineral metabolism is prevalent in CKD patients, presenting a special challenge for patients and renal health professionals. By stage 5 CKD, an estimated 50% or more of dialysis patients have bone mineral parameters that exceed evidence-based practice guidelines.
Newer pharmacologic treatments combined with dietary interventions show promise in normalizing serum phosphorus, calcium, and intact parathyroid hormone (iPTH) levels, with a goal of improving patient outcomes. Hyperphosphatemia and resulting secondary hyperparathyroidism (SHPT), which are common in hemodialysis patients (Block et al, J Am Soc Nephrol. 2004;15:2208-2218), are major contributors to CVD and all-cause mortality in CKD (Melamed et al, Kidney Int. 2006;70:351-357).
To assist renal health professionals in improving patient outcomes, the National Kidney Foundation (NKF) Kidney Disease Outcomes Quality Initiatives (K/DOQI) developed evidence-based recommendations, “K/DOQI clinical practice guidelines for bone metabolism and disease in chronic kidney disease” (Am J Kidney Dis. 2003;42:S1-S201).
Regarding the importance of diet, K/DOQI clinical practice guidelines acknowledge that “it is critical to provide consistent and regular follow-up during prescription of dietary phosphate restriction while ensuring adequate protein intake.” Recommendations advise limiting phosphorus to 800-1,000 mg daily for serum levels greater than 5.5 mg/dL in stage 5 CKD or if above 4.6 mg/dL in earlier CKD stages, and for iPTH levels higher than 300 pg/mL.
Recognizing the need to improve phosphorus control—since “most data indicate that fewer than 30% of dialysis patients are able to maintain phosphorus in the suggested target range” of 3.5 to 5.5 mg/dL—K/DOQI suggests that “successful implementation will require an increased dietitian-to-patient ratio, educational tools to increase patient compliance, as well as studies to further explore the feasibility of dialytic techniques that are better able to control serum phosphorus levels (such as nocturnal or daily hemodialysis), and the widespread availability and affordability of different phosphate binders, regardless of patient insurance.”