From the Research
Switching from magnesium oxide 400 mg twice daily to magnesium glycinate is recommended for a patient with malabsorption and hypomagnesemia. Magnesium glycinate is a better choice because it has superior bioavailability compared to magnesium oxide, especially in patients with malabsorption issues 1. For this patient, a typical starting dose would be 200-400 mg of elemental magnesium from magnesium glycinate daily, divided into 2-3 doses. Since magnesium glycinate contains about 14% elemental magnesium (compared to oxide's 60%), the actual supplement dose would be higher - approximately 1400-2800 mg of magnesium glycinate daily. This form is bound to the amino acid glycine, which uses different absorption pathways than oxide, bypassing some of the intestinal absorption issues. Additionally, magnesium glycinate causes less gastrointestinal side effects like diarrhea, which is particularly important in malabsorption patients. Some studies suggest that magnesium deficiency can be caused by various factors, including gastrointestinal disorders, renal disorders, and certain medications 2, 3, 4. However, the most recent and highest quality study 1 supports the use of magnesium glycinate in patients with refractory hypomagnesemia. Monitor serum magnesium levels every 1-2 weeks initially, then monthly once levels stabilize, aiming for a target range of 1.8-2.4 mg/dL. Remind the patient to take the supplement with food and consider vitamin D supplementation if deficient, as this can improve magnesium absorption. It is also important to note that severe hypomagnesemia can have serious clinical manifestations, including neuromuscular irritability, cardiac arrhythmias, and increased sensitivity to digoxin 2, 5. Therefore, prompt treatment and monitoring of serum magnesium levels are crucial in patients with hypomagnesemia. Key points to consider when treating hypomagnesemia include:
- Using magnesium glycinate instead of magnesium oxide due to its superior bioavailability
- Starting with a dose of 200-400 mg of elemental magnesium daily, divided into 2-3 doses
- Monitoring serum magnesium levels regularly to adjust the dose as needed
- Considering vitamin D supplementation if deficient to improve magnesium absorption
- Being aware of the potential clinical manifestations of severe hypomagnesemia and the importance of prompt treatment.