Laboratory Studies
Electrolytes, including potassium, magnesium, and calcium levels [8, 9]
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A test for ionized magnesium is clinically available. However, it is used most often for monitoring magnesium infusions. The serum magnesium level is often used as an initial study in the ED.
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Elevation in magnesium level is usually not found as an isolated electrolyte abnormality.
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Hyperkalemia and hypercalcemia are often present concurrently.
BUN and creatinine levels
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Obtain renal function tests and calculate creatinine clearance to assess the ability of the kidney to excrete magnesium.
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Serum magnesium levels rise when creatinine clearance is less than 30 mL/min.
Check serum creatine phosphokinase (CPK) level or urine myoglobin level in patients in whom rhabdomyolysis is suspected.
Arterial blood gases (ABG) may reveal a respiratory acidosis.
Thyroid function tests
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Hypothyroidism is a rare cause of hypermagnesemia.
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Check these tests in the absence of any other good explanation.
Other Tests
An ECG and cardiac monitor may show prolongation of the PR interval or intraventricular conduction delay, which are nonspecific findings.
The ECG findings may reflect other electrolyte abnormalities such as hyperkalemia.
