Chronic Kidney Disease (CKD): Lessening the Phosphate Burden

Overview:

The central role for total body phosphate retention will be emphasized in the pathophysiology of CKD-MBD (chronic kidney disease -mineral bone disorder). Phosphate retention either directly or indirectly accounts for many of the complications and progression of CKD. The relationship between circulating phosphate, ionized and total calcium, PTH, FGF23, and Klotho will be introduced. The ability to measure the master phosphate in FGF23 has recently become available – this allows detection of total body phosphate retention even when the circulating phosphate is within the reference range. Dietary restriction of phosphate is the first step in reducing phosphate retention. Adding intestinal phosphate binders to the diet is the next step to gain targeted circulating phosphate. Intestinal phosphate binders (salts of aluminum, calcium, lanthanum, iron) will be compared for their efficacy in binding phosphate and their level of safety. Too much phosphorus restriction, especially in early IRIS CKD stages in cats, can create hypercalcemia that is damaging the kidneys.

Learning Objectives:

• Describe to a client why it is important to reduce phosphorus retention in dogs or cats with CKD.
• Implement a plan using some combination of phosphate restricted diets and intestinal phosphate binders to gain “targeted” control of serum phosphorus during CKD.
• Compare and contrast the advantages and possible adverse effects from the use of the various classes of intestinal phosphate binders (salts of aluminum, calcium, lanthanum, and iron).