Vitamin D dosage Serum vitamin D

Dosage of vitamin d3 for child

See also

Immigrant Health Guideline – Low Vitamin D
Sun Protection
Vitamin D supplements photoboard

Key points

  1. Vitamin D is essential for bone and muscle health. Low vitamin D and low calcium and/or phosphate can cause nutritional rickets
  2. Sunlight is the most important source of vitamin D at all ages
  3. Vitamin D deficiency is common in risk groups and should be self-managed wherever possible - through education, behaviour change and supplementation as required
  4. In Australia, nutritional rickets is generally only seen in infants and children with dark skin

Background

  • Sunlight [UVB] is the most important source of vitamin D [>90%] through skin synthesis of D3. This varies with
    • Skin colour: people with dark skin [ Fitzpatrick types V and VI] require greater UVB exposure compared to people with light skin
    • Skin exposure: covering clothing may result in low vitamin D levels
    • Season/UVB availability: during winter there may not be enough UVB to maintain adequate vitamin D levels in southerly latitudes. Sunscreens do not result in low vitamin D with normal use
  • Only small amounts of vitamin D are available from diet:
    • the main natural food source is fish
    • breastmilk, despite its other benefits, contains almost no vitamin D
    • infant formula is fortified with vitamin D
  • In the absence of sun exposure, recommended intakes of vitamin D are:
    • 0–12 months old: 400 units daily
    • 1–18 years old: 400–600 units daily
  • 25-OH-D is used to measure vitamin D status
  • The recommended 25-OH-D level is ≥50 nmol/L at all ages and during pregnancy

Definitions of vitamin D status

Severe deficiency

250 nmol/L with hypercalcaemia and suppression of parathyroid hormone [PTH]

Assessment

Red flag features in Red

Risk factors

  • Lack of skin exposure to sun [time inside, covering clothes]
  • Dark skin
  • Medical conditions affecting Vitamin D metabolism [obesity, liver/renal failure, severe malabsorption, medications]

Infants: exclusive breastfeeding AND any of: the above risk factors, maternal deficiency or prematurity

History

  • Time outdoors and covering clothing
  • Dietary history [calcium intake, breastfeeding/formula in infants]
  • Previous vitamin D levels and treatment
    • a wide range of formulations are available
    • check dosing [ photoboard] and adherence
  • Family understanding
  • Non-specific bony/muscular pain, fatigue with exercise
  • Poor growth, motor delay and irritability [infants]
  • Symptoms of low calcium: muscle cramps, tetany, stridor, seizures [rare beyond 6–12 months of age]

Examination

  • Growth parameters, exclusion of other musculoskeletal pathology
  • Fitzpatrick skin type
  • Delayed dentition [no teeth by 9 months, no molars by 14 months]
  • Rickets:
    • long bone deformity [eg genu varum/valgus - if weight bearing]
    • widening of wrists/ankles
    • delayed anterior fontanelle closure [normally closed by 2 years]
    • frontal bossing
    • rosary [widening of ribs at costochondral junction]
    • increased risk of fracture

Management

Flowchart - Investigation and treatment of low vitamin D