Electrolyte Imbalances in Severe Acute Malnutrition: A Comprehensive Guide

October 29, 2025 •

4 min read

Studies have shown that over 93% of children with severe acute malnutrition (SAM) experience some form of electrolyte imbalance, often complicating treatment and increasing mortality risk. This issue, if not properly managed, can lead to fatal cardiac and neurological complications, making a thorough understanding of electrolyte imbalances in severe acute malnutrition essential for effective treatment.

Quick Summary

This guide details the major electrolyte abnormalities—including hypokalemia, hyponatremia, hypomagnesemia, and hypocalcemia—associated with severe acute malnutrition. It explains the causes, symptoms, and critical importance of careful monitoring and management during nutritional rehabilitation to prevent life-threatening complications like refeeding syndrome.

Key Points

Hypokalemia is Highly Prevalent: Studies show that a majority of children with SAM have hypokalemia (low potassium), which can lead to life-threatening cardiac arrhythmias and muscle weakness.
Hyponatremia Often Masks Sodium Excess: In edematous malnutrition, low serum sodium (hyponatremia) is common but is a dilutional effect, often masking a total body sodium excess and requiring cautious fluid management.
Refeeding Syndrome is a Major Risk: When nutritional support is introduced too quickly, it can cause severe shifts in phosphate, potassium, and magnesium, leading to fatal complications like cardiac failure.
Potassium, Magnesium, and Phosphate are Deficient: Total body stores of potassium, magnesium, and phosphate are severely depleted in SAM, requiring careful and consistent supplementation, regardless of initial blood test results.
Treatment Must Be Cautious and Gradual: The management of electrolyte imbalances involves slow, controlled feeding with special formulas (e.g., F-75, ReSoMal) to avoid worsening the patient's condition and to safely restore balance.
Intravenous Fluid Use is Limited: IV fluid is generally restricted to treating shock due to the high risk of fluid overload and heart failure in severely malnourished patients.

Understanding Severe Acute Malnutrition and Electrolyte Disturbances

Severe Acute Malnutrition (SAM) is a complex medical condition defined by a significant deficit in nutritional intake, leading to severe body wasting, low weight-for-height, or bilateral pitting edema. Electrolyte disturbances are a nearly universal feature of SAM, impacting the entire body's metabolic processes and increasing the risk of death if not addressed promptly. The body's intricate balance of electrolytes—minerals like sodium, potassium, and magnesium—is crucial for nerve function, muscle contraction, and maintaining proper fluid balance. In SAM, these systems are disrupted by depleted stores and metabolic shifts.

The primary electrolyte problems encountered in SAM include hypokalemia (low potassium), hyponatremia (low sodium), hypomagnesemia (low magnesium), and hypophosphatemia (low phosphate), the last being a critical feature of refeeding syndrome. These imbalances do not always correlate with a patient's serum (blood) electrolyte levels, as significant total body deficits can be present despite seemingly normal or slightly low serum values. Therefore, aggressive treatment is necessary, regardless of the initial serum test results, especially during the critical phase of nutritional rehabilitation.

Key Electrolyte Imbalances in SAM

Hypokalemia

This is one of the most prevalent and dangerous electrolyte imbalances in children with SAM, often found in a high percentage of patients. Potassium is the main intracellular cation and plays a vital role in cellular functions, nerve impulses, and muscle contractions. The total body potassium is significantly reduced in SAM due to a combination of factors:

Low Dietary Intake: Inadequate consumption of food leads to a direct lack of potassium.
Loss of Intracellular Content: As cells lose protein and muscle mass, potassium shifts out of the cells, resulting in a net loss from the body.
Diarrhea: Many children with SAM also suffer from chronic diarrhea, which exacerbates potassium loss.

Symptoms of severe hypokalemia include muscle weakness, lethargy, abdominal distention (due to paralytic ileus), and, most dangerously, potentially fatal cardiac arrhythmias.

Hyponatremia

Low serum sodium levels (hyponatremia) are frequently observed, particularly in edematous forms of SAM (kwashiorkor). While serum sodium may appear low, this often masks a total body sodium excess due to fluid retention. Mechanisms contributing to hyponatremia include:

Dilutional Effect: Excess total body water dilutes the sodium concentration in the blood.
Increased Hormone Levels: Elevated levels of antidiuretic hormone (ADH) and the renin-angiotensin-aldosterone system (RAAS) lead to water and sodium retention, respectively.
Intracellular Shift: Loss of intracellular potassium causes a shift of sodium into the cells.

Hypomagnesemia and Hypocalcemia

Magnesium and calcium deficiencies are also common and are closely linked to overall malnutrition. Magnesium is critical for numerous enzymatic reactions, and its deficiency can lead to neuromuscular and cardiac problems. Hypocalcemia, which is low serum calcium, can be exacerbated by low magnesium and cause seizures in young children. The depletion of these electrolytes often happens concurrently, and correcting one (e.g., calcium) without addressing the underlying magnesium deficiency may be ineffective.

Refeeding Syndrome

Refeeding syndrome is a major complication that can occur when severely malnourished patients are given nutritional support too rapidly. The sudden shift from a catabolic (breaking down tissue) state to an anabolic (building tissue) state triggers insulin release, which drives glucose, potassium, magnesium, and phosphate into the cells. This rapid electrolyte shift can cause severe hypophosphatemia, hypokalemia, and hypomagnesemia, leading to:

Cardiovascular collapse
Respiratory failure
Neurological symptoms, including confusion and seizures

Treatment and Management

Effective management of electrolyte imbalances in SAM requires a cautious and systematic approach, guided by specific protocols like those developed by the World Health Organization (WHO). Treatment occurs in two main phases: stabilization and rehabilitation.

Comparison of Treatment Phases for Electrolyte Management


Feature	Stabilization Phase	Rehabilitation Phase
Timing	First 1-2 days of hospital admission.	After the patient is clinically stable, lasting several weeks.
Goal	Correct immediate life-threatening imbalances and treat infections.	Restore nutritional status and correct underlying deficiencies.
Nutritional Formula	Special low-lactose, low-sodium F-75 formula.	Higher-calorie F-100 formula or Ready-to-Use Therapeutic Food (RUTF).
Fluid Management	Cautious, slow rehydration with a specialized solution (ReSoMal). IV fluids only for shock.	Higher fluid intake to support catch-up growth.
Electrolyte Correction	Initial electrolyte correction is critical. Potassium, magnesium, and phosphate are added to all formulas.	Continued electrolyte supplementation in feeding and daily monitoring.
Refeeding Syndrome	The highest risk period; requires vigilant monitoring of serum electrolytes.	Risk decreases but remains a consideration throughout recovery.

Key Management Strategies

Slow, Cautious Feeding: Begin with small, frequent feeds of low-sodium, high-potassium formula (F-75) to prevent overwhelming the system and triggering refeeding syndrome.
Aggressive Electrolyte Supplementation: Provide potassium, magnesium, and phosphate as part of the initial nutritional therapy. Serum levels may appear deceptively normal, so supplementation is given based on total body deficit rather than just serum levels.
Careful Rehydration: Use a specific oral rehydration solution (ReSoMal) with a lower sodium concentration to address dehydration without exacerbating fluid overload. Intravenous fluids are only used in cases of shock due to the risk of fluid overload and cardiac complications.
Continuous Monitoring: Closely monitor clinical signs and serum electrolyte levels, especially during the first few days of refeeding, as levels can drop rapidly.
Treating Associated Conditions: Address underlying infections, as these can worsen the electrolyte imbalance.

Conclusion

Electrolyte imbalances in severe acute malnutrition are not just a consequence of poor nutrition; they are a central and life-threatening aspect of the disease. Hypokalemia, hyponatremia, and other deficiencies pose significant risks, especially cardiac complications, which demand careful management. The refeeding period is particularly dangerous due to the risk of refeeding syndrome, emphasizing the need for a gradual and controlled nutritional rehabilitation plan. Medical professionals treating SAM must be vigilant in monitoring and proactively supplementing electrolytes, using special formulations and cautious rehydration protocols to prevent high mortality rates. Through adherence to established guidelines, these critical imbalances can be corrected, paving the way for recovery and growth in affected individuals. Link: https://www.who.int/publications/i/item/9241546755

Frequently Asked Questions

Hypokalemia, or low potassium, is one of the most frequently observed and dangerous electrolyte imbalances in SAM patients.

In edematous SAM, hyponatremia (low serum sodium) is primarily a dilutional effect. The body retains excess water due to hormonal changes, which dilutes the total body sodium, creating a low serum concentration despite potential total body sodium overload.

Refeeding syndrome is a potentially fatal metabolic disturbance that occurs when nutritional support is given too rapidly to a severely malnourished person. It causes a sudden and rapid shift of fluids and electrolytes, particularly phosphate, potassium, and magnesium, leading to heart, respiratory, and neurological failure.

Rehydration in SAM requires a cautious approach using a special low-sodium oral rehydration solution (ReSoMal). Intravenous fluids should be used sparingly and only for advanced shock, as there is a significant risk of fluid overload leading to heart failure.

Yes. Initial blood tests may not accurately reflect the total body deficit of electrolytes, especially potassium and magnesium. The true extent of depletion is often higher than what serum levels indicate, requiring proactive and aggressive supplementation.

Common symptoms of severe hypokalemia include muscle weakness, lethargy, abdominal distension due to poor bowel function (paralytic ileus), and abnormal heart rhythms (cardiac arrhythmias).

Magnesium is vital for correcting other electrolyte imbalances, such as hypokalemia and hypocalcemia. Treating magnesium deficiency is a necessary step before other electrolytes can be effectively corrected, as it is a cofactor in many metabolic processes.