Understanding Malnutrition Severity
Malnutrition encompasses a range of conditions resulting from deficiencies, excesses, or imbalances in a person's intake of energy or nutrients. This guide focuses on undernutrition, specifically on assessing the severity of protein-energy malnutrition, which can manifest as wasting or stunting. The assessment is not a single test but a comprehensive evaluation that combines clinical, physical, and biochemical data. The severity is typically categorized as moderate or severe, guiding the intensity and setting of medical intervention required.
Assessing Malnutrition in Adults: The GLIM Criteria
The Global Leadership Initiative on Malnutrition (GLIM) provides a standardized, two-step approach for diagnosing and classifying malnutrition severity in adults. This consensus framework requires the presence of at least one phenotypic and one etiologic criterion. After initial screening identifies an 'at risk' status, a full assessment is performed.
Phenotypic Criteria (Physical Attributes) for Severity Grading
- Weight loss: Measured as a percentage of body weight over a specified period. Greater weight loss indicates more severe malnutrition.
- Low Body Mass Index (BMI): Specific cutoffs are used depending on age and ethnicity. Lower BMI indicates higher severity.
- Reduced muscle mass: Assessed using validated body composition measures like bioelectrical impedance, or alternative anthropometric measures such as calf circumference.
Etiologic Criteria (Underlying Causes)
- Reduced food intake or assimilation: Occurs due to conditions like anorexia, dysphagia, or gastrointestinal disorders.
- Inflammation or disease burden: The presence of acute disease, chronic illness, or injury that increases metabolic demand.
Assessing Malnutrition in Children: WHO Guidelines
The World Health Organization (WHO) provides specific diagnostic criteria for children, particularly those aged 6–60 months, to determine the severity of acute malnutrition, also known as wasting. These are often measured and expressed in standard deviations (Z-scores) from a reference population.
Key Indicators for Childhood Malnutrition Severity
- Weight-for-height Z-score (WHZ): Compares a child's weight to a reference of a healthy child of the same height. A score of < -3 SD indicates severe acute malnutrition (SAM), while a score between -2 and -3 SD indicates moderate acute malnutrition (MAM).
- Mid-Upper Arm Circumference (MUAC): A simple and effective tool, especially in community settings. A MUAC < 115 mm signifies SAM.
- Bilateral Pitting Edema: The presence of swelling on both feet is an independent clinical sign of severe malnutrition (kwashiorkor), regardless of other measurements.
Role of Biochemical Markers
While not primary diagnostic tools for overall severity, certain biochemical markers can provide supportive evidence and help monitor nutritional status, particularly in hospitalized patients or those with underlying disease. However, their interpretation must be cautious as they can be influenced by inflammation and liver function.
- Albumin: Traditionally used, but has a long half-life and is significantly affected by inflammation, making it a poor indicator of acute changes.
- Prealbumin (Transthyretin): With a shorter half-life, it reflects recent changes more accurately but is still influenced by inflammation.
- C-reactive protein (CRP): A marker of inflammation. Measuring CRP alongside other indicators helps contextualize protein levels and distinguish between malnutrition and inflammatory states.
Comparison of Assessment Criteria for Severity
| Assessment Category | Adults (GLIM Criteria) | Children (WHO Guidelines) |
|---|---|---|
| Anthropometric Indicators | Weight Loss (%), Low BMI, Reduced Muscle Mass | Weight-for-Height Z-score (WHZ), Mid-Upper Arm Circumference (MUAC) |
| Clinical Signs | Physical examination for fat/muscle loss, functional status | Bilateral Pitting Edema, Visible severe wasting |
| Severity Grading | Stage 1 (Moderate): 5–10% weight loss in 6 months OR BMI < 20 (if <70) / <22 (if ≥70). | Moderate Acute Malnutrition (MAM): WHZ between -2 and -3 SD. |
| Severe Grading | Stage 2 (Severe): >10% weight loss in 6 months OR BMI < 18.5 (if <70) / <20 (if ≥70). | Severe Acute Malnutrition (SAM): WHZ < -3 SD, MUAC < 115mm, or bilateral edema. |
| Etiologic Component | Mandatory for diagnosis (reduced intake, inflammation). | Considered in patient history and comorbidities. |
Conclusion
Determining the severity of malnutrition is a multi-faceted process that relies on established, evidence-based criteria. For adults, the GLIM framework systematically combines phenotypic and etiologic factors to grade severity, while for children, WHO guidelines use anthropometric measurements like WHZ and MUAC, along with clinical signs like edema, to categorize severity into moderate or severe. Accurate assessment is critical for tailoring nutritional interventions and improving patient outcomes. Consistent application of these diagnostic tools ensures that at-risk individuals receive appropriate and timely care, mitigating the serious and lasting consequences of malnutrition. For more in-depth information on diagnosis and management protocols, refer to official medical and nutritional guidelines, such as those provided by the Canadian Malnutrition Task Force (CMTF).
