What dose of magnesium (Mg) should be given to increase the magnesium level in a patient with hypomagnesemia?

From the Guidelines

I recommend administering 12-24 mmol of magnesium oxide daily, given as gelatine capsules of 4 mmol magnesium oxide (160 mg of MgO) at night, to increase the magnesium level in a patient with a magnesium level of 1.8 mg/dL, as this is the most effective and safest method for mild hypomagnesemia, according to the most recent and highest quality study 1. To determine the best course of treatment, it is essential to consider the severity of the hypomagnesemia and the patient's overall health status.

• The patient's magnesium level of 1.8 mg/dL indicates mild hypomagnesemia, which can be treated with oral magnesium supplementation.
• Magnesium oxide is a commonly used and effective form of magnesium supplementation, as it contains more elemental magnesium than other salts and is soluble in dilute acid, allowing for better absorption in the stomach 1.
• The recommended dose of 12-24 mmol of magnesium oxide daily, given as gelatine capsules of 4 mmol magnesium oxide (160 mg of MgO) at night, is based on the guidelines for management of patients with a short bowel, which suggests that this dose is effective in correcting hypomagnesemia 1.
• It is also important to note that oral magnesium supplements may not always be successful in normalizing magnesium levels, and intravenous supplementation may be required in some cases, as suggested by the ESPEN guidelines on parenteral nutrition 1.
• Additionally, the patient's renal function should be taken into account when administering magnesium supplements, as reduced doses may be necessary in patients with renal impairment, as mentioned in the example answer.
• The most recent study from 2024 1 provides guidance on the prevention and treatment of electrolyte disorders, including hypomagnesemia, in patients with acute or chronic kidney disease, but it does not provide specific recommendations for the treatment of mild hypomagnesemia in patients without kidney disease.
• Therefore, based on the available evidence, the recommended treatment for a patient with a magnesium level of 1.8 mg/dL is oral magnesium supplementation with magnesium oxide, as described above.

From the FDA Drug Label

In Magnesium Deficiency 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. A serum magnesium level of 6 mg/100 mL is considered optimal for control of seizures.

The patient has a magnesium level of 1.8, which is lower than the optimal level of 6 mg/100 mL.

• The dose to increase the magnesium level should be based on the severity of the deficiency.
• For mild magnesium deficiency, the usual adult dose is 1 g (8.12 mEq of magnesium) injected IM every six hours for four doses.
• For severe hypomagnesemia, the dose can be as much as 250 mg (approximately 2 mEq) per kg of body weight given IM within a period of four hours if necessary. 2 2

From the Research

Magnesium Level and Dosage

• The patient's magnesium level is 1.8 mg/dL, which is considered hypomagnesemia 3.
• According to the study, asymptomatic patients with hypomagnesemia should be treated with oral magnesium supplements 3.
• However, the study does not provide a specific dosage for increasing the magnesium level.
• Another study suggests that magnesium supplementation can help prevent subclinical magnesium deficiency, but it does not provide a specific dosage for increasing the magnesium level 4.

Factors to Consider

• The patient's renal function should be established before administering any magnesium supplementation 3.
• The patient's symptoms and medical history should be taken into account when determining the dosage and treatment plan.
• The study highlights the importance of measuring fractional excretion of magnesium and urinary calcium-creatinine ratio to determine the likely cause of hypomagnesemia 3.

Treatment Options

• Oral magnesium supplements are recommended for asymptomatic patients with hypomagnesemia 3.
• Parenteral magnesium should be reserved for symptomatic patients with severe magnesium deficiency (< 1.2 mg/dL) 3.
• The dosage and treatment plan should be individualized based on the patient's specific needs and medical history.