As a nephrology pharmacy specialist, you will be asked how to manage hyperphosphatemia during transitions of care in patients with severe chronic kidney disease. High phosphorus levels cause hypocalcemia, which triggers parathyroid hormone release. This can lead to fractures, vascular calcification, and is linked to increased mortality.
Expect maintenance binders (see Table 1) to be saved for persistently elevated phosphate levels. Any binder can lower phosphorus levels by about 1 to 2 mg/dL, but none is shown to improve outcomes. Most patients will start with a calcium-based binder like calcium carbonate (Cal-Preg, Calcimate, etc) or acetate (Marcal, etc). They cost the least. Some experts avoid these due to concerns of vascular calcification. But recent evidence suggests calcium-based binders don't increase cardiovascular (CV) risk compared to those without calcium.
| Table (1). Phosphorus binders | |||||
|---|---|---|---|---|---|
| Phosphorus binder | Dose | Number of pills to reach PBED 6 g | Formulation | Advantages | Disadvantages |
| Calcium carbonate | 750–3500 mg | 8 | Swallowed and chewable tablets | Low cost, over-the-counter | Calcium burden |
| Calcium acetate | 667–6000 mg | 9 | Swallowed tablet | Less calcium than calcium carbonate | Needs prescription |
| Lanthanum | 500–3750 mg | 3 | Chewable and swallowed tablet (can be crushed) | Lower pill burden than many other binders | Expensive |
| Sevelamer | 800–8000 mg | 10 | Swallowed tablet and granule packets | Lowers low-density lipoprotein cholesterol | High pill burden |
| Sucroferric oxyhydroxide | 500–3000 mg | 3.75 | Chewable tablet | Lower pill burden | Cost and gastrointestinal side effects |
| Ferric citrate | 210–2500 mg | 9 | Swallowed tablet | Improves iron parameters | Expensive |
| PBED = phosphorus binder equivalent dose. Information from Cleveland Clinic Journal of Medicine August 2018, 85 (8) 629-638; DOI: https://doi.org/10.3949/ccjm.85a.17054 |
|||||
Expect sevelamer (Renagel) or lanthanum (Fosrenol) to be saved for patients with hypercalcemia. Generally continue binders during a hospital stay for patients who are eating. Verify binders are scheduled with meals, not just "TID (Three Times a Day)". Switch to a formulary binder if needed. But check calcium before using a calcium-based binder. Assess individual calcium and phosphorus levels rather than calculating a calcium-phosphate product.
If tube feeds are started, work with the dietician or NUTRITIONIST to try a low-phosphorus formula and consider temporarily stopping the binder (see Table 2). But if phosphate levels continue to rise, consider restarting the binder. Check whether you can crush it first and evaluate frequency. For example, switch sevelamer tabs (Renagel) to suspension since tabs can clog the tube. Consider scheduling as often as every 4 hours with tube feeding, if needed. Keep in mind to temporarily stop binders during continuous renal replacement therapy (CRRT), it often leads to hypophosphatemia.
| Table (2). Phosphate content of foods | |
|---|---|
| Type | Food |
| High phosphate-to-protein ratio (avoid in end-stage kidney disease) | Egg yolk |
| Beans, lentils, and dried peas | |
| Cheese | |
| Milk | |
| Nuts and seeds | |
| Organ meats and certain seafoods like shrimp, crab, and oysters | |
| Low phosphate-to-protein ratio | Egg white |
| White bread, pasta, crackers | |
| Soups that are water-based or broth-based | |
| Seafoods like sea bass | |
| Information from Cleveland Clinic Journal of Medicine August 2018, 85 (8) 629-638; DOI: https://doi.org/10.3949/ccjm.85a.17054 | |
REFERENCES
-
Kidney Disease: Improving Global Outcomes (KDIGO) CKD-MBD Update Work Group. KDIGO 2017 Clinical Practice Guideline Update for the Diagnosis, Evaluation, Prevention, and Treatment of Chronic Kidney Disease-Mineral and Bone Disorder (CKD-MBD). Kidney Int Suppl (2011). 2017 Jul;7(1):1-59. Available at: https://www.kisupplements.org/article/S2157-1716(17)30001-1/fulltext
Sekar A, Kaur T, Nally JV, Rincon-Choles H, Jolly S, Nakhoul GN. Phosphorus binders: The new and the old, and how to choose. Cleve Clin J Med. 2018 Aug;85(8):629-638. Available at: https://www.ccjm.org/content/85/8/629 or https://pubmed.ncbi.nlm.nih.gov/30102593
Hutchison AJ. Oral phosphate binders. Kidney Int. 2009 May;75(9):906-14. Available at: https://www.kidney-international.org/article/S0085-2538(15)53824-6/fulltext
Stromont R, McCoy R, Bashir K, Malesker MA. New pharmacotherapy options for hyperphosphatemia. March 17, 2016. https://www.uspharmacist.com/article/new-pharmacotherapy-options-for-hyperphosphatemia