Paediatrics: Rickets

2021-03-03 12:00 AM

A disorder of the growing skeleton due to inadequate mineralization of bone as it is laid down at the epiphyseal growth plates.

Rickets

A disorder of the growing skeleton due to inadequate mineralization of bone as it is laid down at the epiphyseal growth plates. There is a characteristic widening of the ends of long bones and characteristic radiology. Osteomalacia occurs when there is inadequate mineralization of mature bone. Both rickets and osteomalacia may be present at the same time.

Causes

Malnutrition and calcium deficiency are common causes worldwide. Vitamin D deficiency is rare in developed countries, although inadequate exposure to sunlight and exclusive breastfeeding of 6–12mths during infancy are well-recognized causes.

Calcium deficiency 

Dietary; malabsorption.

Vitamin D

 Vitamin D deficiency: dietary; malabsorption; lack of sunlight; iatrogenic(drug-induced, e.g. phenytoin therapy).

  • Defect in vitamin D metabolism: vitamin D-dependent rickets type I(1A-hydroxylase deficiency); liver disease; renal disease.
  • Defect in vitamin D action: vitamin D-dependent rickets type II.

Phosphate deficiency

  • Renal tubular phosphate loss (isolated): hypophosphataemic rickets:
  • X-linked;
  • autosomal recessive;
  • autosomal dominant.
  • Acquired hypophosphataemic rickets:
  • Fanconi syndrome;
  • renal tubular acidosis;
  • nephrotoxic drugs.
  • Reduced phosphate intake.

Clinical features

  • Growth delay or arrest.
  • Bone pain and fracture.
  • Muscle weakness.
  • Skeletal deformities:
  • swelling of wrists;
  • swelling of costochondral junctions (‘rickety rosary’);
  • bowing of the long bones;
  • frontal cranial bossing;
  • craniotabes (softening of the skull).