Severe acute malnutrition (SAM) is a life-threatening form of malnutrition caused by a severe deficiency in energy and nutrients, leading to significant physiological changes. SAM is classified based on three primary diagnostic criteria established by the World Health Organization (WHO): low mid-upper arm circumference (MUAC), very low weight-for-height (or length) z-score, and the presence of bilateral pitting edema. Early identification is paramount for effective treatment and improved survival rates, particularly in young children and vulnerable adults.
WHO Diagnostic Criteria for Severe Acute Malnutrition
The most reliable way to diagnose SAM is through standardized anthropometric and clinical assessments. A diagnosis is confirmed if any one of the following three criteria is met:
- Low Mid-Upper Arm Circumference (MUAC): This simple and effective screening tool uses a non-stretch measuring tape to assess muscle wasting. For children aged 6–59 months, a MUAC of less than 115 mm is a key indicator of SAM and high mortality risk. MUAC can also be used in adults, though cut-offs vary.
- Very Low Weight-for-Height/Length (WHZ): For children aged 6–59 months, a WHZ that falls below $-3$ standard deviations ($SD$) of the WHO Child Growth Standards median indicates severe wasting. This measure requires accurate weight and height/length measurements by trained personnel and is a 'gold standard' for diagnosing wasting.
- Bilateral Pitting Edema: The presence of bilateral pitting edema is a definitive clinical sign of SAM, regardless of MUAC or WHZ measurements. This fluid retention is typically observed as swelling in both feet but can also extend to the hands and face in severe cases. To test for pitting edema, gentle pressure is applied with a thumb on the top of both feet for a few seconds; if a dent remains after the pressure is released, it is considered positive.
Differentiating Types of SAM: Marasmus vs. Kwashiorkor
Historically, SAM was categorized into marasmus (severe wasting) and kwashiorkor (edema). While treatment protocols are now similar, distinguishing between the two can provide valuable clinical insight.
Clinical Signs and Symptoms
Recognizing Physical Symptoms in Children and Adults Identifying SAM involves a careful physical examination for specific signs and symptoms, as many classic signs of infection, such as fever, may be absent in severely malnourished individuals.
- General Signs:
- Unintentional and significant weight loss.
- Low energy levels, fatigue, and weakness.
- Apathy, irritability, and behavioral changes, especially in children.
- Increased susceptibility to infections due to a compromised immune system.
- Slow wound healing.
- Specific Physical Findings:
- Skin: Dry, peeling, and hyperpigmented skin, often with sores or raw areas that resemble severe burns in kwashiorkor.
- Hair: Thin, sparse, or brittle hair that changes color and is easily pulled out.
- Eyes: Signs of vitamin A deficiency, such as dry conjunctiva or corneal ulceration.
- Digestive Issues: Persistent diarrhea, abdominal distention, and poor appetite.
- Circulatory Problems: Low heart rate and blood pressure, potentially leading to shock.
Assessment Procedures for Diagnosis
For an accurate diagnosis, healthcare providers follow a systematic approach that combines a physical exam with anthropometric measurements. Key steps include:
- Anthropometric Measurements: For children, this includes measuring MUAC and plotting weight-for-height on WHO growth charts. For adults, the Malnutrition Universal Screening Tool (MUST), which uses Body Mass Index (BMI), can be employed.
- Clinical Assessment: A full physical examination is performed to check for medical complications like infection, dehydration, and signs of vitamin deficiencies. An appetite test, offering Ready-to-Use Therapeutic Food (RUTF), helps determine if the individual can be managed as an outpatient.
- Laboratory Tests: In hospitalized patients, laboratory tests may be conducted to check for hypoglycemia, electrolyte imbalances, and severe anemia.
Example of MUAC Measurement To perform a MUAC measurement for a child (6-59 months):
- Have the child's left arm bent at the elbow.
- Locate the mid-point between the shoulder and elbow using a standard tape measure.
- Wrap the MUAC tape around the arm at this mid-point.
- Ensure the tape is in contact with the skin but not tight enough to pinch.
- Read the measurement, with a red zone indicating SAM.
Conclusion
Early and accurate identification of severe acute malnutrition is a critical step in providing life-saving treatment. The WHO-recommended criteria, which include using MUAC, WHZ, and assessing for bilateral pitting edema, provide a standardized approach for clinicians and community health workers. Beyond these core indicators, a comprehensive clinical evaluation for underlying complications and the distinction between marasmus and kwashiorkor are crucial for effective management. By systematically applying these identification methods, it is possible to diagnose SAM early and initiate the necessary therapeutic feeding and medical interventions to prevent further deterioration and death.
Learn more about WHO guidelines for identifying and managing severe acute malnutrition in children by visiting their website.
