Does hyperparathyroidism (Hyperparathyroidism) cause hypomagnesemia (low magnesium)?

From the Guidelines

Hyperparathyroidism can indeed cause low magnesium levels in the body, as elevated parathyroid hormone (PTH) increases urinary magnesium excretion, leading to magnesium wasting through the kidneys. This condition often coexists with vitamin D deficiency, which further impairs magnesium absorption in the intestines, creating a complex relationship where calcium, phosphorus, and magnesium homeostasis become disrupted 1. Patients with hyperparathyroidism should have their magnesium levels monitored regularly, as persistent hypomagnesemia can worsen the clinical manifestations of the disease and make it more difficult to correct calcium imbalances.

Key Considerations

• Elevated PTH increases urinary magnesium excretion, leading to magnesium wasting through the kidneys
• Vitamin D deficiency, which often coexists with hyperparathyroidism, impairs magnesium absorption in the intestines
• Magnesium deficiency can increase PTH resistance and exacerbate the condition
• Monitoring magnesium levels and correcting magnesium deficiency is essential for the effective management of hyperparathyroidism

Treatment Approach

• Addressing the underlying hyperparathyroidism (either surgically or medically) while supplementing with oral magnesium preparations such as magnesium oxide (400-800 mg daily) or magnesium citrate (200-400 mg daily) is a common treatment approach 1
• Severe cases may require intravenous magnesium replacement
• Oral or enteral feeding should be advocated unless contraindicated or prevented by the underlying intestinal disease, and oral calcium and magnesium supplementation should be prescribed whenever possible 1

Prevention of Magnesium Deficiency

• Prevention of magnesium deficiency related to HPN factors is based on the optimization of the parenteral solution, with particular attention paid to the calcium/phosphate ratio in the solution 1
• The amounts of calcium, magnesium, and phosphate provided should aim to maintain normal serum concentrations and 24-h urinary excretion
• Normal vitamin D nutritional status is represented by normal serum concentrations of 25-hydroxivitamin D and 1,25-dihydroxyvitamin D, and excess of vitamin D should be avoided because it may result in net bone resorption and thus in bone demineralization 1

From the Research

Hyperparathyroidism and Magnesium Levels

• Hyperparathyroidism can lead to low magnesium levels, as evidenced by a study that found hypomagnesemia in 25.1% of patients with primary hyperparathyroidism 2.
• The relationship between parathyroid hormone (PTH) and magnesium levels is complex, with some studies suggesting that PTH can influence magnesium metabolism 3.
• Magnesium deficiency can impair PTH secretion, leading to hypocalcemia 4, 5.
• In patients with secondary hyperparathyroidism, parathyroidectomy can lead to a drop in serum magnesium levels, which then gradually restore 3.

Mechanisms and Associations

• Lower serum magnesium levels have been associated with lower hemoglobin levels in patients with primary hyperparathyroidism, independent of serum calcium, albumin, and PTH 2.
• Magnesium supplementation does not affect blood calcium levels in treated hypoparathyroid patients, but can lead to a small increase in plasma magnesium levels 6.
• The derangement of magnesium homeostasis is consistent with the derangement of calcium/phosphorus homeostasis in patients with secondary hyperparathyroidism 3.

Clinical Implications

• Hypomagnesemia is a common electrolyte disorder in patients with primary hyperparathyroidism, and is independently associated with lower hemoglobin levels 2.
• The therapeutic strategies to achieve optimum serum magnesium levels in patients with hyperparathyroidism should take into account the varying stages of disease development, as PTH can influence magnesium metabolism 3.