From the Guidelines
The patient's calcium level has improved from 11.0 to 10.4 mg/dL but remains slightly elevated, with a normal intact parathyroid hormone (PTH) level, suggesting non-parathyroid-mediated hypercalcemia. This pattern suggests that the hypercalcemia is not due to primary hyperparathyroidism, but rather another cause such as hypercalcemia of malignancy, medications (thiazide diuretics, lithium), granulomatous diseases, or hyperthyroidism. Further evaluation is recommended, including checking vitamin D levels, phosphorus, alkaline phosphatase, and urinary calcium excretion, as well as screening for malignancy, particularly multiple myeloma (serum protein electrophoresis) 1. Treatment should focus on addressing the underlying cause of the hypercalcemia, and may include increased hydration, limiting calcium intake, and avoiding thiazide diuretics. If symptoms of hypercalcemia are present (confusion, weakness, kidney stones, bone pain), more aggressive management may be needed. The normal PTH with elevated calcium is key - in primary hyperparathyroidism, PTH would typically be elevated or inappropriately normal despite hypercalcemia, while in other causes, PTH should be suppressed. Regular monitoring of calcium levels is necessary to prevent potential complications such as cardiovascular events and bone disease 1. It is also important to note that the use of calcium-based phosphate binders should be restricted in patients with hyperphosphatemia across the CKD spectrum, as they may contribute to hypercalcemia 1. Overall, a comprehensive approach to managing hypercalcemia in patients with CKD is necessary to prevent morbidity and mortality.
From the Research
Calcium Levels and PTH
- The patient's calcium level decreased from 11.0 to 10.4, which is still within a relatively normal range 2.
- Normal intact PTH (parathyroid hormone) levels are crucial for maintaining calcium homeostasis in the body 2.
- Hypocalcemia, or low serum calcium, can occur in conjunction with multiple disorders and can be life-threatening if severe 2.
Hypocalcemia and Its Management
- Disorders that disrupt the metabolism of vitamin D can lead to chronic hypocalcemia, as vitamin D is responsible for increasing the gut absorption of dietary calcium 2.
- Treatment and management options for chronic hypocalcemia vary depending on the underlying disorder 2.
- In patients with hypoparathyroidism, calcium and vitamin D supplementation must be carefully titrated to avoid symptoms of hypocalcemia while keeping serum calcium in the low-normal range to minimize hypercalciuria, which can lead to renal dysfunction 2.
Denosumab and Hypocalcemia
- Denosumab is a human monoclonal antibody antiresorptive agent used for the treatment of bone metastasis in different cancer types, including breast cancer 3.
- Hypocalcemia is a known adverse effect of denosumab, and early supplementation plays an important role in the prevention and management of hypocalcemia 3.
- Proposed risk factors for denosumab-associated hypocalcemia include poor renal function, hypoparathyroidism, insufficient calcium intake, and diffuse metastatic bone disease 3.
Calcium Supplementation and Bone Health
- Supplemental calcium is also generally recommended for postmenopausal osteoporosis, and bisphosphonates such as alendronate are widely used for this condition 4.
- Alendronate, vitamin D, and calcium are safe and potentially useful in the treatment of osteopenia/osteoporosis associated with HIV infection 5.
- Denosumab can be considered for patients with chronic kidney disease, but it is essential to assess for and optimize CKD-mineral and bone disorders (CKD-MBD) prior to initiating treatment, and to supplement with calcium and vitamin D 6.