Muscle paralysis and respiratory difficulty occur at which magnesium level range?

Muscle paralysis and respiratory difficulty occur at which magnesium level range?

• A. 5-8 mg/dL
• B. 5-10 mg/dL
• C. 15-17 mg/dL
• D. 20-35 mg/dL

Answer: (C)

Muscle paralysis and respiratory difficulty happen when magnesium levels become extremely high, because magnesium suppresses neuromuscular transmission. At very elevated concentrations, the normal signaling at the neuromuscular junction is profoundly dampened, so skeletal muscles can no longer respond and the respiratory muscles, including the diaphragm, become weak or fail. This is the severe toxicity range of hypermagnesemia, well above the normal and therapeutic levels. For context, normal magnesium is roughly 1.5–2.5 mg/dL, and the therapeutic range used with magnesium sulfate in obstetric settings is higher but still requires careful monitoring; as levels climb toward the extreme end, signs progress from diminished reflexes and weakness to respiratory depression, paralysis, and potential cardiac compromise. If this level is suspected, stop magnesium, monitor closely, and be prepared to support respiration, with calcium gluconate as an antidote if needed.

Muscle paralysis and respiratory difficulty happen when magnesium levels become extremely high, because magnesium suppresses neuromuscular transmission. At very elevated concentrations, the normal signaling at the neuromuscular junction is profoundly dampened, so skeletal muscles can no longer respond and the respiratory muscles, including the diaphragm, become weak or fail. This is the severe toxicity range of hypermagnesemia, well above the normal and therapeutic levels. For context, normal magnesium is roughly 1.5–2.5 mg/dL, and the therapeutic range used with magnesium sulfate in obstetric settings is higher but still requires careful monitoring; as levels climb toward the extreme end, signs progress from diminished reflexes and weakness to respiratory depression, paralysis, and potential cardiac compromise. If this level is suspected, stop magnesium, monitor closely, and be prepared to support respiration, with calcium gluconate as an antidote if needed.