Magnesium (Normal range 1.5 – 2.6 mg/dl)
In our pharmacy, MgSO4 comes as premix that is 1g in 50ml of Normal Saline and 2g in 100ml of Normal Saline. If you need 4 grams, they pharmacy will mix 4g in 100ml. Sometimes, if the physician wants, they can also prepare the MgSO4 in D5W.
| Serum Mg level | Replace with | Recheck |
| less than 1 mg/dL | Magnesium Sulfate 4-8g IV over 12-24h | Next AM |
| 1-1.5 mg/dL | Magnesium Sulfate 2-4g IV over 4-12h | Next AM |
| 1.6-1.9 mg/dL | Magnesium Sulfate 1-2g IV over 1-2h, or Magnesium oxide 400 mg by mouth every 4 hours x 2 doses |
Next AM |
MgSO4 = Magnesium sulfate.
Another approach is:
If Magnesium level is 1.7 to 2, give 2 grams of MgSO4 IV.
If Magnesium level is 1.3 to 1.7 give 4 grams of MgSO4 IV.
Note, PO doses large enough to work will cause diarrhea in patients with a significantly low magnesium level.