Phosphate Shifts in Renal

The renal phosphate problem addressed here is primarily phosphate retention in chronic kidney disease (CKD). As functioning nephrons and glomerular filtration decline, the kidneys cannot excrete the phosphate delivered from food and normal cellular metabolism. Serum phosphate gradually rises. The consequence is broader than one abnormal laboratory value. A rising phosphate level contributes to an abnormal calcium–phosphate balance and stimulates parathyroid hormone (PTH), producing the mineral and bone disorder associated with CKD. The process is usually cumulative, so a client may look well while the biochemical disturbance is worsening. In adults, hyperphosphatemia is defined as a serum phosphate concentration above 1.45 mmol/L (1.45 mmol/L). Interpret the result with the calcium level, PTH, kidney function, dialysis status, and the direction of change. A single mildly elevated result does not carry the same urgency as a rapidly rising level accompanied by neuromuscular symptoms or failure of treatment. The central clinical question is not simply, “Is the phosphate high?” It is, “How high is it, what has happened to calcium and PTH, has treatment been taken correctly, and is the client developing an...