The most appropriate next step in management is to begin oral calcitriol. This patient has secondary hyperparathyroidism due to severe chronic kidney disease (CKD). The first priority in treating these patients is to attempt to normalize calcium and phosphorus levels and treat vitamin D deficiency, if present. This patient has normal calcium, phosphorus, and 25-hydroxy vitamin D levels. If vitamin D levels are robust and the phosphorus level is normal, but the parathyroid hormone (PTH) level is elevated above target levels, active vitamin D analogues should be initiated. This is because 1-α hydroxylation of 25-hydroxy vitamin D is impaired in most patients with severe CKD, and these patients should begin oral calcitriol (1,25-dihydroxy vitamin D) or a calcitriol analogue (such as paricalcitol or doxercalciferol) to maintain bone health. Calcitriol directly suppresses PTH production by the parathyroid glands, thereby protecting bones from osteitis fibrosa cystica, which can occur as a result of chronic secondary hyperparathyroidism. Vitamin D analogues should be discontinued in the setting of hypercalcemia or hyperphosphatemia.

Bisphosphonates may be used in the treatment of osteoporosis. However, bisphosphonates may actually worsen some types of bone disease observed in the setting of CKD, especially adynamic bone disease.

Current Kidney Disease Improving Global Outcomes (KDIGO) guidelines do not recommend the routine use of dual-energy x-ray absorptiometry (DEXA) scans in patients with CKD because DEXA has poor predictive value for distinguishing histologic subtypes of bone disease in patients with CKD.

This patient does not have primary hyperparathyroidism, which is typically characterized by inappropriately elevated PTH levels in the setting of hypercalcemia. She has secondary hyperparathyroidism, which is driven by multiple factors, including reduced renal production of calcitriol and factors that are often present in patients with CKD such as hyperphosphatemia and hypocalcemia. Parathyroidectomy is reserved for patients with secondary hyperparathyroidism that is refractory to medical therapy (often referred to as tertiary hyperparathyroidism).