vitamin d deficiency in children: a call for a network approach colin michie no commercial interests...
TRANSCRIPT
Vitamin D Deficiency in Children:
a call for a network approach
Colin Michie
No commercial interestsNo conflicts of interest
Ealing Hospital ICO
Outline
• Why children?
• Perspectives
• What initiated my interest in vitamin D?• Patters of variation • Implications for presentation, diagnosis, treatment
(including a brief look at vitamin D toxicity)• Problems identified relating to vitamin D in west London• Gap analysis: precautions, monitoring: a networked
approach
Some biology and paediatrics
• Biological view of infant mortality
• Nutrition in pregnancy, infancy, breast-feeding• Adolescents and the next generation• Social evolution • Imprinting or late effects
The infant is the crucible of our species (we must strive to get infancy right!)
A series of hypocalcemic
seizures
• January 2007 three hypocalcemic seizures presented over a weekend in Ealing Hospital
• Case series: 18 cases (M 8, age 2.5-6 weeks)• Corrected calcium levels at presentation (1.19-1.46 mmol/l normal
2.15-1.55)• Vitamin D levels at presentation (2.3-15 nmol/l)• Alkaline phosphatase (350-2300 IU/l, normal up to 300)• Ethnicity (15 Asian or Afro-Caribbean, 7 Somalian)
The biology of vitamin D deficiency is variable
4 years later
• 13 well and asymptomatic, normal growth patterns (others lost to follow-up)
• 4/13 achieved 1,25 OHD > 80 nmol/l, 3/13 never > 50 nmol/l• 4/13 showed gross motor delays• 2/13 have damage to tooth enamel• Follow-up continues
The outcome of severe deficiency varies; moderate to mild deficiency is common
Serum Vitamin DOctober 2009 to December 2009
65
1231
1105
790
312 292240 226 205
159127 109 85
59 8149
22 37
0
200
400
600
800
1000
1200
1400
10 20 30 40 45 50 55 60 65 70 75 80 85 90 100 110 120 >120
Serum Vitamin D nmol/L
Fre
qu
ency
Homo sapiens
• We are the same species!
Variation…
Variation
• ‘Hapmap 3’: http://hapmap.ncbi.nlm.nih.gov/publications.html.en
• Binding to sites on genome• Binding to sites with known disease associations• Clinical associations
Just how wide is the variation in our species in the responses/biology of vitamin D?
The complex system
Variations
• Rates at which system functions • Metabolic activity of components (vitamers)• Binding proteins for individual metabolites• Role of other metabolites e.g. calcium,
phosphate, magnesium, vitamin A
A helpful cloud?
Return to biology
• The complex system has at least two rate limiting points:
• Skin (homeostatic system)• Renal hydroxylation (Type 1)• ? Intranuclear (Type 2)
What is the outcome of abnormalities at these points? Studies of rare disorders have value
The complex system
Some unpopular points
• Normal curves – what about the top 5%?• Crucial to define in order to proceed with clear risk
definitions• The vitamin OTC market has proved recession resistant:
how can we find out about self-medication?• Prescriptions for vitamin D are soaring
A problem at the zoo…
Vitamin D Toxicity
• What biological system should one test?• What are the variations within populations?• What level of vitamin D is dangerous, what level is
‘toxic’?• Hypercalcemia and hypercalcuria, with fatigue, muscle
pain or weakness, polyuria and polydipsia, high blood pressure [blood tests… 24 hour urine tests…!]
• BPSU study planned
Returning to Ealing…
• In 2011/2012: known 4 cases of hypercalcemia, one symptomatic, related to vitamin D overdose. All caused by over-supplementation by parents. • Corrected serum calcium: 2.7-3.0, urinary calcium > 350 mg/day
in all cases
• Others have observed unexpected levels of hypercalcemia
• No good epidemiology relating to this problem: what is the system whereby overdose is managed and preferably avoided?
Problems identified
• Lack of knowledge relating to vitamin D in antenatal clinics, both among mothers and staff. No concept of requirement or risk Identified in adolescents in ward school
• Lack of compliance with national recommendation for vitamin supplements and antenatal care; Healthy Start vitamins not available, licence debates
• Lack of appreciation of the importance of obesity• Maps…
Geography of hypocalcemic
seizure
Geography: blood tests for
vitamin D
Geography: Top 10 prescribing
practices for vitamin D supplements
Mapping observations
• There is variation in clinical symptoms and care provision at the level of the street
• The distribution of cases corresponds with socioeconomic factors
• There is no more/very little new funding to change this• (High levels of vitamin D were in W5 and W13)
Gaps
• Deficiency in this nutrient, related to geography and lifestyle, particularly for lower socioeconomic groups
• Distances between scientific knowledge and clinicians are growing
• Sources of messages or information relating to vitamin D are diversifying and multiplying
• UK studies show varied understanding, poor compliance with existing guidelines, incomplete guidelines and problems with reasonably priced, licensed medications
• There will be no more funding
Systems analysis: educate the public and professionals, develop a network, manage that network
Stratgies for the future
• Introduce yourself to your neighbours: network• Clinical networks (www.rcpch.ac.uk/networks)
• Create, participate, identify goals, publish• Guidelines needed: concordance and publication
• Maps (www.rightcare.nhs.uk)• Standards• Peer review
Conclusions
• Vitamin D deficiency is a public health problem, treatment of which will require a robust approach including careful monitoring
• Accurate and informed education of the public and professionals is required
• Meetings of this nature are critical in establishing a network to promote responsible management
RCPCH Nutrition [email protected]@nhs.net
Acknowledgements and Thanks
• The organisers of this meeting
• Patients and colleagues who have helped collect details and perform audits (school teachers and junior mayor)
• Patients and colleagues who have, and I hope will continue to point out my significant areas of ignorance