A nurse is assessing a client with severe pre-eclampsia who is receiving magnesium sulfate infusion.

Which finding should alert the nurse to suspect magnesium toxicity?

The correct answer is A and B. A. Serum magnesium level of 8 mg/dL

This statement is correct because a serum magnesium level of 8 mg/dL (6.6 mmol/L) is within the therapeutic range for eclampsia treatment, which is 3.5 to 7 mEq/L (4.2 to 8.4 mg/dL) according to some sources, or 1.5 to 3.5 mmol/L according to others.A serum magnesium level above 8 mEq/L (10 mmol/L) can cause areflexia, respiratory paralysis, and cardiac arrest.

B. Serum calcium level of 7 mg/dL

This statement is correct because a serum calcium level of 7 mg/dL (1.75 mmol/L) is below the normal range of 8.5 to 10.2 mg/dL (2.12 to 2.55 mmol/L), which indicates hypocalcemia.Hypocalcemia is a common side effect of magnesium sulfate therapy, as magnesium competes with calcium for binding sites on plasma proteins and cell membranes, and also inhibits the release of parathyroid hormone.

C. Serum creatinine level of 1.2 mg/dL

This statement is wrong because a serum creatinine level of 1.2 mg/dL (106 umol/L) is within the normal range of 0.6 to 1.3 mg/dL (53 to 115 umol/L) for women.Serum creatinine level reflects kidney function, and renal impairment can affect the clearance of magnesium sulfate and increase the risk of toxicity.

D. Serum potassium level of 3.8 mEq/L

This statement is wrong because a serum potassium level of 3.8 mEq/L (3.8 mmol/L) is within the normal range of 3.5 to 5 mEq/L (3.5 to 5 mmol/L) for adults.Serum potassium level reflects electrolyte balance, and hypokalemia or hyperkalemia can affect cardiac function and muscle contraction.

E. Serum sodium level of 140 mEq/L

This statement is wrong because a serum sodium level of 140 mEq/L (140 mmol/L) is within the normal range of 135 to 145 mEq/L (135 to 145 mmol/L) for adults.Serum sodium level reflects fluid balance, and hyponatremia or hypernatremia can affect brain function and blood pressure.

Magnesium sulfate therapy is used to prevent seizures in women with preeclampsia, a complication of pregnancy characterized by high blood pressure and organ dysfunction.Seizures are a sign of eclampsia, a severe form of preeclampsia that can be life-threatening.

Therefore, if the therapy is successful, the woman should not have any seizures.

Choice B.Absence of proteinuria is wrong because proteinuria, or excess protein in urine, is a possible sign of preeclampsia, not eclampsia.

Proteinuria may not disappear even after magnesium sulfate therapy.

Choice C.Absence of edema is wrong because edema, or swelling, is a common symptom of pregnancy and may not be related to preeclampsia or eclampsia.

Edema may not disappear even after magnesium sulfate therapy.

Choice D.Absence of headache is wrong because headache is a symptom of preeclampsia, not eclampsia.

Headache may not disappear even after magnesium sulfate therapy.

Normal ranges for blood pressure are below 140/90 mm Hg and for protein in urine are below 300 mg per 24 hours.