A client with chronic kidney disease develops hypocalcemia. Which electrolyte imbalance is most commonly associated with this condition?

Managing chronic kidney disease requires understanding the reciprocal relationship between calcium and phosphorus. Knowledge of renal osteodystrophy, vitamin D activation, and the role of the parathyroid hormone in mineral homeostasis is essential to identify the associated electrolyte shift. Choice A rationale Hypokalemia is not the primary association with hypocalcemia in kidney failure. Chronic kidney disease usually results in hyperkalemia, where potassium exceeds 5.0 mEq/L, because the failing kidneys cannot effectively excrete excess potassium ions into the urine. Choice B rationale Hypernatremia is an elevation of sodium above 145 mEq/L and is not directly linked to the calcium-phosphorus axis. While fluid balance is impaired in renal failure, sodium levels vary based on fluid volume status rather than hypocalcemia. Choice C rationale In kidney failure, phosphorus excretion decreases, leading to hyperphosphatemia. High serum phosphorus (above 4.5 mg/dL) binds with calcium, causing hypocalcemia (below 8.5 mg/dL). Additionally, decreased vitamin D activation in the kidneys further reduces calcium absorption from the gut. Choice D rationale Hyponatremia, or sodium below 135 mEq/L, often results from fluid overload in renal patients but is not the metabolic driver of low calcium. The hallmark mineral imbalance involves the inverse relationship specifically between serum phosphate and ionized calcium.