How to determine malnutrition severity?

Worldwide, nearly half of deaths among children under five years of age are linked to undernutrition. Accurately assessing and determining malnutrition severity is crucial for identifying at-risk individuals and implementing effective treatment plans, but it requires a multi-faceted approach involving clinical, physical, and laboratory evaluations.

Quick Summary

This article outlines the standard methods for diagnosing and classifying the severity of malnutrition in both adults and children. It details the criteria used in screening tools and comprehensive assessments, including physical examination, anthropometric measurements, and biochemical markers, for accurate diagnosis and tailored intervention strategies.

Key Points

• GLIM Criteria: Diagnosing malnutrition in adults involves using the GLIM framework, which requires assessing at least one phenotypic criterion (weight loss, low BMI, or reduced muscle mass) and one etiologic criterion (reduced intake or inflammation).

• Pediatric Indicators: For children, severity is determined using anthropometric measures like weight-for-height (wasting), height-for-age (stunting), and weight-for-age (underweight), typically assessed using WHO growth standards.

• MUAC Screening: A quick and simple tool, the Mid-Upper Arm Circumference (MUAC) tape, is used for children aged 6 to 59 months to classify the severity of acute malnutrition based on color-coded thresholds.

• Screening Tools: Initial screening can be done with validated tools like the Malnutrition Universal Screening Tool (MUST) for general adults or the Mini Nutritional Assessment (MNA) for the elderly to identify risk before a full assessment.

• Severity Grading: Malnutrition severity is typically graded as moderate or severe based on the degree of the identified deficit in phenotypic criteria, which directs the intensity of the treatment plan.

• Biochemical Markers: Laboratory tests measuring visceral proteins (like albumin and prealbumin) and micronutrient levels provide supporting data for a malnutrition diagnosis, though they are not used in isolation.

• Early Intervention: Early and accurate assessment is crucial because malnourished individuals are more prone to infection and have slower wound healing, emphasizing the need for timely intervention.

Standardized Criteria for Adults: GLIM

The Global Leadership Initiative on Malnutrition (GLIM) criteria provide a consensus-based approach for diagnosing and grading malnutrition severity in adults. The diagnosis requires at least one phenotypic criterion and one etiologic criterion. Phenotypic criteria include unintentional weight loss, low body mass index (BMI), and reduced muscle mass. Etiologic criteria include reduced food intake or assimilation and disease burden (inflammation). The severity of malnutrition is then graded as moderate or severe based on the degree of phenotypic deficit.

The GLIM Diagnostic Framework

• Phenotypic Criteria: These measure the physical and compositional changes in the body.
  • Unintentional Weight Loss: A loss of 5–10% over six months (or 10–20% over a longer period) indicates moderate malnutrition, while a loss greater than 10% in six months (or greater than 20% in a longer period) indicates severe malnutrition.
  • Low BMI: For individuals under 70, a BMI under 20 kg/m² indicates moderate malnutrition, and under 18.5 kg/m² indicates severe. For those aged 70 or older, the cutoffs are <22 kg/m² and <20 kg/m², respectively.
  • Reduced Muscle Mass: Assessed through physical examination or body composition measurement techniques like DEXA. A mild to moderate deficit is considered moderate malnutrition, while a severe deficit indicates severe malnutrition.
• Etiologic Criteria: These determine the underlying cause of nutritional imbalance.
  • Reduced Food Intake or Assimilation: This includes consuming ≤50% of the estimated energy requirement for more than one week, or having chronic gastrointestinal conditions that impair nutrient absorption.
  • Inflammation: Indicated by an acute disease, injury, or a chronic disease with associated inflammation.

Using Screening Tools like MUST and MNA

Before a full GLIM assessment, patients can be screened using tools like the Malnutrition Universal Screening Tool (MUST) or the Mini Nutritional Assessment (MNA).

• MUST: A five-step tool used to identify adults at risk of malnutrition. It scores patients based on BMI, recent unintentional weight loss, and the effect of acute disease.
• MNA-Short Form: Specifically for older adults (65+), this tool uses a short questionnaire to evaluate factors like food intake, weight loss, mobility, and stress to identify risk.

Specialized Assessment for Children

Diagnosing malnutrition in children requires different criteria that account for their rapid growth and development. Anthropometric measurements are key, typically using World Health Organization (WHO) growth standards to calculate Z-scores.

Indicators for Pediatric Malnutrition Severity

• Wasting (Low weight-for-height): This indicates acute malnutrition, often due to recent illness or insufficient food. Severe acute malnutrition (SAM) is defined as a weight-for-height Z-score (WHZ) of less than -3 standard deviations, or a mid-upper arm circumference (MUAC) less than 115mm.
• Stunting (Low height-for-age): This is the result of chronic or recurrent undernutrition. It holds children back from reaching their full physical and cognitive potential.
• Underweight (Low weight-for-age): A child who is underweight may be wasted, stunted, or both.

The Mid-Upper Arm Circumference (MUAC) Test

The MUAC test is a simple and effective screening tool, especially useful in resource-limited settings. For children aged 6 to 59 months, a color-coded tape measures the upper arm's circumference to quickly determine nutritional status.

• Green: 12.5 cm or more, indicating normal nutritional status.
• Yellow: 11 cm to 12.5 cm, indicating moderate acute malnutrition.
• Red: Less than 11 cm, indicating severe acute malnutrition.

Comparison of Malnutrition Assessment Tools

Feature	GLIM (Adults)	MUAC (Children)	MNA-SF (Elderly)
Focus	Multi-criteria diagnosis and severity grading.	Rapid screening and classification of acute malnutrition.	Screening for malnutrition risk.
Key Measurements	Weight loss, BMI, muscle mass, food intake, inflammation.	Mid-upper arm circumference (MUAC), sometimes weight-for-height.	Food intake, weight loss, mobility, stress, neuropsychology, BMI or calf circumference.
Assessment Type	Comprehensive, requires clinical judgment and data.	Quick, physical measurement with color-coded results.	Questionnaire-based screening tool.
Outputs	Diagnosis (moderate or severe) and underlying etiology.	Color-coded risk status (Normal, Moderate, Severe).	Score-based classification (Normal, At-Risk, Malnourished).
Strengths	Standardized, evidence-based for clinical settings.	Fast, simple, and effective in field conditions.	Tailored to the specific needs and risk factors of older adults.

Conclusion

Determining malnutrition severity is a critical step in providing appropriate nutritional care and preventing serious health complications. The approach varies depending on the patient's age, from the standardized GLIM framework for adults to specific anthropometric indicators like MUAC for children. The use of validated screening tools and a comprehensive assessment that includes physical examination, dietary history, and biochemical markers is essential for accurate diagnosis and grading. A clear and timely diagnosis allows healthcare professionals to develop a targeted management plan that can significantly improve patient outcomes. For example, studies have shown that patients with a proper diagnosis of malnutrition often have better outcomes when receiving tailored nutrition interventions.

References

• PMC. Characteristics and Outcomes of Adult Inpatients with Malnutrition. https://pmc.ncbi.nlm.nih.gov/articles/PMC6021228/
• WHO. Fact sheets - Malnutrition. https://www.who.int/news-room/fact-sheets/detail/malnutrition

Frequently Asked Questions

What is the difference between moderate and severe malnutrition in adults?

According to the GLIM criteria, moderate malnutrition involves a weight loss of 5–10% in six months or a BMI between 18.5–20 kg/m² for those under 70. Severe malnutrition involves a weight loss greater than 10% in six months or a BMI below 18.5 kg/m² for the same age group.

How is malnutrition severity determined in children?

In children, malnutrition severity is often determined using anthropometric Z-scores based on WHO growth standards, such as weight-for-height (wasting) or height-for-age (stunting). MUAC is also used for quick, field-based screening.

What does a low BMI indicate in the assessment of malnutrition?

A low BMI (<18.5 kg/m² for adults under 70) is one of the key phenotypic criteria for diagnosing and grading severe malnutrition under the GLIM framework. Age-specific cutoffs are used for elderly adults and children.

Why is intentional weight loss not a criterion for malnutrition?

Only unintentional weight loss is a criterion for malnutrition, as it signifies a loss of body mass due to an underlying health problem, disease, or lack of proper nutrients. Intentional weight loss is a controlled process and does not necessarily indicate malnutrition.

Are blood tests alone sufficient to diagnose malnutrition?

No, blood tests alone are not sufficient. While they can provide supportive evidence of specific nutrient deficiencies, levels of visceral proteins like albumin can be affected by other factors such as inflammation, hydration, and disease states. Comprehensive assessments combine multiple criteria.

Can an overweight person be malnourished?

Yes, it is possible to be overweight or obese and still be malnourished. This occurs when a person consumes excessive calories but lacks a balanced intake of essential micronutrients, leading to deficiencies in vitamins and minerals.

What are the common symptoms of severe malnutrition?

Symptoms of severe malnutrition can include extreme muscle wasting, low body weight, bilateral pitting edema, low body temperature, fatigue, irritability, and a weakened immune system leading to frequent infections.