From the Guidelines
The most appropriate management for this 73-year-old woman with stage G4 chronic kidney disease is option D, a low phosphate diet. This patient has hyperphosphatemia (phosphorus level of 5.4 mg/dL, which is above the normal range) in the setting of advanced CKD. Dietary phosphate restriction is the first-line intervention for managing hyperphosphatemia in CKD before initiating phosphate binders, as suggested by the Kidney Disease: Improving Global Outcomes 2017 clinical practice guideline update 1. The patient's parathyroid hormone level is only mildly elevated, which is expected in stage G4 CKD and does not yet warrant treatment with calcitriol or cinacalcet. Her calcium level is normal, so calcium acetate would not be appropriate as it could increase the risk of hypercalcemia, and recent studies have shown that higher serum calcium concentrations have been linked to increased mortality in adults with CKD 1. Sevelamer would be considered if dietary modifications alone fail to control phosphorus levels. Controlling phosphate levels is important to prevent secondary hyperparathyroidism progression, vascular calcification, and bone disease in CKD patients. Key considerations in managing this patient include avoiding hypercalcemia, as suggested by the guideline 1, and focusing on prevention of hyperphosphatemia, which may be valuable in patients with CKD stage G3a to G5D. In terms of specific management, the guideline suggests that treatment should be focused on patients with hyperphosphatemia, rather than maintaining normal phosphate levels in all patients 1. Overall, a low phosphate diet is the most appropriate initial management strategy for this patient, with careful monitoring of phosphate and calcium levels to guide further treatment.
From the FDA Drug Label
A serum iPTH level of ≥ 100 pg/mL is strongly suggestive of secondary hyperparathyroidism. Calcitriol is indicated in the management of secondary hyperparathyroidism and resultant metabolic bone disease in patients with moderate to severe chronic renal failure (Ccr 15 to 55 mL/min) not yet on dialysis. Cinacalcet tablets are not indicated for use in patients with CKD who are not on dialysis because of an increased risk of hypocalcemia
The patient has a serum iPTH level of 97 pg/mL, which is close to the threshold for secondary hyperparathyroidism, and an estimated glomerular filtration rate of 24 mL/min/1.73 m2, indicating moderate to severe chronic renal failure. Calcitriol is the most appropriate management option for this patient, as it is indicated for the management of secondary hyperparathyroidism in patients with moderate to severe chronic renal failure not yet on dialysis 2. Cinacalcet is not indicated for patients with CKD who are not on dialysis due to the increased risk of hypocalcemia 3 3.
From the Research
Management of Hyperphosphatemia in Chronic Kidney Disease
The patient's laboratory results show a phosphorus level of 5.4 mg/dL, which is elevated. According to the studies, hyperphosphatemia is a common complication in chronic kidney disease (CKD) and is associated with increased cardiovascular morbidity and mortality 4, 5.
Treatment Options
The treatment options for hyperphosphatemia include:
- Diminishing intestinal phosphate absorption by a low phosphate diet and phosphate binders 4
- Phosphate binders such as calcium-based salts, sevelamer, and lanthanum carbonate 4, 5, 6
- The choice of phosphate binder should be individualized, considering the clinical context, costs, and individual tolerability 4
Phosphate Binders
The studies compared the efficacy and safety of different phosphate binders:
- Calcium-based binders are effective but may contribute to total body calcium overload and vascular calcification 6
- Sevelamer is a non-calcium-based binder that does not increase total body calcium load and has pleiotropic effects that may impact cardiovascular disease 4, 5
- Lanthanum carbonate is a potent and selective phosphate binder that retains high affinity for phosphate over a wide pH range and does not bind bile acids or contribute to metabolic acidosis 6
Recommended Management
Based on the patient's laboratory results and medical history, the most appropriate management would be to prescribe a phosphate binder. Considering the patient's elevated phosphorus level and normal calcium level, a non-calcium-based phosphate binder such as sevelamer would be a suitable option.
Best Answer
The best answer is E, Sevelamer, or alternatively, B, Calcium acetate, could be considered if the patient's calcium level was not a concern. However, given the patient's normal calcium level, sevelamer would be a better option to avoid potential hypercalcemia and vascular calcification.