For a client receiving IV magnesium sulfate for severe preeclampsia, which assessment finding would alert to hypermagnesemia?

For a client receiving IV magnesium sulfate for severe preeclampsia, which assessment finding would alert to hypermagnesemia?

• A. Tachycardia
• B. Decreased deep tendon reflexes
• C. Hyperglycemia
• D. Elevated blood pressure

Answer: (B)

Magnesium sulfate helps prevent seizures in severe preeclampsia by depressing neuromuscular transmission. As magnesium levels rise, the nervous system and muscles become more inhibited. The earliest sign of hypermagnesemia is a change in neuromuscular function, most reliably seen as a decrease or loss of deep tendon reflexes. This reflects the drug’s effect on the peripheral nerves and muscles before more dangerous symptoms develop. Other toxic signs to watch for—such as hypotension, bradycardia, and respiratory depression—occur as levels rise further, but decreased reflexes are the key early alert. Hyperglycemia and elevated blood pressure are not typical indicators of magnesium toxicity; in fact, blood pressure may drop with toxicity due to vasodilation. In practice, monitor reflexes, respiratory rate, oxygenation, and blood pressure closely during IV magnesium. If reflexes become diminished or absent, reassess the regimen, consider holding magnesium sulfate, and have calcium gluconate available as an antidote if toxicity is suspected.

Magnesium sulfate helps prevent seizures in severe preeclampsia by depressing neuromuscular transmission. As magnesium levels rise, the nervous system and muscles become more inhibited. The earliest sign of hypermagnesemia is a change in neuromuscular function, most reliably seen as a decrease or loss of deep tendon reflexes. This reflects the drug’s effect on the peripheral nerves and muscles before more dangerous symptoms develop.

Other toxic signs to watch for—such as hypotension, bradycardia, and respiratory depression—occur as levels rise further, but decreased reflexes are the key early alert. Hyperglycemia and elevated blood pressure are not typical indicators of magnesium toxicity; in fact, blood pressure may drop with toxicity due to vasodilation.

In practice, monitor reflexes, respiratory rate, oxygenation, and blood pressure closely during IV magnesium. If reflexes become diminished or absent, reassess the regimen, consider holding magnesium sulfate, and have calcium gluconate available as an antidote if toxicity is suspected.