Patient information. Please use browser translation settings. Also see vitamin D photoboard.

Background

Vitamin D is essential for bone and muscle health. Vitamin D refers to both D3 (cholecalciferol) and D2 (ergocalciferol). D3 is produced in the skin through the action of UVB in sunlight (see schema of physiology).¹ D3 is the most common form in food and the form available in supplements.  

Sunlight is the most important source of vitamin D, and is estimated to provide 90% of vitamin D.²

• The amount of UVB available varies with latitude, season, time of day, shade, and skin exposure (e.g. clothing).³ Window glass blocks UVB. There may not be enough UVB during winter in the southern states to maintain adequate vitamin D levels.⁴
• Adults with dark skin require around 5 times the amount of UVB compared to people with light skin to produce similar vitamin D levels^5,6 There still are no data on skin synthesis of vitamin D in children. Sunscreens do not result in low vitamin D with normal use in adults.⁷

Diet is a poor source of vitamin D, most Australians only get around 10% of their vitamin D from dietary sources.⁸

• Vitamin D is found naturally in few foods (D3 in some fatty fish, liver, eggs, some D2 in mushrooms).⁹ Some milk products are fortified with Vitamin D.
• Breastmilk contains almost no vitamin D (25 IU/L). Infant formula is fortified with D3 (360-520 IU/L and higher in pre-term formula).¹⁰

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/lactation.^4,10,11 

• RCH uses a chemiluminescence assay with ~10% variation. Around 1 mL blood (200 mcL serum) is required for analysis. When ordering tests ensure risk factors for vitamin D are clearly documented so Medicare Benefit Schedule (MBS) funding (item 66883) applies.
• To convert nmol/L to ng/mL divide by 2.5.

In the absence of sun exposure, recommended intakes are:⁹

• 12 months - adequate intake (AI) 400 IU daily.
• 1-18 years - estimated average requirement (EAR) 400 IU daily and recommended dietary allowance (RDA) 600 IU daily.

Risk factors for low vitamin D

Risk factors can be grouped as:¹⁰

• Lack of skin exposure to sun (time inside, chronic illness, complex disability, covering clothing (e.g. hijab, other religious/cultural styles), southerly latitude).
• Dark skin (Fitzpatrick types V and VI).
• Medical conditions/medications affecting vitamin D metabolism (obesity, liver failure, renal failure, malabsorption, TB medications, anticonvulsants).
• In infants: exclusive breastfeeding and any of the above risk factors, maternal vitamin D deficiency (cord levels ~65% maternal levels),¹² maternal covering clothing/hijab, or prematurity.

Prevalence

Refugee-background communities may have multiple risk factors for low vitamin D, e.g., dark skin, covering clothing and limited time outside. Low vitamin D continues to be common in clinical practice, especially for cohorts with dark skin or girls/women who wear hijab, and especially during winter.

• Studies from our service have found low vitamin D in 60-65% of new arrival Syrian and Iraqi,¹³ asylum seeker¹⁴ and Afghan cohorts¹⁵ and 33% Karen groups.¹⁶ A study of Ezidi refugee arrivals in NSW found low vitamin D in 83%.¹⁷
• Older studies found low vitamin D in 61–100% of refugee background African Australians in Melbourne, Adelaide and Sydney.^18-23
• Australian Health Survey data (2011-2013) found 36% of African Australians have low vitamin D.²⁴
• Australian case series of rickets from 2001 and 2006 found almost all children had cultural risk factors (dark skin, maternal covering clothing).^25,26
  

Assessment

• Time outside, covering clothing
• Dietary history - dairy intake, breastfeeding/formula in infants
• Previous vitamin D levels, previous/current treatment - see photoboard
  
• Non-specific bony and/or muscular pain; fatigue with exercise
• Poor growth, irritability, delayed motor milestones (young children)
  
• Symptoms of low calcium (muscle cramps, tetany, stridor). Hypocalcaemic seizures are rare beyond 6-12 months of age. 
• Family understanding of vitamin D and accessing supplements
  
• Growth parameters, exclusion of other musculoskeletal pathology
• Fitzpatrick skin type
  
• Delayed dentition (no teeth by 9 months, no molars by 14 months), enamel hypoplasia
  
• Rickets – deformity in growing bones due to failure of osteoid mineralisation. Peak incidence infancy, although deformity reflects age/growth (and can be in any direction). Consider other causes if asymmetrical. Look for long bone deformity, splaying (wrists, ankles), frontal bossing, delayed fontanel closure (normally closed by 2 years), rosary (widening of ribs at costochondral junction).         
  

Screening

• Screen children/adolescents with one or more risk factors for low vitamin D¹⁰
  • Measure vitamin D, Ca, PO4 and ALP. 
  • Also check PTH in those with low calcium intake, symptoms/signs or multiple risk factors.
    
    
• Infants with one or more risk factors for low vitamin D
  • In breastfed infants with at least one other risk factor it is usually practical to start supplements without screening - see below.
  • Consider checking levels (or adding daily supplements) in babies with risk factors for low vitamin D with mixed feeds or who have appropriately reduced their formula intake after starting solids. 
    
    
• Infants or children with rickets require additional baseline tests (and seek specialist advice)  
  • Measure vitamin D (25(OH)D and 1,25(OH)₂D), Ca, PO₄, Mg, ALP, PTH, UEC, urine Ca/PO₄/Creatinine, and X-rays (wrist, legs if deformity present), consider clinical photography.
    

Notes on screening

• Risk factor based screening remains consistent with current international evidence²⁷ and UK guidelines.²⁸
• When ordering tests, ensure risk factors for vitamin D are clearly documented so MBS funding (item 66883) applies.
• In recent arrivals with ongoing risk factors for low vitamin D: if the initial vitamin D level is normal, repeat at the end of the first winter in Australia.
• Levels at the start and end of winter can be useful to make a clinical judgment on dosing.
• Clinical photography is useful to monitor bony deformity. Nutritional rickets usually corrects after treatment of low vitamin D provided the child has adequate calcium and phosphate intake.

Management

Initial

• Admission symptomatic rickets or hypocalcaemia (including tetany, stridor, seizures) – these children may require intravenous calcium infusion and cardiac monitoring alongside management of low vitamin D (and exclusion of other causes) – do not give high dose Vitamin D in the outpatient setting to this group.
• Urgent specialist discussion/assessment - children with clinical rickets or abnormal serum calcium. Also seek specialist advice for vitamin D deficiency not responding to high dose supplements. 
  
  
• Children with low vitamin D should be treated to restore their levels to the normal range with either daily dosing or high dose therapy.
  • See dosing tables below.¹⁰ There is limited evidence to support high dose therapy in children age <3 months. See photoboard.
  • RCH uses 100,000 IU/ml D3 in olive oil. This solution is light and temperature sensitive and degrades to inactive vitamin D. The shelf life is 3 months if not kept in the fridge (with reduced potency at this time). It should be 90% potent at 3 months if stored <4°C.
  • Follow-up bloods at 3 months (earlier if rickets or infants <12 months) - 25(OH)D, Ca, PO4, ALP and also PTH if elevated initially.
    

• Children with nutritional rickets should be managed under specialist guidance. The minimum recommended dose of vitamin D is 2000 units daily for minimum of 3 months, together with oral calcium 500 mg daily (either via diet or supplements). Phosphate supplements may also be needed

• Breastfed infants can usually start supplements without screening. In babies with risk factors for low vitamin D with mixed feeds or who have appropriately reduced their formula intake after starting solids, also consider starting supplements without screening. See photoboard.
  • Infants on formula should receive adequate vitamin D from this source. There is no evidence for vitamin D supplementation in low risk formula fed infants. 
    
    
• Ensure adequate calcium intake and consider calcium supplements if dietary intake is poor (<2 serves dairy daily). See Australian NRV and intake table.
  • Cheese, yoghurt and fortified plant milks are alternatives for children who dislike cow milk. Lactose free milk is helpful if avoidance is due to lactose intolerance.
  • 1 cup cow milk contains ~300 mg calcium. One Caltrate^TM tablet contains 600 mg calcium. 
    
    
• Treatment should be paired with health education and advice about sun protection/sun exposure, encouraging outside play/activity. Children/young people with dark skin can tolerate intermittent sun exposure without sunscreen, although hats/sunglasses are still recommended. See Sunsmart handouts. Australian adult sun balance guidelines now address diversity noting that people with deeply pigmented skin are at low risk of skin cancer, but high risk of vitamin D deficiency and routine sun protection is not recommended.⁴
  

Self-management long-term

• Breastfed infants at risk of low vitamin D should be given 400 IU daily for at least the first 12 months.¹⁰
  • Infants on full formula feeds should receive adequate vitamin D from this source. 
  • Consider adding 400 IU daily in infants with risk factors for low vitamin D with mixed feeds or who have appropriately reduced their formula intake after starting solids. See photoboard.
    
    
• Children/young people with ongoing risk factors for low vitamin D need to understand this is a long-term issue – they require ongoing monitoring and a plan to maintain vitamin D and calcium through behavioural change and self-management where possible, and supplementation if required.
  
  
• Provide education and a plan for self-management e.g. 400-600 IU daily or 3000-4000 IU once weekly over the cooler months (May–August). This provides the EAR/RDA and should avoid blood testing and the need for high dose therapy. See dosing tables and photoboard.

Dosing table: Management of low vitamin D¹⁰

Calcium

Sun exposure¹⁰

References

• References