Standard Anthropometric Measures
Anthropometric measurements are a primary method for diagnosing severe acute malnutrition (SAM), especially in children. These measurements provide a standardized way to assess a child's nutritional status relative to a healthy reference population, typically using the WHO Child Growth Standards.
Weight-for-Height Z-Score (WHZ)
The Weight-for-Height Z-score (WHZ) is a statistical measure that compares a child's weight to a reference median for children of the same height and gender. A child with a WHZ below -3 standard deviations (SD) of the WHO median is classified as severely wasted, a form of SAM. This measure is highly specific for identifying severely malnourished individuals, as fewer than 1% of a healthy population would fall below this cutoff.
Mid-Upper Arm Circumference (MUAC)
For children aged 6 to 59 months, the Mid-Upper Arm Circumference (MUAC) is a simple and effective measure for identifying SAM, particularly in community settings. A MUAC measurement less than 115 mm indicates severe acute malnutrition. This method is especially valuable for mass screenings by community health workers due to its speed, low cost, and ease of use. Studies have shown that MUAC and WHZ identify largely different, though overlapping, populations of malnourished children, making it important to use both measures whenever possible.
Clinical Signs
Beyond anthropometry, the clinical examination of a child reveals critical signs that are also used to diagnose severe acute malnutrition.
Bilateral Pitting Oedema
Bilateral pitting oedema is a distinct clinical sign where excess fluid accumulates in the body's tissues, causing swelling, particularly in both feet. It is often a characteristic of a form of SAM known as kwashiorkor and is considered a definitive diagnosis for severe malnutrition, regardless of a child's anthropometric measurements. The assessment involves applying thumb pressure to the top of both feet for three seconds; if an indentation remains, oedema is confirmed. The severity is graded on a scale from + to +++.
General Clinical Assessment
A thorough clinical examination for SAM includes assessing for other danger signs and medical complications. These can include:
- Shock: Indicated by lethargy, unconsciousness, cold hands, and a weak pulse.
- Loss of Appetite: Tested by offering ready-to-use therapeutic food (RUTF) to see if the child will eat.
- Hypoglycaemia and Hypothermia: Abnormally low blood sugar and body temperature, respectively, are common complications.
- Infections: Children with SAM have compromised immune systems, making infections common, even without typical signs like fever.
- Severe Anaemia: Diagnosed by severe palmar pallor.
Comparison of Diagnostic Measures
| Feature | Mid-Upper Arm Circumference (MUAC) | Weight-for-Height Z-Score (WHZ) | Bilateral Pitting Oedema |
|---|---|---|---|
| Application | Rapid screening, especially in community settings | Precise assessment in clinical settings | Clinical diagnosis; confirms SAM regardless of anthropometry |
| Age Range | Typically 6–59 months | 6–59 months, per WHO standards | All ages; criterion for SAM in infants under 6 months |
| Cutoff Point for SAM | < 115 mm | < -3 standard deviations | Presence of pitting; graded + to +++ |
| Tools Needed | Simple, color-coded MUAC tape | Accurate weighing scales, stadiometer/length board, WHO charts | Manual pressure with thumbs; no special equipment |
| Type of Malnutrition | Wasting (current nutritional status) | Wasting (current nutritional status) | Kwashiorkor (fluid retention), often with wasting |
| Programmatic Use | Entry criteria for outpatient therapeutic feeding programs (OTP) | Used in facility-based and hospital care; standard for all admissions | Automatic admission to inpatient care |
| Prognostic Value | Strong predictor of mortality risk | Strong predictor of mortality risk | High mortality risk, requires urgent attention |
Additional Diagnostic Considerations
While the core measures are foundational, a comprehensive diagnosis of severe acute malnutrition includes several other tests to understand the child's overall health status. These help identify the presence of complications that influence the treatment approach, determining whether a child needs inpatient or outpatient care.
Blood Tests
Laboratory tests can reveal underlying deficiencies and infections. Important assessments include:
- Complete Blood Count (CBC): To identify anaemia and infection.
- Serum Albumin: A long-term indicator of protein status. While more useful for long-term status, it is a less sensitive short-term indicator compared to other proteins.
- Blood Glucose: To check for hypoglycaemia, a serious complication.
Appetite Test
An appetite test is a simple but critical assessment used to determine if a child with SAM can be treated as an outpatient. The child is given a small amount of Ready-to-Use Therapeutic Food (RUTF). If they readily eat it, they are considered to have a good appetite. A child with a good appetite and no complications can often be managed at home. Those who fail the test require immediate inpatient care.
The WHO and UNICEF approach to SAM
The World Health Organization (WHO) and UNICEF advocate for a combined approach to managing severe acute malnutrition. This includes using a mix of outpatient and inpatient strategies, depending on the severity and complications of the case. Community-based health workers often perform initial screening using MUAC and oedema checks, referring severe cases to health facilities for further assessment and treatment. This decentralized approach has significantly increased program coverage and reduced mortality rates.
Conclusion
Effective management of severe acute malnutrition begins with accurate and timely diagnosis. The primary measures involve using anthropometric tools like MUAC and Weight-for-Height Z-score, complemented by assessing for clinical signs such as bilateral pitting oedema. These standardized methods, endorsed by global health bodies, allow for the identification and appropriate channeling of severely malnourished individuals into life-saving treatment programs. A comprehensive approach, including clinical evaluation and an appetite test, ensures that each case receives the right level of care, whether in a hospital or at home with therapeutic foods. Correctly identifying and measuring SAM is the critical first step towards recovery and improved long-term health outcomes for at-risk populations. For more in-depth guidance, health professionals can consult manuals like the WHO's guide for managing severe malnutrition.
Additional Insights on Screening
Screening for severe acute malnutrition is a multi-step process that can begin in the community and be confirmed in a clinical setting. While different measures sometimes identify different subgroups of malnourished children, using multiple indicators provides a more complete picture of the nutritional crisis. Implementing these standard measures efficiently, particularly in settings with limited resources, is fundamental to reducing the high morbidity and mortality associated with SAM.
Screening in Different Contexts
The choice of screening tool often depends on the context and available resources. MUAC tapes are ideal for community-level screening by volunteers, while WHZ requires more specialized equipment typically found in clinics. Combining both approaches, as recommended by WHO, provides the most robust case-finding strategy, ensuring no child at risk is overlooked. This strategy is especially important in emergency situations where rapid identification and treatment are paramount.
