Pediatric Hypermagnesemia Clinical Presentation
- Author: Robert J Ferry Jr, MD; Chief Editor: Stephen Kemp, MD, PhD more...
History
- Symptoms of hypermagnesemia are nonspecific at lower levels (2-4 mEq/L) and may include the following:
- Nausea
- Vomiting
- Flushing
- Lethargy
- Weakness
- Dizziness
- Higher levels may lead to a depressed sensorium, and cardiopulmonary arrest may occur at extreme levels (>10-15 mEq/L).
Physical
- Hypermagnesemia results in loss of deep-tendon reflexes at levels of 4-6 mEq/L. At magnesium levels of more than 5 mEq/L, CNS depression, which may range from drowsiness to coma, begins. Although concentrations of magnesium of more than 10 mEq/L lead to respiratory depression in adults, this may occur at much lower levels in the newborn.
- Hypermagnesemia has a negative effect on heart rate.[7] Beginning with magnesium serum levels of 4.5 mEq/L, depression of sinoatrial node activity and atrial fibrillation may occur. Higher magnesium levels increase the P-R interval, widen the QRS complex, and can cause intraventricular conduction delays. Serum magnesium concentrations greater than 15 mEq/L can lead to complete heart block and asystole.
- At varying levels (5-8 mEq/L), hypermagnesemia may produce vasodepression of vascular smooth muscle leading to systemic hypotension.
- Although the absolute serum levels are important, the rate of rise is even more significant. For instance, a fast rise in serum level can produce cardiovascular symptoms more readily than can a slower rise in serum levels.
Causes
- Major predisposing factors for the development of hypermagnesemia include the following:
- Renal failure (acute or chronic)
- Iatrogenic over administration of magnesium (eg, antacids, cathartics)
- Neonates born to mothers treated with magnesium sulfate for eclampsia
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