Hypermagnesemia

Source: Wikipedia, the free encyclopedia.
Hypermagnesemia
Other namesMagnesium toxicity
intravenous normal saline with furosemide, hemodialysis[1]
FrequencyUncommon[3]

Hypermagnesemia is an

low blood pressure and cardiac arrest.[1][5]

It is typically caused by

electrocardiogram (ECG) changes may be present.[1]

Treatment involves stopping the magnesium a person is getting.

intravenous normal saline with furosemide, and hemodialysis.[1] Hypermagnesemia is uncommon.[3] Rates among hospitalized patients in renal failure may be as high as 10%.[2]

Signs and symptoms

Symptoms include

abnormal heart rhythms and asystole, dizziness, and sleepiness
.

Abnormal heart rhythms and asystole are possible complications of hypermagnesemia related to the heart.

electrical conduction system of the heart
.

Consequences related to serum concentration:[9]: 281 

At magnesium levels about 4.5 mEq/L the stretch reflex is lost and with over 6.5 mEq/L respiratory failure may be observed. On ECG hypermagnesemia is mainly manifested by prolongation of PR and QRS intervals, T wave changes and AV block.[9]: 281 

The therapeutic range for the prevention of the pre-eclamptic uterine contractions is: 4.0–7.0 mEq/L.[10] As per Lu and Nightingale,[11] serum magnesium concentrations associated with maternal toxicity (also neonate depression, hypotonia and low Apgar scores) are:

  • 7.0–10.0 mEq/L – Loss of patellar reflex
  • 10.0-13.0 mEq/L – Respiratory depression
  • 15.0-25.0 mEq/L – Altered atrioventricular conduction and (further) complete heart block
  • >25.0 mEq/L – Cardiac arrest

Complications

Severe hypermagnesemia (levels greater than 12 mg/dL) can lead to cardiovascular complications (hypotension and arrhythmias) and neurological disorder (confusion and lethargy). Higher values of serum magnesium (exceeding 15 mg/dL) can induce cardiac arrest and coma. [4]

Causes

Magnesium status depends on three organs: uptake in the

kidneys. Hypermagnesemia is therefore often due to problems in these organs, mostly the intestine or kidney.[12]

Predisposing conditions

  • Hemolysis, magnesium concentration in red blood cells is approximately three times greater than in serum, therefore hemolysis can increase plasma magnesium. Hypermagnesemia is expected only in massive hemolysis.
  • creatinine clearance
    falls below 30 ml/min. However, hypermagnesemia is not a prominent feature of chronic kidney disease unless magnesium intake is increased.
  • Magnesium toxicity
    from emergency pre-eclampsia treatment during labor and delivery.
  • Other conditions that can predispose to mild hypermagnesemia are diabetic ketoacidosis, adrenal insufficiency, hypothyroidism, hyperparathyroidism, and lithium intoxication.

Metabolism

For a detailed description of magnesium

hypomagnesemia
.

Diagnosis

Hypermagnesemia is diagnosed by measuring the concentration of magnesium in the blood. Concentrations of magnesium greater than 1.1 mmol/L are considered diagnostic.[1]

Treatment

People with normal

kidney function (glomerular filtration rate
(GFR) over 60 ml/min) and mild asymptomatic hypermagnesemia require no treatment except for the removal of all sources of exogenous magnesium. One must consider that the half-time of elimination of magnesium is approximately 28 hours.

In more severe cases, close monitoring of the ECG, blood pressure, and neuromuscular function and early treatment are necessary:

Intravenous

antagonized
by calcium.

Severe clinical conditions require increasing renal magnesium excretion through:

Intravenous

hypocalcemia
, thus possibly worsening the symptoms and signs of hypermagnesemia.

The use of diuretics must be associated with infusions of saline solutions to avoid further

electrolyte disturbances (e.g., hypokalemia) and metabolic alkalosis
. The clinician must perform serial measurements of calcium and magnesium. In association with electrolytic correction, it is often necessary to support cardiorespiratory activity. As a consequence, the treatment of this electrolyte disorder can frequently require intensive care unit (ICU) admission.

Particular clinical conditions require a specific approach. For instance, during the management of

deep tendon reflexes are absent, or the respiratory rate is below 12 breaths/minute. A 10% calcium gluconate or chloride solution can serve as an antidote.[4]

Prognosis

The prognosis of hypermagnesemia depends on magnesium values and on the clinical condition that induced hypermagnesemia. Values that are not excessively high (mild hypermagnesemia) and in the absence of triggering and aggravating conditions (e.g., chronic kidney disease) are benign conditions. On the contrary, high values (severe hypermagnesemia) expose the patient to high risks and high mortality.[4]

Epidemiology

Hypermagnesemia is an uncommon electrolyte disorder. It occurs in approximately 10 to 15% of hospitalized patients with renal failure. Furthermore, epidemiological data suggest that there is a significant prevalence of high levels of serum magnesium in selected healthy populations. For instance the overall prevalence of hypermagnesemia was 3.0%, especially in males in Iran. High magnesium concentrations were typical in people with cardiovascular disease, and 2.3 mg/dL or higher values were associated with worse hospital mortality.[4]

References

  1. ^
    PMID 20956045
    .
  2. ^
    ISBN 9780323511995
    .
  3. ^ a b c d e f g "Hypermagnesemia". Merck Manuals Professional Edition. Retrieved 28 October 2018.
  4. ^
    PMID 31747218. This article incorporates text available under the CC BY 4.0
    license.
  5. ^
    ISBN 978-0323081276
    .
  6. PMID 24470089.{{cite book}}: CS1 maint: multiple names: authors list (link
    )
  7. PMID 6709029
    .
  8. PMID 10661484
    .
  9. ^
    OCLC 1007160054.{{cite book}}: CS1 maint: location missing publisher (link) CS1 maint: others (link
    )
  10. PMID 13238166
    .
  11. S2CID 45298797
    .
  12. PMID 26069819
    .

External links

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