Which symptom indicates Magnesium toxicity?

Magnesium toxicity typically leads to a significant decrease in neuromuscular activity, which is evidenced by the absence of deep tendon reflexes. As magnesium levels rise excessively, the body experiences a depression of the central nervous system and neuromuscular transmission, resulting in diminished reflex responses. In the context of magnesium's role in the body, it is a critical cofactor in many enzymatic reactions and a natural calcium channel blocker. When magnesium reaches toxic levels, it disrupts normal muscle contractility and reduces neuromuscular excitability, causing reflexes—such as deep tendon reflexes—to be diminished or absent.

Other symptoms of magnesium toxicity may include respiratory muscle paralysis, hypotension, bradycardia, and altered mental status. However, the hallmark sign remains the lack of deep tendon reflexes, making this the most direct indicator of magnesium toxicity. Understanding this symptom is essential for critical care paramedics when assessing patients with suspected electrolyte imbalances or those receiving magnesium therapy, ensuring timely intervention if toxicity is identified.