Official Diagnostic Criteria for Severe Acute Malnutrition
The World Health Organization (WHO) defines the criteria for severe acute malnutrition (SAM) primarily through a combination of three independent indicators for children between 6 and 59 months old. A child can be diagnosed with SAM if they meet any one of these criteria. These standards are critical for guiding admission to therapeutic feeding programs, whether community-based or inpatient.
Anthropometric Indicators
The assessment of a child's physical measurements is the first step in diagnosing SAM. The two main anthropometric indicators are weight-for-height and mid-upper arm circumference (MUAC).
- Weight-for-Height Z-score (WHZ): A child is diagnosed with severe wasting, a form of SAM, if their weight-for-height is less than -3 standard deviations (SD) of the WHO Child Growth Standards median. This measurement is particularly effective for identifying severely underweight children for their length or height and is considered a gold standard in clinical settings.
- Mid-Upper Arm Circumference (MUAC): A MUAC of less than 115 mm is another key diagnostic criterion for SAM in children aged 6 to 59 months. This is a simple, quick, and effective screening tool, especially useful for community health workers and during emergency situations. A low MUAC indicates significant muscle mass loss and a high risk of death. The MUAC measurement is particularly effective at identifying younger children with SAM, who might be missed by WHZ criteria alone.
Clinical Indicator
The presence of bilateral pitting oedema is a definitive clinical sign of SAM, specifically associated with kwashiorkor.
- Bilateral Pitting Oedema: This is defined as swelling in both feet and ankles. The 'pitting' is confirmed by applying gentle pressure with a thumb on the top of the child's foot for three seconds. If a dent or 'pit' remains after the pressure is released, oedema is present. The severity is often graded from + (mild) to +++ (severe), with severe oedema indicating a higher risk of mortality. Oedema is caused by severe protein deficiency, leading to fluid retention.
Medical Complications and Management
Beyond the core diagnostic criteria, a full clinical assessment is necessary to determine the presence of medical complications, which dictates the appropriate course of management. Children with complicated SAM—characterized by medical issues, poor appetite, or severe oedema (+++)—require inpatient care in a stabilization center. Conversely, children with uncomplicated SAM can be managed on an outpatient basis.
Essential steps in the initial assessment include checking for signs of:
- Hypoglycemia: Low blood sugar, which is a common risk in malnourished children.
- Hypothermia: A low body temperature, which can signal serious infection.
- Infection: Signs of infection may be masked in severely malnourished children, so broad-spectrum antibiotics are often administered.
- Dehydration: Careful rehydration is necessary, often using specially formulated solutions like ReSoMal, as standard ORS can be harmful.
Comparison of Kwashiorkor and Marasmus
Severe acute malnutrition can manifest in different forms, notably kwashiorkor and marasmus. While their treatment approaches are largely similar, understanding their distinct characteristics helps illustrate the multifaceted nature of SAM.
| Feature | Kwashiorkor | Marasmus |
|---|---|---|
| Primary Cause | Severe protein deficiency, often with adequate caloric intake. | Deficiency of all macronutrients (protein, carbohydrates, fats), leading to overall energy starvation. |
| Physical Appearance | Bloated or swollen body, particularly the feet, ankles, face, and abdomen, due to oedema. | Severely emaciated, with a "skin and bones" appearance and visible ribs due to muscle and fat wasting. |
| Oedema | Present (bilateral pitting oedema). | Absent. |
| Subcutaneous Fat | Some may be retained, masking the true extent of muscle wasting. | Severely depleted or absent, resulting in loose, wrinkled skin. |
| Fatty Liver | Often enlarged due to impaired protein synthesis and fat transport. | The liver is typically not enlarged. |
| Skin and Hair | Changes may include dry, flaky skin, rash, and loss of hair pigment. | Skin appears dry, loose, and wrinkled, but without the flaky rash seen in kwashiorkor. |
| Common Age Group | Often seen in children aged 6 months to 3 years, after weaning. | More common in younger infants, typically under 1 year of age. |
| Appetite | Can have a poor or absent appetite. | May have a relatively normal or even voracious appetite initially. |
Importance of Early Identification
The criteria for severe acute malnutrition are not merely academic; they are life-saving tools. Early identification in the community allows for timely intervention, preventing the progression to life-threatening complications. Community-based management strategies, such as the use of Ready-to-Use Therapeutic Foods (RUTFs), have proven highly effective for treating uncomplicated SAM, bringing care closer to home for millions.
Conclusion
The established criteria for severe acute malnutrition—specifically, a weight-for-height z-score of less than -3 SD, a mid-upper arm circumference (MUAC) under 115 mm (for children 6–59 months), or the presence of bilateral pitting oedema—are critical tools for diagnosis. These criteria, endorsed by the WHO, facilitate early identification and guide the appropriate management strategy, whether at a community level or requiring inpatient care. Understanding the distinct features of clinical manifestations like marasmus and kwashiorkor, alongside routine screening for other medical complications, is essential for effective treatment and reducing child mortality associated with malnutrition. The move towards decentralized, community-based approaches has made it possible to address SAM more proactively, but adherence to these clear diagnostic guidelines remains the foundation of effective intervention. For more comprehensive information on treatment guidelines, consult official World Health Organization documents.
Additional Considerations
Special Cases: Infants Under 6 Months
While the primary criteria apply to children aged 6 to 59 months, SAM in infants under 6 months is defined by different standards. For this age group, diagnosis relies on a weight-for-length z-score of less than -3 SD and/or the presence of bilateral pitting oedema. Feeding difficulties and a failure to gain weight also indicate SAM in this group. Management often involves more intensive support and careful feeding observation.
Social and Environmental Factors
While this article focuses on the clinical and anthropometric criteria, it is important to acknowledge that the development of SAM is also heavily influenced by social and environmental factors. These include poverty, food insecurity, poor sanitation, and infectious diseases. The most effective strategies for preventing and managing SAM integrate clinical treatment with broader public health interventions that address these root causes.
Monitoring and Evaluation
Monitoring a child's progress is integral to treatment. Weight gain and resolution of oedema are key indicators of recovery. However, it's also important to monitor for signs of over-rehydration, especially when treating oedematous malnutrition, as this can lead to heart failure. Guidelines outline specific steps for monitoring during both the stabilization and rehabilitation phases of care.
