Table 1.

Empirical recommendations for Mg replacement according to serum levels

1. Correction of Mg deficit:

1a. Severe HypoMg (<1 mEq/l) with life-threatening symptoms:

Administer 16 mEq IV for 1 min of magnesium sulfate.

Then, 4 ml of magnesium sulfate 500 mg (4 mEq/ml) in 250 ml of 0.9 % saline solution or 5 % dextrose

Continue with IV dose as per regime as described in the next section.

1b. Severe HypoMg <1 mEq/l with no life-threatening symptoms:

First day: 1 mEq/kg and then 0.5 mEq/kg/day for 2–5 days until correction.

Administer magnesium sulfate 500 mg (4 mEq/ml) in 250 ml of 0.9 % saline solution or 5 % dextrose at administration intervals of 1.5 h and speed ≤1.2 mEq/min. Increase infusion time to 4 h if undesirable effects appear such as hypotension.

1c. Hypomagnesemia >1 mEq/l and <1.5 mEq/l without symptoms:

Start with oral route; diarrhea is a limiting adverse effect, but infrequent at a dose of <80 mEq/24 h and also reduced if dose is increased gradually and if Mg is administered after meals. No oral form is indicated for replacement of Mg and it is usually used as antacids or laxatives.

Magnesium oxide tablets: start with 400 mg twice a day with meals and increase dose every week by 400 mg/day. Maximum dose: 400 mg/4 times a day (80 mEq/24 h); there is also oral magnesium chloride and magnesium lactate. If using magnesium oxide oral suspension: 5 ml/4 times a day with meals (56 mEq/24 h).

Consider 6–12 months of treatment to replace Mg deficit.

2. Maintenance for oral correction.

Used to prevent recurrence of deficit. Oral Mg is prescribed in doses of approximately 48 mEq/24 h, divided into various intakes with meals.

Adapted from Crosby et al. [16].