What is the difference between severe acute malnutrition and moderate acute malnutrition?

December 17, 2025 •

3 min read

According to the World Health Organization (WHO), over 45 million children under the age of five were affected by wasting in 2022, a sign of acute malnutrition. Understanding the specific and critical differences between severe acute malnutrition (SAM) and moderate acute malnutrition (MAM) is vital for proper diagnosis and effective treatment in addressing this global health crisis.

Quick Summary

The distinction between severe and moderate acute malnutrition is based on distinct World Health Organization criteria, including anthropometric measurements and clinical signs. Treatment protocols vary significantly depending on the severity level, directly influencing the risk of complications and mortality.

Key Points

Measurement Thresholds: Severe acute malnutrition is diagnosed with a Weight-for-Height Z-score < -3 SD or a Mid-Upper Arm Circumference (MUAC) < 115mm, while moderate acute malnutrition has thresholds of -2 to -3 SD WHZ or 115mm to <125mm MUAC.
Clinical Signs: The presence of bilateral pitting edema is a defining clinical sign of severe acute malnutrition (SAM) and is not present in moderate acute malnutrition (MAM).
Risk of Mortality: The risk of death is substantially higher and more immediate for children with severe acute malnutrition due to metabolic and immune system complications.
Treatment Setting: Complicated SAM requires inpatient medical care, while uncomplicated SAM and MAM can often be managed through outpatient, community-based programs.
Nutritional Products: Specific, ready-to-use therapeutic foods (RUTFs) are used for SAM treatment, whereas ready-to-use supplementary foods (RUSFs) are used for MAM.
Treatment Approach: Treatment for SAM involves initial stabilization and rehabilitation phases, which is more intensive than the supplementary feeding approach for MAM.
Progression Risk: Without treatment, MAM can worsen and lead to the more deadly condition of SAM.

The World Health Organization (WHO) provides clear guidelines to differentiate between severe acute malnutrition (SAM) and moderate acute malnutrition (MAM). Both indicate a deficit in nutritional status, but the severity determines the risk level and necessary medical response. Understanding these distinctions is crucial.

Diagnostic Criteria

Distinguishing between MAM and SAM primarily relies on diagnostic indicators like anthropometric measurements and clinical signs. Tools such as Mid-Upper Arm Circumference (MUAC) and Weight-for-Height Z-score (WHZ) are used to compare a child's status to WHO standards.

Moderate Acute Malnutrition (MAM)

WHZ: Between -2 and -3 standard deviations (SD) of the median.
MUAC: For children aged 6 to 59 months, between 115 mm and less than 125 mm.
Clinical Signs: No bilateral pitting edema.

Severe Acute Malnutrition (SAM)

WHZ: Less than -3 standard deviations (SD) of the median.
MUAC: Less than 115 mm in children 6 to 59 months.
Bilateral Pitting Edema: Presence of swelling in both feet is a definitive sign of SAM.

Health Risks

The severity of malnutrition directly correlates with health risks. While MAM increases infection risk, SAM poses a much higher and immediate threat of death due to severe medical complications.

MAM Risks: Increased vulnerability to infections and potential progression to SAM if untreated.
SAM Risks: High risk of severe metabolic issues, infections, hypoglycemia, hypothermia, dehydration, and electrolyte imbalances. The immune system is severely weakened.

Treatment Approaches

Treatment protocols differ based on severity and risk.

Moderate Acute Malnutrition Treatment

Location: Often managed in outpatient, community settings.
Method: Supplementary feeding using Ready-to-Use Supplementary Food (RUSFs) and nutrition education.
Goal: Prevent progression to SAM and promote growth.

Severe Acute Malnutrition Treatment

Location: Uncomplicated SAM can be treated as outpatients with RUTF. Complicated cases require hospitalization.
Method: Inpatient treatment involves stabilization and rehabilitation, including managing infections, rehydration, and refeeding with therapeutic milks and RUTF.
Goal: Stabilize, restore health, and achieve weight gain.

Comparison Table: MAM vs. SAM


Feature	Moderate Acute Malnutrition (MAM)	Severe Acute Malnutrition (SAM)
Diagnostic Criteria	- WHZ between -2 and -3 SD. - MUAC between 115mm and <125mm (children 6-59 months).	- WHZ < -3 SD. - MUAC < 115mm. - Bilateral pitting edema.
Clinical Status	Generally alert, good appetite.	Poor appetite, lethargy, or other medical issues possible.
Health Risks	Increased infection vulnerability, risk of progressing to SAM.	Significantly higher mortality risk, severe complications.
Treatment Setting	Often outpatient, community-based.	Inpatient for complicated cases; outpatient for uncomplicated.
Treatment Products	Ready-to-Use Supplementary Food (RUSF).	Ready-to-Use Therapeutic Food (RUTF) and therapeutic milks.
Treatment Duration	Typically shorter, focused on supplementary feeding.	Longer, includes stabilization and rehabilitation.

The Urgency of Correct Diagnosis

Accurate differentiation between SAM and MAM is vital due to the severe consequences of misdiagnosis. Treating SAM as MAM without proper medical oversight significantly increases mortality risk. Bilateral pitting edema is a clear indicator of severe malnutrition requiring immediate, specialized care. Community-based management programs effectively use these criteria for treatment pathways.

Conclusion

SAM and MAM are distinct stages of acute malnutrition, requiring different diagnostic approaches, posing different risks, and demanding specific treatment protocols. The difference between severe acute malnutrition and moderate acute malnutrition is a critical distinction for effective intervention. Accurate assessment using tools like MUAC and WHZ, alongside clinical evaluation, is essential for providing appropriate, life-saving care and improving child survival rates globally.

What is the difference between severe acute malnutrition and moderate acute malnutrition? Key takeaways

Diagnostic Markers: The primary difference lies in diagnostic criteria, with SAM having more severe anthropometric indicators (lower MUAC and WHZ) and the presence of bilateral pitting edema.
Health Risks: SAM is associated with a significantly higher and more immediate risk of mortality and severe medical complications compared to MAM, which increases susceptibility to infections.
Treatment Protocols: Treatment for SAM can require specialized inpatient care for complications, whereas MAM is typically managed in outpatient community programs with supplemental feeding.
Treatment Products: Different nutritional products are used for treatment; RUTFs for SAM and RUSFs for MAM, tailored to the specific needs of the child.
Severity and Urgency: The clinical state determines urgency; SAM is a medical emergency requiring rapid intervention, while MAM requires consistent supplementary feeding to prevent progression to a more severe state.

Frequently Asked Questions

The primary difference is the severity based on WHO-defined criteria. SAM is the most extreme form, characterized by a WHZ < -3, MUAC < 115mm, or the presence of bilateral edema, while MAM is a less severe form with moderate anthropometric deficits.

Bilateral pitting edema is swelling in both feet that leaves a persistent indentation when pressed. Its presence is a definitive clinical sign of severe acute malnutrition (kwashiorkor), regardless of other measurements, and indicates an immediate need for inpatient medical care due to higher mortality risk.

No, treatment protocols differ significantly. SAM requires a more intensive approach, potentially including hospitalization for complications, while MAM is typically managed in outpatient settings with supplemental feeding.

Yes, without effective treatment, a child with moderate acute malnutrition can deteriorate and progress to the more life-threatening condition of severe acute malnutrition.

Ready-to-Use Therapeutic Food (RUTF), a nutrient-dense peanut paste, is the cornerstone of SAM treatment in community settings. In hospital, therapeutic milks like F-75 and F-100 are used for stabilization before transitioning to RUTF.

Common and dangerous complications of SAM include hypoglycemia, hypothermia, severe infections, dehydration, and electrolyte imbalances. These issues require immediate medical attention and are why complicated SAM cases are hospitalized.

MUAC is a simple yet effective tool for screening and identifying acute malnutrition, especially in community settings. A MUAC below 115mm indicates SAM, and a MUAC between 115mm and <125mm indicates MAM for children aged 6 to 59 months.