Notes

1. Definitions & Concepts

• Growth
  Growth refers to the measurable, quantitative increase in the physical dimensions of the body or its parts over time. In pediatrics, we track linear (height/length), ponderal (weight), and head circumference growth. These measurements reflect underlying processes such as cell multiplication, extracellular matrix expansion, and tissue maturation.

• Development
  Development describes qualitative changes: the acquisition of skills, new behaviors, and maturation of organ systems. It follows relatively predictable milestones (motor, language, social), which signal neural and muscular maturation.

• Maturation
  Maturation is the progression toward an adult state of physical, biochemical, and functional competence. It encompasses puberty, bone ossification, and the establishment of regulatory axes (e.g., hypothalamic–pituitary–gonadal). Genetics set the potential, while environment and nutrition modulate its timing and pace.

2. Phases of the Growth Curve

The human growth trajectory roughly follows an S-shaped (sigmoid) pattern:

1. Infancy (0–2 years)

   • Velocity: Extremely rapid—average weight gain ~20–25 g/day; length increases ~25 cm in the first year.

   • Landmarks: Birth weight doubles by 5–6 months, triples by 12 months; length increases by about 50% at 12 months.

   • Regulators: Nutrition (breastmilk/formula), IGF-1, insulin, thyroid hormones.

2. Childhood (2 years to puberty)

   • Velocity: Steady linear growth of ~5–7 cm/year and weight gain of ~2–3 kg/year.

   • Regulators: Growth hormone (pulsatile), thyroid hormone, balanced nutrition.

   • Clinical Note: Deviations here often indicate chronic illness, nutritional deficits, or endocrine disorders.

3. Puberty/Adolescence

   • Onset: Girls ~10–14 years; boys ~12–16 years.

   • Growth Spurt: Peak velocity ~8–11 cm/year in girls and ~9–12 cm/year in boys.

   • Hormonal Drivers: Rising sex steroids (estrogen/testosterone) synergize with growth hormone and IGF-1.

   • Bone Maturation: Epiphyseal growth plates begin to fuse under sex steroids’ influence.

4. Completion (Post-adolescence)

   • Girls: Growth ceases ~18 years;

   • Boys: ~20 years.

   • Mechanism: Epiphyseal closure in long bones; adult height reached.

3. Anthropometric Measurements

Accurate measurement is essential for tracking growth:

• Weight

  • Use calibrated infant scales (±10 g) for <2 years; standing scales (±100 g) thereafter.

  • Plot against age-and-sex–specific weight-for-age charts.

• Length / Height

  • Recumbent length for infants (tape or infantometer), standing height for older children using a stadiometer.

  • Plot on length/height-for-age charts to detect stunting.

• Head Circumference

  • Measure up to 36 months over the maximum occipito-frontal circumference.

  • Reflects brain growth; deviations may indicate microcephaly or hydrocephalus.

• Mid-Upper Arm Circumference (MUAC)

  • Simple field measure for acute malnutrition in 6–59 months:

    • ≥ 12.5 cm normal;

    • 11.5–12.5 cm moderate;

    • < 11.5 cm severe acute malnutrition.

• Skinfold Thickness

  • Triceps and subscapular measurements estimate subcutaneous fat but require skill and are less routinely used.

4. Growth Charts & Percentiles

• Standards vs. References

  • WHO 0–5 years (standards) describe how children should grow under optimal conditions.

  • CDC 2–20 years (references) describe how US children grew historically.

• Percentile Interpretation

  • 50th percentile = median (typical).

  • < 3rd percentile or > 97th percentile warrants evaluation.

• Crossing Percentiles

  • A child’s plotted growth curve should remain within roughly the same percentile band.

  • A drop or rise across two major percentile lines suggests an underlying problem (e.g., malnutrition or endocrine disorder).

5. Growth Velocity

• Definition & Importance

  • Velocity = change in measurement per unit time (e.g., cm/year).

  • More sensitive than static percentile for detecting early growth disorders—a slowing velocity can precede percentile crossing.

• Normal Values

  • First year: ~25 cm;

  • Years 2–puberty: ~5–6 cm/year;

  • Pubertal peak: as above.

• Clinical Use

  • Chart height increments every 6–12 months, weight every 1–3 months; compare to expected norms.

6. Assessment of Growth Disorders

• Failure to Thrive (FTT)

  • Weight-for-age < 5th percentile or downward crossing of two percentile lines on weight curve.

• Stunting

  • Height-for-age < –2 SD (below 3rd percentile); indicates chronic undernutrition or long-term illness.

• Wasting

  • Weight-for-height < –2 SD; acute malnutrition, dehydration.

• Underweight

  • Weight-for-age < –2 SD; may reflect acute or chronic issues.

• Overweight & Obesity

  • BMI-for-age ≥ 85th percentile (overweight), ≥ 95th percentile (obesity); linked to insulin resistance, fatty liver.

7. Causes of Abnormal Growth

• Genetic & Syndromic

  • Turner syndrome, Noonan syndrome, achondroplasia: characteristic phenotypes, short stature.

• Endocrine Disorders

  • GH deficiency (idiopathic or pituitary), hypothyroidism; present with slowed growth velocity, delayed bone age.

• Nutritional

  • Caloric/protein deficiency, micronutrient shortages (iron, zinc), malabsorption (celiac disease).

• Chronic Illness

  • Congenital heart disease, chronic kidney disease, cystic fibrosis—inflammatory cytokines and energy imbalance impair growth.

• Psychosocial

  • Neglect or emotional deprivation can cause “psychosocial dwarfism,” reversible with environmental change.

• Constitutional Growth Delay

  • Family history of late puberty; bone age delayed by 1–2 years, final height normal but puberty late.

8. Investigations

• Bone Age X-Ray

  • Left-hand–wrist radiograph compared to Atlas (Greulich & Pyle); assesses skeletal maturity relative to chronological age.

• Laboratory Evaluation

  • CBC, ESR/CRP (inflammation); renal/hepatic panels; thyroid function tests; celiac serology.

  • IGF-1 and IGFBP-3 levels reflect GH axis but are age-dependent.

• Endocrine Testing

  • GH stimulation tests (e.g., insulin tolerance test); cortisol levels if adrenal deficiency suspected.

• Genetic & Imaging

  • Karyotype for suspected Turner or other syndromes; MRI pituitary if GH deficiency confirmed.

9. Management Principles

1. Nutritional Rehabilitation

   • Ensure caloric intake meets ~100 kcal/kg/day (infants), tapering to age-appropriate needs; high-protein diet for catch-up.

2. Disease-Specific Therapy

   • Thyroxine for hypothyroidism; gluten-free diet for celiac; optimize cardiac/renal function in chronic disease.

3. Hormone Replacement

   • Recombinant GH for proven GH deficiency: typically 0.025–0.035 mg/kg/day subcutaneously.

4. Psychosocial Intervention

   • In psychosocial dwarfism, placement in supportive foster care or family counseling often restores normal growth within weeks.

5. Follow-Up

   • Monitor weight monthly, height quarterly; adjust interventions based on growth response.

10. High-Yield “Exam Pearls”

• Birth weight doubles by 5–6 months, triples by 12 months; length +50% at 1 year.

• MUAC < 11.5 cm in 6–59 months = severe acute malnutrition.

• Constitutional delay: bone age 1–2 years behind, delayed puberty but normal final height.

• Psychosocial dwarfism shows low GH levels that normalize once removed from stress.

• GH stimulation test is gold-standard—baseline IGF-1 alone is insufficient.

Table- 

Phases of Growth Curve