IV Magnesium

Clinical Importance of Magnesium

Hypomagnesemia (low magnesium levels) is a common condition in intensive care units. According to research, hypomagnesemia is seen in 20% to 65% of intensive care patients. This rate highlights the strong relationship between hypomagnesemia and the clinical outcomes of intensive care patients. In particular, complications such as systemic inflammatory response syndrome (SIRS), sepsis, organ dysfunction and cardiac arrhythmias are directly related to magnesium deficiency.

The role of magnesium in intensive care patients is not limited to problems caused by deficiency. Serum magnesium levels have been shown to be closely related to morbidity and mortality. For example, patients with low magnesium levels have an increased risk of developing cardiac complications because magnesium regulates potassium channels in cardiac cells and prevents arrhythmias. It stabilizes the heart rhythm by preventing the uncontrolled release of potassium out of the cell.

Magnesium therapy has a long history in the medical world. Intravenous use of magnesium sulfate, especially in the treatment of preeclampsia and eclampsia, has been a standard for years. In addition, magnesium use is also common in the following clinical situations:

• Perioperative and Postoperative Period: Magnesium is used for perioperative analgesia and prevention of postoperative shivering. It also plays a supportive role in anesthesia management with its muscle relaxant effect during surgical procedures.

• Cardiac Arrhythmias: Magnesium is a life-saving treatment option, especially in serious arrhythmic conditions such as torsades de pointes due to hypomagnesemia.

• Acute Myocardial Infarction: Magnesium therapy may be effective in stabilizing the heart muscle and reducing reperfusion injuries.

• Asthma Attacks: Magnesium is used intravenously in the treatment of severe asthma attacks due to its bronchodilator effects.

• Tetanus Treatment: It relieves tetanus symptoms by regulating neuromuscular activity.

Physiological and Molecular Effects of Magnesium

Role as a Calcium Antagonist: Magnesium regulates the calcium balance within the cell. It keeps intracellular calcium levels under control by suppressing calcium release from the sarcoplasmic reticulum. This mechanism affects smooth muscle tone in cells and helps prevent conditions such as hypertension, bronchospasm, and coronary artery spasm.

Neuromuscular Transmission and Cardiac Effects: Magnesium plays a role in the activation of the Na+/K+-ATPase enzyme. This enzyme provides neuromuscular stability by regulating the flow of sodium and potassium across the cell membrane. In case of deficiency, neuromuscular complications such as muscle spasms, irritability, and hyperreflexia may occur. At the cardiac level, magnesium stabilizes the heart rhythm by blocking the escape of potassium from the cell and reduces the risk of arrhythmia.

Importance in Energy Metabolism: During energy production, the ATP molecule becomes active by complexing with magnesium. Magnesium also plays a fundamental role in protein and nucleic acid synthesis. Mitochondrial function and stabilization of the cytoskeleton are also magnesium-dependent processes.

Magnesium Metabolism

Absorption and Distribution: Magnesium is absorbed in the gastrointestinal tract. Absorption occurs through passive diffusion, especially from the ileum and jejunum. Recent studies have shown that magnesium is also taken up by active transcellular absorption mechanisms. The amount of magnesium in the diet affects the rate of absorption; even a diet with a low magnesium content can maintain body balance thanks to the reabsorption capacity of the kidneys.

The kidneys are the primary regulator of magnesium homeostasis. 70% of the filtered magnesium is reabsorbed from the loop of Henle by passive paracellular mechanisms, while 5% is excreted in the urine. The kidneys' capacity to regulate magnesium excretion helps prevent fluctuations in serum magnesium levels.

Balancing Factors: Factors affecting magnesium homeostasis include acidosis, ischemia, insulin administration, and intravenous solutions containing glucose. For example, renal magnesium excretion increases during hypermagnesemia, while the kidneys reabsorb magnesium to a maximum extent during hypomagnesemia.

Assessment of Magnesium Status

Serum Magnesium Measurements: Serum magnesium levels represent only 0.3% of the total body magnesium stores and are generally considered normal at 1.7-2.3 mg/dL. However, this measurement does not reflect ionized magnesium, the biologically active form of magnesium. Therefore, ionized magnesium measurement provides more accurate information for clinical evaluation.

Intraerythrocyte Magnesium Measurements: Intraerythrocyte magnesium levels are used to more accurately assess cellular magnesium status. In our clinic, intravenous magnesium treatment is planned based on the data obtained with these measurements.

Clinical Applications of IV Magnesium Therapy

Absorption and Distribution: Magnesium is absorbed in the gastrointestinal tract. Absorption occurs through passive diffusion, especially from the ileum and jejunum. Recent studies have shown that magnesium is also taken up by active transcellular absorption mechanisms. The amount of magnesium in the diet affects the rate of absorption; even a diet with a low magnesium content can maintain body balance thanks to the reabsorption capacity of the kidneys.

The kidneys are the primary regulator of magnesium homeostasis. 70% of the filtered magnesium is reabsorbed from the loop of Henle by passive paracellular mechanisms, while 5% is excreted in the urine. The kidneys' capacity to regulate magnesium excretion helps prevent fluctuations in serum magnesium levels.

Balancing Factors: Factors affecting magnesium homeostasis include acidosis, ischemia, insulin administration, and intravenous solutions containing glucose. For example, renal magnesium excretion increases during hypermagnesemia, while the kidneys reabsorb magnesium to a maximum extent during hypomagnesemia.

Questions Frequently Asked by Our Patients About IV Magnesium

What is IV magnesium and what is it used for?

IV magnesium refers to magnesium sulfate or other magnesium salts administered intravenously. It supports many biochemical processes, ranging from energy metabolism to muscle relaxation. It is widely used in conditions such as hypomagnesemia, preeclampsia, asthma attacks, cardiac arrhythmias, and perioperative analgesia.

In which situations is IV magnesium used?

IV magnesium can be administered in the following conditions:

• Treatment of hypomagnesemia

• Management of preeclampsia and eclampsia

• Control of cardiac arrhythmias (e.g., torsades de pointes)

• Bronchodilator effect in asthma attacks

• Perioperative and postoperative muscle relaxation

• Supportive treatment in acute myocardial infarction

• Prevention of neuromuscular hyperactivity

Is IV magnesium safe?

IV magnesium treatment is generally safe. However, side effects such as hypotension, bradycardia, and respiratory depression can occur. These effects can be managed through careful dose adjustment and close patient monitoring.

How is IV magnesium administered?

IV magnesium is usually given via an infusion pump depending on the patient’s magnesium levels and clinical condition. The dose and duration are individualized. In urgent cases, a bolus dose may be administered over a short period.

What are the side effects of IV magnesium therapy?

Although rare, side effects may include:

• Hypotension (low blood pressure)

• Bradycardia (slow heart rate)

• Nausea or vomiting

• Respiratory depression

• Skin flushing or a warm sensation

Monitoring the dosage and infusion rate helps prevent these reactions.

How long does IV magnesium treatment last?

The treatment duration depends on the clinical need. In acute conditions (e.g., preeclampsia, arrhythmia), treatment may be completed in a few hours. In chronic hypomagnesemia or ongoing losses, several days of treatment may be required.

Who should not receive IV magnesium?

IV magnesium should be used cautiously or avoided in the following cases:

• Patients with kidney failure

• Individuals with hypermagnesemia (high magnesium levels)

• Patients with myasthenia gravis (a neuromuscular disorder)

• Individuals with severe hypotension

A doctor will assess the risks before initiating therapy.

How is the dosage of IV magnesium determined?

The dose depends on the patient’s serum magnesium level, age, weight, and clinical status. In treating hypomagnesemia, 1–2 grams of magnesium sulfate are commonly administered via slow IV infusion. Higher doses may be needed in cardiac emergencies.

What should be monitored during IV magnesium therapy?

During therapy, the following should be carefully monitored:

• Serum magnesium levels

• Blood pressure, heart rate, and respiratory function

• Signs of side effects (e.g., hypotension, bradycardia)

• Kidney function, as magnesium is excreted through the kidneys

What should be done after IV magnesium treatment?

After treatment, the patient's overall status should be reassessed. Magnesium levels are checked to confirm normalization. Additional treatment may be planned to manage the underlying cause of magnesium deficiency (e.g., poor diet or renal loss).