Magnesium toxicity
| Hypermagnesemia | |
|---|---|
 |
|
| Magnesium | |
| Classification and external resources | |
| Specialty | endocrinology, disorder of magnesium metabolism |
| ICD-10 | E83.4 |
| ICD-9-CM | 275.2 |
| DiseasesDB | 6259 |
| eMedicine | med/3383 emerg/262 ped/1080 |
Hypermagnesemia is an electrolyte disturbance in which there is a high level of magnesium in the blood. It is defined as a level greater than 1.1 mmol/L. Symptoms include weakness, confusion, decreased breathing rate, and cardiac arrest.
Hypermagnesemia can occur in kidney failure and those who are given magnesium salts or who take drugs that contain magnesium (e.g. some antacids and laxatives). It is usually concurrent with other electrolyte disturbances such as a low blood calcium and/or high blood potassium level. Specific electrocardiogram (ECG) changes may be present.
Treatment when levels are very high include calcium chloride, intravenous normal saline with furosemide, and hemodialysis.
Hypermagnesemia occurs rarely because the kidney is very effective in excreting excess magnesium.
Abnormal heart rhythms and asystole are possible complications of hypermagnesemia related to the heart. Magnesium acts as a physiologic calcium blocker, which results in electrical conduction abnormalities within the heart.
Clinical consequences related to serum concentration:
Note that the therapeutic range for the prevention of the pre-eclampsic uterine contractions is: 4.0-7.0 mEq/L. As per Lu and Nightingale, serum Mg2+ concentrations associated with maternal toxicity (also neonate depression - hypotonia and low Apgar scores) are:
Results from a longitudinal study with end-stage renal disease suggest that hypermagnesemia may retard the development of arterial calcifications in end-stage renal disease. Significantly lower values of carotid intima-media thickness and aortic pulse wave velocity values, which are surrogate markers for vascular calcification, were observed in chronic kidney disease patients with high serum magnesium levels (0.90–1.32 mmol/L or 2.18–3.21 mg/dL) indicating a lower arteriosclerotic burden associated with a lower risk of cardiovascular events and mortality. Consequently, people with CKD with mildly elevated magnesium levels could have a survival advantage over those with lower magnesium levels.
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