From the Guidelines
Hyzaar is unlikely to directly cause hypercalcemia, but the hydrochlorothiazide component can cause mild hypercalcemia in some patients by reducing urinary calcium excretion. Hyzaar is a combination medication containing losartan (an angiotensin II receptor blocker) and hydrochlorothiazide (a thiazide diuretic). While the losartan component does not affect calcium levels, the hydrochlorothiazide component can increase calcium reabsorption in the distal tubules of the kidneys, leading to mild hypercalcemia in some patients 1, 2.
Key Points to Consider
- The effect of hydrochlorothiazide on calcium levels is typically modest, and clinically significant hypercalcemia from Hyzaar alone is uncommon.
- If a patient taking Hyzaar develops hypercalcemia, other causes should be investigated, such as hyperparathyroidism, malignancy, vitamin D excess, or other medications.
- Patients with pre-existing calcium metabolism disorders should be monitored more closely when taking Hyzaar.
- If hypercalcemia develops while on Hyzaar, a healthcare provider may consider switching to a different antihypertensive medication that doesn't contain a thiazide diuretic.
Monitoring and Management
- Monitor patients taking Hyzaar for signs of hypercalcemia, such as elevated calcium levels, kidney stones, or bone pain.
- Consider alternative antihypertensive medications for patients with pre-existing calcium metabolism disorders or those who develop hypercalcemia while taking Hyzaar.
- Investigate other causes of hypercalcemia in patients taking Hyzaar who develop elevated calcium levels.
From the FDA Drug Label
Parathyroid Disease Calcium excretion is decreased by thiazides, and pathologic changes in the parathyroid glands, with hypercalcemia and hypopharmdess, have been observed in a few patients on prolonged thiazide therapy.
Hypercalcemia can be a potential side effect of Hyzaar (Losartan/Hydrochlorothiazide) due to the thiazide component, as it can cause decreased calcium excretion and pathologic changes in the parathyroid glands. This is supported by the information found in the drug label for hydrochlorothiazide 3.
From the Research
Hyzaar (Losartan/Hydrochlorothiazide) and Hypercalcemia
- Hyzaar is a combination medication containing losartan and hydrochlorothiazide, used to treat high blood pressure and protect the kidneys from damage due to diabetes 4.
- Hypercalcemia, or elevated calcium levels in the blood, can be caused by various factors, including hyperparathyroidism, malignancy, and certain medications such as thiazide diuretics 4, 5.
- Thiazide diuretics, like hydrochlorothiazide, can cause hypercalcemia by increasing calcium reabsorption in the kidneys 5, 6.
- A case report described a patient who developed severe hypercalcemia due to thiazide-induced hypercalcemia, highlighting the importance of monitoring electrolytes in patients taking thiazide diuretics 5.
- Another study found that thiazides may be safe and effective in patients with primary hyperparathyroidism, but careful monitoring for hypercalcemia is required 6.
Mechanism of Hypercalcemia in Hyzaar
- The hydrochlorothiazide component of Hyzaar can increase calcium reabsorption in the kidneys, leading to hypercalcemia 5, 6.
- Additionally, the use of calcium and vitamin D supplements with thiazide diuretics can increase the risk of hypercalcemia 7, 8.
- A case report described a patient who developed severe hypercalcemia due to the combination of vitamin A supplementation, hydrochlorothiazide, and primary hyperparathyroidism 8.
Clinical Implications
- Patients taking Hyzaar should be monitored for signs and symptoms of hypercalcemia, such as nausea, vomiting, and altered mental status 4, 5.
- Electrolyte levels, including calcium, should be regularly checked in patients taking thiazide diuretics 5, 6.
- The use of calcium and vitamin D supplements with thiazide diuretics should be carefully considered, and patients should be educated on the potential risks of hypercalcemia 7, 8.