Disorders of Growth

Growth Fundamentals - Charting the Heights

• Monitor: IAP charts (WHO <5y, IAP >5y).
• Height Velocity (HV):
  • Prepubertal: 5-6 cm/yr.
  • Pubertal: Girls 8-10 cm/yr, Boys 10-12 cm/yr.
• Mid-Parental Height (MPH):
  • Boys: $(H_{F} + H_{M} + 13)/2$ cm.
  • Girls: $(H_{F} + H_{M} - 13)/2$ cm.
  • Target range: MPH $\pm$ 8.5 cm.
• Bone Age (BA): X-ray L hand/wrist (Greulich-Pyle).

⭐ A fall-off from a previously established growth percentile (height or HV) is more significant than a single low measurement.

Short Stature - Little Sprout Issues

Height < -2 SD or < 3rd percentile for age & sex; or growth velocity < 25th percentile over 1 year.

Initial Assessment:

• History (birth, nutrition, family Hx, systemic illness)
• Exam: Anthropometry (height, weight, HC), U/L segment ratio, dysmorphism
• Bone Age (X-ray left hand & wrist)
• Mid-Parental Height (MPH) Target Range:
  • Boys: $(Father's Ht_{cm} + Mother's Ht_{cm} + 13) / 2 \pm 8.5 cm$
  • Girls: $(Father's Ht_{cm} + Mother's Ht_{cm} - 13) / 2 \pm 8.5 cm$

Key Investigations:

• CBC, ESR, Urinalysis, KFT, LFT, Celiac serology
• TSH, Free T4, IGF-1, IGFBP-3
• Karyotype (all girls with unexplained short stature)
• GH stimulation tests (if IGF-1 low/borderline & other causes excluded)

⭐ Turner Syndrome (45,XO) is a key cause of unexplained short stature in girls; always consider karyotyping. Early GH therapy improves final height.

📌 Mnemonic: SHORT

• Systemic illness / Skeletal dysplasia
• Hypothyroidism / Hormonal (GHD, Cushing)
• Others (Psychosocial, IUGR/SGA)
• Renal (CKD) / Rickets
• Turner's / T familial (FSS, CDGP - constitutional delay)

Tall Stature - Giant Growth Tales

• Definition: Height > 2 SD or > 97th percentile for age & sex.
• Evaluation: Family Hx, growth velocity, Bone Age (BA) assessment.
• Causes:
  • Familial (most common).
  • Endocrine: GH excess (Gigantism), Precocious Puberty (initial ↑ height), Hyperthyroidism.
  • Genetic: Marfan Syndrome, Klinefelter Syndrome, Sotos Syndrome, Beckwith-Wiedemann Syndrome.
• 📌 Gigantism: GH excess before epiphyseal fusion; Acromegaly after.

⭐ Sotos Syndrome: Macrocephaly, advanced BA, distinctive facies (prominent forehead, pointed chin), intellectual disability often present.

Key Syndromes - Growth's Unique IDs

• Short Stature Syndromes:
  • Turner S. (45,XO): Webbed neck, shield chest, ovarian dysgenesis, coarctation.
  • Noonan S. (PTPN11): Turner-like, pulmonary stenosis, pectus carinatum.
  • Prader-Willi S. (15q del): Neonatal hypotonia, hyperphagia, obesity, hypogonadism.
  • Russell-Silver S. (Chr7/11): IUGR, triangular face, asymmetry, normal HC.
• Tall Stature Syndromes:
  • Klinefelter S. (47,XXY): Eunuchoid, gynecomastia, small testes, infertility.
  • Marfan S. (FBN1): Arachnodactyly, ectopia lentis, aortic dilation.
  • Sotos S. (NSD1): Macrocephaly, advanced bone age, ID.
  • Beckwith-Wiedemann S. (11p15): Macrosomia, macroglossia, omphalocele, hemihypertrophy.

    ⭐ BWS requires regular screening for Wilms' tumor & hepatoblastoma (↑risk).

Diagnostic Path - Growth Clue Hunt

⭐ Growth velocity < 4 cm/yr (4 yrs-puberty) or < P25 is a red flag.

High‑Yield Points - ⚡ Biggest Takeaways

• Familial Short Stature (FSS): Normal bone age & growth velocity; matches parental height.
• Constitutional Delay (CDGP): Delayed bone age, normal growth velocity; family history of late bloomers.
• GH Deficiency: Delayed bone age, ↓ growth velocity, ↓ IGF-1; confirm with GH stimulation tests.
• Turner Syndrome (XO): Short stature in females, webbed neck, streak ovaries; karyotype is key.
• Achondroplasia: Commonest skeletal dysplasia; disproportionate short stature, rhizomelia.
• Hypothyroidism: Growth failure, delayed bone age, ↑ TSH, ↓ T4; treat with levothyroxine.