Therapeutic serum level of magnesium in patients with severe pre-eclampsia treated with magnesium sulfate

ABSTRACT

Serum levels of magnesium were determined in 20 healthy nonpregnant females, 20 healthy normotensive pregnant females at term and 20 pregnant females at term with severe preeclampsia. All the preeclamptic patients received a low dosage intramuscular regimen of magnesium sulfate [MgSO[4]] and the serum levels of magnesium were determined again after 24 hours. There was no difference in the baseline values of serum magnesium inthe 3 studied groups. A 6 g loading dose of MgSO[4][3 g I.V. and 3 g I.M.] followed by 3 g/4 hr. I.M. caused maternal serum magnesium concentrations to rise by about 50% from the baseline value of 1.8 mEq/L [2.2 mg/dl] to 2.7 mEq/L [3.3 mg/dl] [P < 0.0001]. Oxytocin used to augment or induce labor in 7 preeclamptic patients had no effect on the serum level of magnesium. The efficiency of our regimen in preventing seizures in cases of severe preeclampsia suggests that the therapeutic level of serum mangesium required to prevent convulsions in preeclampsia may not be as high as previously defined by other investigators. The possibility that a higher dose of MgSO[4], to achieve a higher therapeutic serum level of magnesium, is needed to treat and prevent further seizures in eclampsia is present. Thus, MgSO[4] regimen should be different in the two conditions of similar etiology but with variable severity