Commonest

Nutritional Vitamin D deficiency +/- Ca deficiency.

Consider

  • malabsorption
  • phosphate deficiency
  • liver disease
  • renal disease
  • anticonvulsant therapy
  • hypophosphataemic rickets
  • hypo and pseudohypoparathyroidism
  • Vitamin D dependent rickets (types I & II)
  • renal tubular tisorders
  • tumour-induced.

(Vitamin D deficiency may be confused with skeletal dysplasia).