How should I treat hypomagnesemia in Acute Kidney Injury (AKI)?

From the Guidelines

To treat hypomagnesemia in acute kidney injury (AKI), the most effective approach is to use dialysis solutions containing magnesium, as recommended by the most recent and highest quality study 1. This approach can help prevent the onset of hypomagnesemia, which is a common complication in patients undergoing kidney replacement therapy (KRT). The use of dialysis solutions with increased magnesium concentration may be particularly beneficial in preventing KRT-related hypomagnesemia, especially when regional citrate anticoagulation is utilized 1. Some key points to consider when treating hypomagnesemia in AKI include:

• Monitoring serum magnesium levels closely, especially in patients undergoing KRT
• Adjusting the dialysis solution composition to prevent electrolyte disorders, including hypomagnesemia
• Avoiding the use of magnesium-containing medications, such as antacids and laxatives, which can exacerbate hypermagnesemia
• Being aware of the potential risks of hypermagnesemia, including hypotension, respiratory depression, and loss of deep tendon reflexes
• Considering the use of oral magnesium supplements, such as magnesium oxide or magnesium citrate, for mild cases or maintenance therapy, but with caution and close monitoring in patients with AKI 1. It's also important to note that hypomagnesemia can worsen outcomes in AKI by contributing to arrhythmias, muscle weakness, and potentially prolonging renal recovery, and that concurrent electrolyte abnormalities, particularly hypokalemia and hypocalcemia, often accompany hypomagnesemia and may need simultaneous correction 1.

From the FDA Drug Label

In the treatment of mild magnesium deficiency, the usual adult dose is 1 g, equivalent to 8. 12 mEq of magnesium (2 mL of the 50% solution) injected IM every six hours for four doses (equivalent to a total of 32.5 mEq of magnesium per 24 hours). For severe hypomagnesemia, as much as 250 mg (approximately 2 mEq) per kg of body weight (0. 5 mL of the 50% solution) may be given IM within a period of four hours if necessary. Alternatively, 5 g (approximately 40 mEq) can be added to one liter of 5% Dextrose Injection, USP or 0. 9% Sodium Chloride Injection, USP for slow IV infusion over a three-hour period. In the treatment of deficiency states, caution must be observed to prevent exceeding the renal excretory capacity.

The treatment of hypo magnesium in AKI should be approached with caution due to the potential for renal excretory capacity to be compromised.

• The usual adult dose for mild magnesium deficiency is 1 g (8.12 mEq) every six hours for four doses.
• For severe hypomagnesemia, the dose can be increased to 250 mg (2 mEq) per kg of body weight within a period of four hours if necessary.
• Alternatively, 5 g (40 mEq) can be added to one liter of 5% Dextrose Injection or 0.9% Sodium Chloride Injection for slow IV infusion over a three-hour period. It is essential to monitor serum magnesium levels and adjust the dose accordingly to prevent exceeding the renal excretory capacity 2 2.

From the Research

Treatment of Hypomagnesemia in AKI

• Hypomagnesemia is a common electrolyte disorder in critically ill patients with acute kidney injury (AKI) and is associated with increased morbidity and mortality risk 3, 4, 5.
• The treatment of hypomagnesemia in AKI patients involves early intravenous magnesium supplementation and close monitoring of serum magnesium levels, especially in the setting of regional citrate anticoagulation (RCA) 3.
• Increasing the magnesium content of dialysis/replacement solutions may also decrease the risk of hypomagnesemia, but the optimal concentration has not yet been identified 3.
• Magnesium abnormalities, including hypomagnesemia and hypermagnesemia, have been associated with adverse kidney outcomes and mortality in critically ill patients 4, 5.

Management Strategies

• Early magnesium supplementation and close monitoring of serum magnesium levels can help reduce the risk of hypomagnesemia in AKI patients 3, 6, 7.
• The composition of kidney replacement therapy (KRT) fluids and dialysis prescriptions should be tailored to individual patient needs to minimize the risk of hypomagnesemia 3.
• Monitoring serum magnesium levels and correcting magnesium derangements may help prevent the progression of AKI to acute kidney disease (AKD) 5.

Clinical Considerations

• Hypomagnesemia can occur due to insufficient magnesium intake, increased gastrointestinal or renal loss, or redistribution from extracellular to intracellular compartments 6.
• Certain drugs, such as proton pump inhibitors (PPIs), can cause hypomagnesemia 6.
• Serum magnesium levels should be measured directly in clinical circumstances where a risk for magnesium deficiency exists, and appropriately corrected when found 7.