How should I manage elevated phosphate levels in a patient with CKD-MBD, and when should I consider referral to a specialist?

Management of elevated phosphate levels in CKD-MBD:

• Start with dietary phosphate management tailored by a specialist renal dietitian, focusing on controlling intake of phosphate-rich foods and phosphate additives while maintaining adequate protein intake to avoid malnutrition.
• Before initiating phosphate binders, optimize diet and dialysis if applicable.
• For adults with CKD stage 4 or 5 and hyperphosphataemia, offer calcium acetate as the first-line phosphate binder to control serum phosphate levels.
• If calcium acetate is contraindicated (e.g., due to hypercalcaemia or low serum parathyroid hormone) or not tolerated, offer sevelamer carbonate.
• If neither calcium acetate nor sevelamer carbonate can be used, consider sucroferric oxyhydroxide (for adults on dialysis if a calcium-based binder is not needed) or calcium carbonate (if a calcium-based binder is needed).
• Lanthanum carbonate should only be considered if other phosphate binders cannot be used.
• If hyperphosphataemia persists despite maximum tolerated doses of a calcium-based phosphate binder, check adherence and consider combining it with a non-calcium-based phosphate binder.
• Monitor serum calcium and phosphate regularly, especially when using alfacalcidol or calcitriol supplements.

Referral to specialist:

• Measure serum calcium, phosphate, and parathyroid hormone concentrations in adults with GFR less than 30 ml/min/1.73 m² (CKD stage 4 or 5) and determine testing frequency based on results and clinical context; seek specialist opinion if uncertain.
• Refer adults with CKD for specialist assessment if there is doubt about management, or if they meet referral criteria such as rapid decline in eGFR, poorly controlled hypertension despite multiple medications, or other complications.
• Consider discussing management with a specialist by letter, email, telephone, or virtual meeting if there are concerns but the patient does not need immediate specialist review.
• Referral is also indicated if symptoms of CKD-MBD persist despite correction of vitamin D deficiency and treatment.