Parameters to detect Undernutrition

Undernutrition is a condition resulting from inadequate consumption, poor accretion, or excessive loss of nutrients. It encompasses a spectrum including underweight, stunting, wasting, and micronutrient deficiencies (hidden hunger). Accurate assessment requires a multi-modal approach involving dietary, clinical, and anthropometric evaluation.

1. Dietary Assessment

Dietary history is crucial to identify the cause of undernutrition (calorie gap vs. protein gap) and assessing feeding practices.

• 24-Hour Recall: This is the most common tool used in clinical practice. The parent is asked to list all foods and drinks consumed in the last 24 hours.
  • The intake is converted into calories and proteins using standard tables and compared against the Recommended Dietary Allowance (RDA) for the age to calculate the Nutrient Gap.
• Assessment of Breastfeeding and Complementary Feeding:
  • 0–6 Months: Check for exclusive breastfeeding. If non-exclusive, assess dilution of animal milk and use of bottles.
  • 6–24 Months: This is the "weakest link" in child nutrition. Assess for timely introduction (at 6 months), frequency, consistency (thick vs. thin gruel), and dietary diversity (minimum 4 food groups).
• Food Frequency Questionnaire: Used to assess the intake of specific food groups (protective foods like vegetables/fruits) over a week to detect micronutrient deficits.

2. Anthropometric Parameters

Anthropometry is the gold standard for evaluating nutritional status.

A. Weight

• Weight-for-Age (WFA):
  • It is the most commonly used index but does not distinguish between acute and chronic malnutrition (wasting vs. stunting).
  • Underweight: Defined as WFA < -2 SD (Z-score) on WHO Growth Standards.
  • Growth Monitoring: Serial weight measurements plotted on a "Road to Health" chart are vital. A flattening or downward curve indicates growth faltering even if the single reading is within normal limits.
  • Low Weight: In IMNCI, low weight is defined as weight-for-age line below the -2 SD (yellow track on MCP card).

B. Length/Height

• Method: Recumbent length is measured for children < 2 years (or < 87 cm). Standing height is measured for children $\ge$ 2 years.
• Height-for-Age (HFA):
  • This is a measure of linear growth and indicates Stunting (Chronic Malnutrition).
  • Stunting: Defined as HFA < -2 SD. Severe stunting is < -3 SD.
  • It reflects cumulative long-term undernutrition and environmental deprivation.

C. Weight-for-Height/Length (WFH/WFL)

• Significance: This is the most specific indicator for Wasting (Acute Malnutrition).
• Advantage: It is age-independent and helps distinguish wasting from stunting.
• Wasting: Defined as WFH < -2 SD.
• Severe Acute Malnutrition (SAM): Defined as WFH < -3 SD.

D. Mid-Upper Arm Circumference (MUAC)

• Principle: Between 1 to 5 years, the arm circumference remains fairly constant. It measures muscle mass and subcutaneous fat.
• Utility: It is the best tool for community screening and predicting mortality risk.
• Cut-offs (6-59 months) using Tri-color Tape:
  • Red (< 11.5 cm): Severe Acute Malnutrition (SAM).
  • Yellow (11.5 to 12.4 cm): Moderate Acute Malnutrition (MAM).
  • Green ($\ge$ 12.5 cm): Normal.

E. Body Mass Index (BMI)

• Formula: Weight (kg) / Height ($m^2$).
• Application:
  • Used from birth to 20 years but is the primary parameter for adolescents (10-19 years).
  • Thinness: BMI for age < -2 SD.
  • Severe Thinness: BMI for age < -3 SD.
  • Underweight (Adolescents): BMI < 5th percentile (CDC charts) or < -2 SD (WHO).

3. Clinical Assessment

Clinical signs indicate severe or specific nutrient deficiencies.

A. Visible Severe Wasting

• Diagnosed by removing clothes and looking for loss of muscle and fat in the shoulders, arms, ribs, thighs, and buttocks.
• Baggy Pants Appearance: Loose skin folds on the buttocks due to extreme wasting of gluteal fat, characteristic of Marasmus.

B. Edema (Nutritional)

• Bilateral pitting edema is a cardinal sign of Kwashiorkor (Edematous Malnutrition).
• Test: Press thumbs gently on the dorsal aspect of both feet for 10 seconds. If a pit remains, edema is present.
• Any child with bipedal edema is classified as having Severe Acute Malnutrition (SAM) regardless of anthropometry.

C. Specific Deficiency Signs (Vitamin/Mineral)

• Vitamin A: Bitot’s spots, corneal xerosis, keratomalacia, night blindness.
• Iron: Pallor (palmar, conjunctival).
• Vitamin D (Rickets): Frontal bossing, wide open fontanelle, rachitic rosary, epiphyseal enlargement.
• Skin Changes: "Flaky paint" dermatosis, depigmentation, and "Crazy pavement" dermatosis are seen in Kwashiorkor.
• Hair Changes: Hypochromotrichia (discoloration), sparseness, easy pluckability, and "Flag sign" (bands of light and dark hair).

4. Classification Systems for Malnutrition

Various systems are used to grade the severity of undernutrition.

A. WHO Classification (Current Standard)

This is based on Z-scores (Standard Deviation Scores) derived from the WHO Multicentre Growth Reference Study (MGRS).

[Source: 147]

B. IAP Classification (1972)

Widely used in India historically, based on Weight-for-Age (Harvard standards).

Note: If edema is present, letter 'K' is added (e.g., Grade III K).

C. Wellcome Trust Classification

Based on Weight-for-Age and Edema.

D. Gomez Classification

The earliest classification based on Weight-for-Age.

• First Degree: 75–90% of expected weight.
• Second Degree: 60–75%.
• Third Degree: < 60% (Includes all cases with edema).

E. Waterlow’s Classification

Distinguishes between chronic and acute malnutrition.

• Stunting: Based on Height-for-Age (indicates past malnutrition).
• Wasting: Based on Weight-for-Height (indicates recent malnutrition).

5. Assessment of Adolescents (10-19 Years)

Adolescent growth is linked to puberty (SMR), making age-based standards difficult to apply solely.

• BMI-for-Age: The preferred parameter.
  • Thinness: < 5th Percentile (CDC) or < -2 SD (WHO).
  • Severe Thinness: < -3 SD.
• Sexual Maturity Rating (SMR): Tanner staging is essential to correlate growth with pubertal development, as malnutrition can delay puberty.

6. Definition of Severe Acute Malnutrition (SAM)

According to WHO and MOHFW India, a child (6-59 months) is defined as having SAM if they meet any one of the following criteria:

1. Weight-for-Height/Length: < -3 SD.
2. MUAC: < 11.5 cm.
3. Edema: Presence of bilateral pitting edema.

For infants < 6 months, SAM is defined by:

1. Weight-for-Length < -3 SD.
2. Visible severe wasting.
3. Bipedal edema.

7. Other Parameters

• Age-Independent Indices: Used when exact age is unknown.
  • Rao and Singh Index: Weight/Height${}^2$.
  • Kanawati Index: MUAC / Head Circumference ratio (< 0.25 indicates severe malnutrition).
• Biochemical: Low serum albumin, transferrin, and pre-albumin are indicators, but anthropometry is preferred for diagnosis.
• Developmental Assessment: Malnutrition affects brain growth; assessment of developmental milestones (gross motor, fine motor) is integral, using tools like the Trivandrum Developmental Screening Chart (TDSC).