History and examination

  • Dietary history from birth.
  • Exposure to sunlight (child and mother).
  • Use of drugs and multivitamins.
  • Motor development.
  • Measure and accurately plot height and weight.
  • Assess general nutritional status.
  • Look for classical signs of rickets.

Investigations

  • Left wrist X-ray in children <3 years old, knee X-ray in children >3 years old.
  • Serum urea, electrolytes, creatinine.
  • Bone profile (Ca, Mg, Phosphate, Alkaline Phosphatase).
  • Liver function tests.
  • Full blood count.
  • PTH.
  • 25 Hydroxy Vitamin D.

Diagnosis

The classical biochemical picture of vitamin D deficiency is:

  • Calcium – Normal or low.
  • Phosphate – Normal or low.
  • Alkaline phosphatase – Raised.
  • PTH – Normal or raised.
  • 25 Hydroxy cholecalciferol (25OHCC) – Low.

Vitamin D serum concentrations

  • Deficiency – Less than 30nmol/L.
  • Insufficiency – 30 to 50nmol/L.
  • Sufficiency – Above 50nmol/L.