Phosphate Management in Chronic Kidney Disease

Introduction to Phosphate Binders

A dialysate calcium concentration of <1.25 mmol/L is associated with intradialytic cardiovascular instability, suggesting calcium fluctuations can impact cardiac function, according to the Kidney International guidelines 1
Calcium-containing phosphate binders increase the risk of vascular calcification progression, which can lead to cardiovascular complications, as reported by the Kidney International guidelines 1

For patients with severe hyperphosphatemia, aluminum-based binders may be used short-term (4 weeks only) for serum phosphorus levels >7.0 mg/dL, and more frequent dialysis should also be considered for these patients, as recommended by the American Journal of Kidney Diseases guidelines 2
Phosphate binders should be initiated when phosphorus exceeds target levels (>4.6 mg/dL) despite dietary restriction, as recommended by the American Journal of Kidney Diseases guidelines 2
Calcium-based phosphate binders are recommended as the initial therapy for hyperphosphatemia in patients with chronic kidney disease, particularly in early stages (CKD 3-4) 2
Non-calcium phosphate binders, such as sevelamer hydrochloride/carbonate, are recommended for patients with hypercalcemia (corrected calcium >10.2 mg/dL), low PTH levels (<150 pg/mL on two consecutive measurements), or severe vascular or soft tissue calcifications, according to the American Journal of Kidney Diseases guidelines and the Annals of Internal Medicine guidelines 2, 3
Combination therapy with calcium and non-calcium binders may be considered for patients with persistent hyperphosphatemia (>5.5 mg/dL) despite monotherapy, as recommended by the American Journal of Kidney Diseases guidelines and the Annals of Internal Medicine guidelines 2, 3

The target phosphorus levels for CKD stages 3-4 are 2.7-4.6 mg/dL, and for CKD stage 5 (dialysis), the target phosphorus levels are 3.5-5.5 mg/dL, as recommended by the American Journal of Kidney Diseases guidelines and supported by the 2018 KDIGO guidelines 2
Serum phosphorus levels should be monitored monthly after initiating therapy, and calcium levels should be maintained within the normal range (8.4-9.5 mg/dL) and corrected for albumin if albumin levels are abnormal 2, 4
The calcium-phosphorus product should be maintained <55 mg²/dL² 2

Total elemental calcium from phosphate binders should not exceed 1,500 mg/day, and total calcium intake (dietary + binders) should not exceed 2,000 mg/day, as recommended by the American Journal of Kidney Diseases guidelines 2
Failing to correct calcium for albumin when evaluating calcium status can lead to inaccurate assessments 4
Exceeding recommended calcium intake limits (2,000 mg/day total) can increase the risk of cardiovascular complications 2
Using calcium-based binders in patients with hypercalcemia or low PTH is not recommended 2
Not administering phosphate binders with meals can reduce their effectiveness 2
Continuing aluminum-based binders beyond 4 weeks is not recommended due to the risk of toxicity 2
Using calcium citrate with aluminum-based binders can increase aluminum absorption and is not recommended 2