Harvey's Garden

Osteomalacia and rickets

2 min read

  • Definition & Pathophysiology
    • Defective mineralization of osteoid (bone matrix).
    • Rickets: Occurs in children (open growth plates); defective mineralization of cartilaginous growth plates.
    • Osteomalacia: Occurs in adults (closed growth plates); defective mineralization of osteoid.
    • Contrast with Osteoporosis: Osteoporosis is loss of mineralized bone mass (normal mineralization, ↓ quantity); Osteomalacia is poor quality/soft bone (↓ mineralization).
  • Etiology
    • Vitamin D Deficiency (Most common)
      • ↓ Sun exposure, malnutrition (breastfed infants without supplementation).
      • Malabsorption (Celiac disease, Crohn’s, Cystic Fibrosis).
    • Chronic Kidney Disease: Impaired 1α-hydroxylation of Vit D (calcidiol → calcitriol).
    • Hypophosphatemia: Renal tubular acidosis (Type 2), Fanconi syndrome.
  • Clinical Features
    • Rickets (Children)
      • Craniotabes: Softening of skull bones (ping-pong ball sensation).
      • Frontal Bossing: Prominent forehead.
      • Rachitic Rosary: Beading of costochondral junctions (enlarged due to osteoid accumulation).
      • Genu Varum/Valgum: Bowing of legs (weight-bearing leads to bending of soft bones).
      • Delayed fontanelle closure, delayed dentition.
    • Osteomalacia (Adults)
      • Diffuse bone pain and tenderness.
      • Proximal muscle weakness.
      • Waddling gait.
      • Pathologic fractures (vertebral, hip).
  • Laboratory Findings
    • Calcium: ↓ or Normal (maintained by secondary PTH response)
    • Phosphate: ↓ (PTH causes phosphate dumping in kidney)
    • PTH: ↑ (Secondary Hyperparathyroidism)
    • Alkaline Phosphatase (ALP): ↑↑ (Reflects increased osteoblast activity trying to mineralize bone)
    • 25-OH Vitamin D: ↓
  • Diagnostics / Imaging
    • Rickets:
      • X-ray: Widening and fraying of metaphyseal ends (“cupping”).
      • Epiphyseal plate widening.
    • Osteomalacia:
      • X-ray: Looser zones (Pseudofractures) – radiolucent lines perpendicular to cortex, often at femoral neck or pubic rami.
    • Bone Biopsy: Massive accumulation of unmineralized osteoid (thickened osteoid seams).
  • Treatment
    • Vitamin D supplementation (Ergocalciferol or Cholecalciferol).
    • Adequate dietary Calcium and Phosphate.
    • Check for underlying malabsorption if refractory.

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