Hypermagnesemia causes, nursing assessment, and treatment

The kidneys are responsible for filtering magnesium from the blood and excreting it through the urine. When the kidneys are not functioning properly, magnesium levels can build up in the blood, leading to hypermagnesemia. This can occur in patients with chronic kidney disease or acute kidney injury.

Antacids or laxatives with magnesium in them should be avoided in patients with End-stage Renal disease (ESRD) as it can cause a significant buildup of magnesium in the blood.

One of the most common causes of hypermagnesemia is the excessive intake of magnesium-containing supplements or medications. This can occur when patients take high doses of magnesium supplements to treat conditions like constipation or migraines, or when they are administered magnesium-containing medications in hospital settings. This is usually combined with Kidney failure unless a massive quantity is taken in a person with normal kidney function.

Pregnant women with pre-eclampsia are often placed on an IV magnesium sulfate drip to prevent seizures. This can increase their magnesium levels between 5-7 mEq/L.

Epsom salt enemas are not recommended as they can raise the serum magnesium to dangerous levels,  even as high as 6-16 mEq/L!!

Mild hypermagnesemia (and asymptomatic) can occur in a variety of other medical conditions and scenarios including:

• Primary hyperparathyroidism
• DKA
• Tumor lysis syndrome
• Lithium
• Milk-alkali syndrome
• Adrenal insufficiency (Addison’s disease)

• Nausea and vomiting
• Flushing
• Drowsiness or lethargy
• Decreased deep tendon reflexes

• Somnolence
• Hypocalcemia
• Absent Deep tendon reflexes
• Hypotension
• Bradycardia
• ECG changes (discussed below)

• Muscle paralysis (flaccid quadriplegia)
• Apnea and respiratory failure
• Complete heart block
• Cardiac arrest

• Temp: Normal
• HR: May be low in severe cases
• BP: May be Lower
• SPO2: Usually normal unless respiratory failure
• Respirations: usually normal

• May appear lethargic, drowsy, or weak
• May have facial flushing

• Heart rate and rhythm (any signs of arrhythmia/irregularity)
• Signs of respiratory distress, such as decreased breath sounds or respiratory rate

• Warmth of the skin (indicating vasodilation)
• Decreased grip strength
• Assess for any neuromuscular irritability (twitching, cramping, tetany)
• Abdominal tenderness (SBO or ileus from smooth muscle relaxation)
• Radial pulses (can be weak/thready if BP low)

Stopping magnesium intake will typically bring levels back down to normal pretty quickly in the absence of renal failure.

Diuretics like Loop diuretics (Lasix) or thiazide diuretics can also be used to lower magnesium levels pretty safely

IV isotonic fluids like Normal saline should be given in moderate cases of kidney failure to help restore kidney perfusion/function. Should not be given if the patient is anuric (and on dialysis).

May be required if the patient is already on dialysis or if the above measures fail. This can lower magnesium to non-toxic ranges within 2-4 hours.

Like hyperkalemia, giving IV calcium can help reverse hypermagnesemia’s neuromuscular and cardiac effects. However, this is given in a lower dose and over a longer period, with a recommended 100-200mg of elemental calcium over 5-10 minutes.

For a 10% calcium gluconate infusion, that would be 1-2mL (as opposed to 10mL given for Hyperkalemia).

Serum magnesium levels should be monitored frequently in patients with hypermagnesemia to assess the effectiveness of treatment and adjust interventions as needed. This is particularly important for patients with impaired kidney function or those receiving magnesium-containing medications, as they may be at increased risk for hypermagnesemia.

Besides magnesium levels, nurses should monitor other electrolyte levels, including calcium, potassium, and sodium, which may be affected by hypermagnesemia or its treatment. Hypocalcemia, in particular, can be a serious complication of hypermagnesemia and should be closely monitored and treated as needed.

Patients with hypermagnesemia should be monitored for signs of kidney dysfunction, particularly those with pre-existing kidney disease or impaired renal function. Creatinine and BUN should be monitored regularly (at least daily while in the hospital).

Patients with hypermagnesemia should be closely monitored for signs of cardiac arrhythmias, particularly those caused by prolonged QT intervals (see ECG changes below).

Monitor for signs of respiratory depression, particularly those with severe hypermagnesemia or impaired respiratory function. Patients may require intubation, mechanical ventilation, or other interventions to maintain adequate oxygenation and ventilation.

Patients with hypermagnesemia may experience neuromuscular irritability or depression, which can manifest as muscle twitching, cramping, or weakness. These patients are fall risks and should not be getting up without assistance!