Vitamin D deficiency in children with thanks to Dr Jini Haldar, paediatric registrar at Whipps Cross University Hospital.

Introduction

Vitamin D is an essential nutrient needed for healthy bones, and to control the amount of calcium in our blood. There is recent evidence that it may prevent many other diseases.  There are many different recommendations for the prevention, detection and treatment of Vitamin D deficiency in the UK.  The one outlined below is what we tend to do at Whipps Cross Hospital.

 Prevention

The Department of Health and the Chief Medical Officers recommend a dose of 7-8.5 micrograms (approx. 300 units) for all children from six months to five years of age. This is the dose that the NHS ‘Healthy Start’ vitamin drops provide. The British Paediatric and Adolescent Bone Group’s recommendation is that exclusively breastfed infants receive Vitamin D supplements from soon after birth. Adverse effects of Vitamin D overdose are rare but care should be taken with multivitamin preparations as Vitamin A toxicity is a concern. Multivitamin preparations often contain a surprisingly low dose of Vitamin D.

Indications for measurement of vitamin D

 1. Symptoms and signs of rickets/osteomalacia

• Progressive bowing deformity of legs
• Waddling gait
• Abnormal knock knee deformity (intermalleolar distance > 5 cm)
• Swelling of wrists and costochondral junctions (rachitic rosary)
• Prolonged bone pain (>3 months duration)

2. Symptoms and signs of muscle weakness

• Cardiomyopathy in an infant
• Delayed walking
• Difficulty climbing stairs

3. Abnormal bone profile or x-rays

• Low plasma calcium or phosphate
• Raised alkaline phosphatase
• Osteopenia or changes of rickets on x-ray
• Pathological fractures

4. Disorders impacting on vitamin D metabolism

• Chronic renal failure
• Chronic liver disease
• Malabsorption syndromes, for example, cystic fibrosis, Crohn’s disease, coeliac disease
• Older anticonvulsants, for example, phenobarbitone, phenytoin, carbamazepine

5. Children with bone disease in whom correcting vitamin D deficiency prior to specific treatment would be indicated:

• Osteogenesis imperfecta
• Idiopathic juvenile osteoporosis
• Osteoporosis secondary to glucocorticoids, inflammatory disorders, immobility

Symptoms and signs in children of vitamin D deficiency

1. Infants: Seizures, tetany and cardiomyopathy

2. Children: Aches and pains: myopathy causing delayed walking; rickets with bowed legs, knock knees, poor growth and muscle weakness

3. Adolescents: Aches and pains, muscle weakness, bone changes of rickets or osteomalacia

Risk factors for reduced vitamin D levels include:

• Dark/pigmented skin colour e.g. black, Asian populations
• Routine use of sun protection factor 15 and above as this blocks 99% of vitamin D synthesis
• Reduced skin exposure e.g. for cultural reasons (clothing)
• Latitude (In the UK, there is no radiation of appropriate wavelength between October and March)
• Chronic ill health with prolonged hospital admissions e.g. oncology patients
• Children and adolescents with disabilities which limit the time they spend outside
• Institutionalised individuals
• Photosensitive skin conditions
• Reduced vitamin D intake
• Maternal vitamin D deficiency
• Infants that are exclusively breast fed
• Dietary habits – low intake of foods containing vitamin D
• Abnormal vitamin D metabolism, abnormal gut function, malabsorption or short bowel syndrome
• Chronic liver or renal disease

Management depends on the patient’s characteristics:

 A. No risk factors

No investigations, lifestyle advice* and consider prevention of risk factors

B. Risk Factors Only

1. Children under the age of 5 years: Lifestyle advice* and vitamin D supplementation.

Purchase OTC or via Healthy Start

Under 1 year: 200 units vitamin D once daily

1 – 4 years: 400 units vitamin D once daily

2. Children 5 years and over – offer lifestyle advice*

C. Risk Factors AND Symptoms, Signs

Lifestyle advice*

Investigations:

• Renal function, Calcium, Phosphate, Magnesium (infants), alkaline phosphatase,
• 25-OH Vitamin D levels, Urea and electrolytes, parathyroid hormone

Children can be managed in Primary Care as long as:

• No significant renal impairment
• Normal calcium (If <2.1 mmol/l in infants, refer as there is a risk of seizures)

If further assessment is required consider referral to specialist. **

Patient’s family is likely to have similar risk of Vitamin D deficiency – consider investigation ant treatment if necessary.

*Life style advice

1. Sunlight

Exposure of face, arms and legs for 5-10 mins (15-25 mins if dark pigmented skin) would provide good source of Vitamin D. In the UK April to September between 11am and 3pm will provide the best source of UVB. Application of sunscreen will reduce the Vitamin D synthesis by >95%. Advise to avoid sunscreen for the first 20-30 minutes of sunlight exposure. Persons wearing traditional black clothing can be advised to have sunlight exposure of face, arms and legs in the privacy of their garden.

2. Diet

Vitamin D can be obtained from dietary sources (salmon, mackerel, tuna, egg yolk), fortified foods (cow, soy or rice milk) and supplements. There are no plant sources that provide a significant amount of Vitamin D naturally.

  **Criteria for referral

• Criteria for management in primary care not met
• Deficiency established with absence of known risk factors
• Atypical biochemistry (persistent hypophosphatemia, elevated creatinine)
• Failure to reduce alkaline phosphatase levels within 3 months
• Family history (parent, siblings) with severe rickets
• Infants under one month with calcium <2.1mmmol/l at diagnosis as risk of seizure.  (Check vitamin D level of mothers in this group immediately and treat, particularly if breast feeding.)
• If compliance issues are anticipated or encountered during treatment.
• Satisfactory levels of vitamin D not achieved after initial treatment.

  Vitamin D levels, effects on health and management of deficiency

Course length is 8 – 12 weeks followed by maintenance therapy.

 Checking of levels again

As Vitamin D has a relatively long half-life levels will take approximately 6 months to reach a steady state after a loading dose or on maintenance therapy. Check serum calcium levels at 3 months and 6 months, and 25 – OHD repeat at 6 months. Review the need for maintenance treatment.  NB:  the Barts Health management protocol uses lower treatment doses for a minimum of 3 months and then there is no need for repeat blood tests in the majority of cases of children satisfying the criteria for management in primary care.

 Serum 25 OHD after 3 months treatment Action

It is essential to check the child has a sufficient dietary calcium intake and that a maintenance vitamin D dose follows the treatment dose and is continued long term.

Follow-up:

Some recommend a clinical review a month after treatment starts, asking to see all vitamin and drug bottles. A blood test can be repeated then, if it is not clear that sufficient vitamin has been taken.

Current advice for children who have had symptomatic Vitamin D deficiency is that they continue a maintenance prevention dose at least until they stop growing. Dosing regimens vary and clinical evidence is weak in this area. The RCPCH has called for research to be conducted.  The RCPCH advice on vitamin D is at http://www.rcpch.ac.uk/system/files/protected/page/vitdguidancedraftspreads%20FINAL%20for%20website.pdf

JINI HALDAR