From the Guidelines
Loop diuretics like furosemide, bumetanide, and torsemide commonly cause hypocalcemia by increasing urinary calcium excretion, and patients on these medications should be monitored regularly for calcium imbalances, especially those with pre-existing calcium disorders or at risk for hypocalcemia 1. When treating patients with loop diuretics, it is essential to monitor serum calcium levels regularly, especially in those with pre-existing calcium disorders or at risk for hypocalcemia.
- If hypocalcemia develops, consider calcium supplementation with calcium carbonate 500-1000 mg 2-3 times daily or calcium citrate 250-500 mg 2-3 times daily.
- For severe symptomatic hypocalcemia, intravenous calcium gluconate 1-2 g may be necessary.
- Thiazide diuretics have the opposite effect on calcium, reducing urinary calcium excretion, so they may be preferred in patients with hypocalcemia or conditions like osteoporosis. The calcium-wasting effect of loop diuretics can be beneficial in treating hypercalcemia, but this same mechanism increases the risk of bone demineralization with long-term use 1. Vitamin D supplementation (800-1000 IU daily) may also be appropriate for patients on chronic loop diuretic therapy to support calcium homeostasis and bone health. It is crucial to note that the management of calcium imbalance in patients on loop diuretics should be individualized, taking into account the patient's underlying condition, renal function, and other medications that may affect calcium levels 1.
From the Research
Calcium Imbalance in Loop Diuresis
- Loop diuretics promote renal calcium excretion, which can lead to hypocalcemia 2, 3
- The mechanism of loop diuretics involves inhibiting the Na-K-2Cl transporter, resulting in increased calcium excretion 3
- Loop diuretics are often used in the treatment of hypercalcemia due to their ability to increase calcium excretion 3
- In contrast, thiazide diuretics decrease calcium excretion by blocking the thiazide-sensitive NaCl transporter in the distal convoluted tubule 2, 3
- Carbonic anhydrase inhibitors can also increase calcium excretion, but their use can promote nephrocalcinosis and nephrolithiasis 3
Diagnosis and Management of Calcium Imbalance
- Hypocalcemia can be caused by various disorders, including postsurgical hypoparathyroidism, and can range from asymptomatic to life-threatening conditions 4
- Intravenous calcium infusion is essential to raise calcium levels and resolve or minimize symptoms in the setting of acute hypocalcemia 4
- Oral calcium and/or vitamin D supplementation is the most frequently used treatment for chronic hypocalcemia 4
- In hypercalcemia, treatment reduces serum calcium and improves symptoms, at least transiently, and the underlying cause of hypercalcemia should be identified and treated 5, 6
Hypercalcemia and Hypocalcemia
- Hypercalcemia affects approximately 1% of the worldwide population, and can be caused by primary hyperparathyroidism, malignancy, and other factors 6
- Hypercalcemia can be asymptomatic or symptomatic, with symptoms ranging from fatigue and constipation to nausea, vomiting, dehydration, confusion, somnolence, and coma 6
- Hypocalcemia can be caused by vitamin D deficiency, and symptomatic patients and patients with calcium levels less than 7.6 mg/dL should be treated with intravenous calcium gluconate 5