Growth Disorders

Growth Assessment Basics - Measuring Up!

• Normal Growth Phases:
  • Infancy: Rapid, decelerating growth.
  • Childhood: Slow, steady (approx. 5-7 cm/yr).
  • Puberty: Adolescent growth spurt.
• Growth Velocity: Rate of growth; key for early detection of deviations.
• Growth Charts:
  • WHO (0-5 yrs), IAP (>5-18 yrs) charts used in India.
  • Plot height, weight, head circumference.
  • Interpretation: Z-scores (SD from mean), percentiles.
• Bone Age (BA):
  • Assesses skeletal maturity & predicts adult height potential.
  • Methods: Greulich-Pyle (hand & wrist X-ray atlas), Tanner-Whitehouse (TW3).
  • ⭐ > Bone age is a better indicator of skeletal maturity and growth potential than chronological age.
• Mid-Parental Height (MPH):
  • Estimates genetic height potential.
  • Boys: $((\text{Father's Ht (cm)} + \text{Mother's Ht (cm)}) / 2) + \textbf{6.5} \text{ cm}$
  • Girls: $((\text{Father's Ht (cm)} + \text{Mother's Ht (cm)}) / 2) - \textbf{6.5} \text{ cm}$
  • Target height range: MPH $\pm \textbf{8.5}$ cm.

Short Stature - Little Big Issues

• Definition: Height < -2 SD or < 3rd percentile for age & sex.
• Classification:

  • Normal Variants: Familial Short Stature (FSS), Constitutional Delay of Growth & Puberty (CDGP).

    Feature	FSS	CDGP
    Bone Age (BA)	Matches Chronological Age (CA)	Delayed (BA ≈ Height Age < CA)
    Puberty	Normal timing	Delayed
    Adult Height	Matches mid-parental height (short)	Normal, within genetic potential
    Family History	Short stature	Delayed puberty/growth spurt

  • Pathological:

    • Proportionate vs. Disproportionate assessment is key.
    • Key Causes:
      • Endocrine: Growth Hormone Deficiency (GHD), Hypothyroidism.
      • Skeletal Dysplasias (Disproportionate): Achondroplasia.
      • Syndromic: Turner Syndrome, Noonan Syndrome.
      • Systemic Illness: Malnutrition, Chronic Kidney Disease (CKD).
      • Intrauterine Growth Retardation (IUGR) / Small for Gestational Age (SGA).

⭐ In Constitutional Delay of Growth & Puberty (CDGP), bone age is delayed and matches height age, and adult height is normal an_chieved eventually within genetic potential_

GH Axis & Disorders - The Height Controller

• GH-IGF-1 Axis Physiology: Hypothalamus (GHRH) → Anterior Pituitary (GH) → Liver & Tissues (IGF-1) → Growth.
  • 
• Growth Hormone Deficiency (GHD):
  • Causes: Congenital (e.g., genetic, pituitary hypoplasia) or acquired (e.g., CNS tumor, trauma, irradiation).
  • Clinical Features: Neonatal hypoglycemia, micropenis, prolonged jaundice, decreased growth velocity, cherubic facies.
  • Diagnosis:
    • Screening: ↓ IGF-1, ↓ IGFBP-3 levels (age-specific).
    • Confirmatory: GH stimulation tests (📌 Insulin, Arginine, Clonidine, L-DOPA). Peak GH response < 10 ng/mL is diagnostic.
  • Treatment: Recombinant human GH (rhGH).
• Laron Syndrome (GH Insensitivity):
  • Autosomal recessive; GH receptor defect.
  • Features: Similar to GHD, but with ↑ GH levels and ↓ IGF-1 levels.

⭐ IGF-1 levels are useful for screening GHD, but definitive diagnosis requires GH stimulation tests where peak GH < 10 ng/mL is a key criterion for GHD diagnosis in children after appropriate priming if necessary (e.g. with sex steroids in peripubertal children).

Syndromic & Other Deviations - Unique Growth Paths

• Turner Syndrome (45,X0): Short stature, ovarian dysgenesis, webbed neck, coarctation of aorta. 📌 CLOWNS: Cardiac, Lymphoedema, Ovarian dysgenesis, Webbed neck, Nipple (wide), Short stature.
• Noonan Syndrome (PTPN11): Short stature, distinct facies (e.g., hypertelorism, low-set ears), pulmonic stenosis.
• Achondroplasia (FGFR3): Rhizomelia (proximal limb shortening), trident hand.

  ⭐ Achondroplasia: Most common skeletal dysplasia. Autosomal dominant; most cases new FGFR3 mutations.

• Tall Stature (>+2SD / >97th percentile):
  • Causes: Familial, Marfan Syndrome (FBN1), Sotos Syndrome (NSD1), Klinefelter (47,XXY), precocious puberty, hyperthyroidism.

High‑Yield Points - ⚡ Biggest Takeaways

• Familial Short Stature (FSS): Bone age = Chronological age; normal growth velocity.
• Constitutional Delay (CDGP): Bone age < Chronological age; delayed puberty; normal adult height.
• GH Deficiency: ↓ Growth velocity, delayed bone age; GH stimulation tests for diagnosis.
• Turner Syndrome (XO): Female short stature, webbed neck; karyotyping confirms.
• Achondroplasia: Commonest skeletal dysplasia; disproportionate short stature; FGFR3 mutation.
• Congenital Hypothyroidism: Growth failure, delayed bone age; screen with TSH, free T4.
• SGA without catch-up: Risk of persistent short stature.