Rickets: Vitamin D Deficiency, Symptoms, Complications & Treatment

Rickets is defective mineralization of growing bone due to vitamin D, calcium, or phosphate deficiency. Occurs in children; adult equivalent is osteomalacia.

Pathophysiology

• ↓ 1,25(OH)₂D → ↓ intestinal Ca²⁺/PO₄ absorption → ↓ serum Ca²⁺/PO₄ → ↑ PTH → renal phosphate wasting → inadequate mineralization of growth plates & osteoid.

Clinical Features

• Skeletal: Widening wrists/ankles, costochondral beading (rachitic rosary), Harrison's groove, bowlegs (genu varum) or knock-knees, craniotabes, delayed fontanelle closure.
• Muscular: Hypotonia, delayed motor milestones, proximal weakness.
• Dental: Enamel hypoplasia, delayed eruption, caries.
• Systemic: Irritability, poor growth, tetany (if severe hypocalcemia).

Severe Complications

• Hypocalcemic seizures, tetany, laryngospasm.
• Cardiomyopathy, heart failure (rare).
• Respiratory compromise from chest deformity.
• Permanent skeletal deformities if untreated during growth.

Diagnosis

• Labs: ↓ 25(OH)D (<12 ng/mL), ↓ Ca²⁺/PO₄, ↑ ALP, ↑ PTH.
• X-ray: Cupping, fraying, widening of metaphyses (wrist/knee).

Treatment

• Stoss Therapy (High-Dose): Vitamin D₃ 50,000–100,000 IU weekly ×4–8 wks (or single 300,000–600,000 IU IM/oral).
• Daily Maintenance: 400–1000 IU/day (AAP) after repletion.
• Calcium 500–1000 mg/day elemental.
• Monitor: ALP normalization (3–6 mo), radiograph healing (6–12 mo), 25(OH)D >20 ng/mL.
• Orthopedic referral for residual deformities after growth completion.

Prevention

• 400 IU/day vitamin D from birth (breastfed infants).
• Dietary calcium (dairy, fortified foods, leafy greens).
• Safe sun exposure (latitude/season/skin tone dependent).