Loss of deep tendon reflexes occurs at which magnesium level range?

Loss of deep tendon reflexes occurs at which magnesium level range?

• A. 5-8 mg/dL
• B. 5-10 mg/dL
• C. 8-12 mg/dL
• D. 20-35 mg/dL

Answer: (C)

Magnesium excess dampens neuromuscular transmission, so deep tendon reflexes are among the first clinical signs to diminish as levels rise. As the drug accumulates, its effect at the neuromuscular junction—reducing calcium-dependent release of acetylcholine—progresses from subtle hyporeflexia to complete loss of reflexes. This loss signals a moderate-to-high level of toxicity, occurring before more life-threatening problems like respiratory depression or cardiovascular instability. In practice, especially with MgSO4 therapy for preeclampsia, the appearance (and then loss) of reflexes is a crucial warning to reassess the infusion, monitor respirations, and check the magnesium level to prevent progression to severe toxicity.

Magnesium excess dampens neuromuscular transmission, so deep tendon reflexes are among the first clinical signs to diminish as levels rise. As the drug accumulates, its effect at the neuromuscular junction—reducing calcium-dependent release of acetylcholine—progresses from subtle hyporeflexia to complete loss of reflexes. This loss signals a moderate-to-high level of toxicity, occurring before more life-threatening problems like respiratory depression or cardiovascular instability. In practice, especially with MgSO4 therapy for preeclampsia, the appearance (and then loss) of reflexes is a crucial warning to reassess the infusion, monitor respirations, and check the magnesium level to prevent progression to severe toxicity.