Copyright © 2008 Royal Australian College of General Practitioners Copyright to Australian Family Physician. Reproduced with permission. Permission to reproduce must be sought from the publisher, The Royal Australian College of General Practitioners.BACKGROUND: Vitamin D is essential for the normal functioning of a diverse range of metabolic processes, especially bone health. It is widely appreciated that the elderly are at increased risk of vitamin D insufficiency, but it is less well known that people with intellectual disability are also at increased risk. OBJECTIVE: This article summarises the issues regarding vitamin D in people with intellectual disability, making recommendations about screening, management and follow up. DISCUSSION: The prevalence of intellectual disability in the Australian population has been estimated at just over 1%, implying that most general practitioners will care for several people with intellectual disability. Relatively simple steps are likely to have a significant impact on the health of this vulnerable group of people.Simon Vanlint, Michael Nugent and Seeta Durvasul

Downs, J.

Durvasula, S.

Leonard, H.

Nugent, M.

Vanlint, S.

Adelaide Research &amp; Scholarship

348  Reprinted from AustRAliAn FAmily PhysiciAn Vol. 37, No. 5, May 2008 clinicAl PRActice  the effects of vitamin D deficiency have been recognised for centuries. however, it is a historical accident that vitamin D was classified as a vitamin, as vitamin D3 (cholecalciferol) is a fat soluble steroid hormone. Dietary vitamin D is absorbed in the small intestine and can be obtained from fish oils, liver, eggs, margarine and some dairy products. however, for most people at most times, synthesis of vitamin D in the skin is the most important source. it has been suggested that sunscreen use may interfere with vitamin D synthesis, but local data suggest that during an Australian summer sufficient sunlight is received by regular sunscreen users to produce vitamin D.1 Vitamin D promotes calcium and phosphate absorption by the small intestine, mineralisation of the skeleton and maintenance of extracellular calcium levels. Severe vitamin D deficiency may result in rickets or osteomalacia, rarely seen in modern Australia. However, osteoporosis and the consequent increased fracture risk can also result from vitamin D deficiency.  There are several new areas of interest in vitamin D. Vitamin D receptors are virtually ubiquitous in human tissue, and so perhaps not surprisingly, vitamin D deficiency has been linked with cancer mortality (colon, prostate, breast, ovary, pancreas), increased risk of autoimmune disease, abnormal lung function (including chronic obstructive pulmonary disease), tuberculosis, disorders of glucose metabolism, and psychiatric illness.2 More tenuous associations have been proposed with detrusor instability, swallowing disorders and age related macular degeneration. Epidemiologic observational studies suggest associations, but do not prove causality, and further study is ongoing.3–5  Who is at risk?Certain individuals are at increased risk of vitamin D deficiency, the most widely recognised being the elderly, especially those in residential care institutions.6 This is largely due to immobility resulting in limited sunlight exposure, and is exacerbated by the reduced ability of elderly skin to synthesise vitamin D even when exposed to sunlight. Background Vitamin D is essential for the normal functioning of a diverse range of metabolic processes, especially bone health. It is widely appreciated that the elderly are at increased risk of vitamin D insufficiency, but it is less well known that people with intellectual disability are also at increased risk. ObjectiveThis article summarises the issues regarding vitamin D in people with intellectual disability, making recommendations about screening, management and follow up. Discussion The prevalence of intellectual disability in the Australian population has been estimated at just over 1%, implying that most general practitioners will care for several people with intellectual disability. Relatively simple steps are likely to have a significant impact on the health of this vulnerable group of people.Vitamin D and people with intellectual disability  simon Vanlint MBBS, FRACGP, Lecturer and Assistant Dean (Students), Discipline of General Practice, University of Adelaide, South Australia. simon.vanlint@adelaide.edu.aumichael nugent MBBS, BMedSci(Hons), is Senior Medical Officer, Centre for Intellectual Disability Health, Adelaide, South Australia.seeta Durvasula MBBS, MPH, MPaed, DCH, is Lecturer, Centre for Developmental Disability Studies, University of Sydney, New South Wales.Reprinted from AustRAliAn FAmily PhysiciAn Vol. 37, No. 5, May 2008  349People with intellectual disabilityIt is less well known that people with intellectual disability (ID) are also at high risk of vitamin D deficiency, with local studies suggesting a prevalence of 50–60% in this group.7 It is likely that the most important factor is reduced mobility. Time constraints of carers may limit the opportunities for people with ID to be exposed to sunlight, as may concerns over the hazards of excessive exposure. Reduced mobility is compounded by the association between anticonvulsant use and reduced vitamin D levels. Epilepsy prevalence may be as high as 26% in people with ID, and difficulties with seizure control make polypharmacy more likely.8 There is some evidence that the older anticonvulsants (eg. phenytoin, phenobarbitone) are more likely to be implicated, and that use of multiple anticonvulsant medications is more problematic than monotherapy.9 People with ID have an increased risk of falls for many reasons, eg. reduced balance and coordination associated with the underlying cause of ID such as the spasticity associated with cerebral palsy,10 and visual impairment, which affects up to 20% of people with ID.11 Vitamin D deficiency has been shown to be associated with an increased risk of falls due to effects on muscle, and if prolonged and severe, can cause a true myopathy.12 Other conditions with a negative effect on bone health also occur in people with ID. The prevalence of coeliac disease, which causes calcium malabsorption, is increased in people with Down syndrome.13 Hypogonadism, which increases the risk of osteoporosis, is also more common in Down syndrome and ubiquitous in Turner syndrome.14,15 Women with ID may be long term users of depot progesterone only contraceptives, both for menstrual control and contraception.16 Such preparations have been associated with reduced bone density, and although it appears that this is largely reversible after cessation in short to medium term users, the effects in long term users are not clearly defined.17 It is important in all such individuals to be aware of these possible effects on bone health. The fracture rate in people with ID appears to be higher than that of the general population. Australian studies involving both community dwelling and institutionalised participants have found it to be 2–4 times higher;7,15,18 consistent with the international literature.7skin synthesis of vitamin D Where possible, it is probably best to promote adequate skin synthesis of vitamin D via sunlight exposure. Table 1 details suggested sunlight exposure times for different geographic locations. These recommendations19 attempt to balance the need for vitamin D synthesis with the known harmful effects of ultraviolet light, but as yet have not been substantiated by formal trials. It is likely that time spent outdoors, especially if combined with mobility and exercise, will have the beneficial effects of an enriched lifestyle above and beyond the simple production of vitamin D. testing of vitamin D levels Given the high prevalence of vitamin D deficiency, routine testing of 25-hydroxyvitamin D (25D) levels is appropriate in most, if not all, people with ID. There is broad agreement that 25D levels should exceed 50 nmol/L,20 with some suggesting that a threshold level of 60–70 nmol/L may be more appropriate.2 Seasonality is important, especially in the more mobile, with levels tending to be at their lowest in late winter/early spring, and peaking in late summer/early autumn.6 If vitamin D deficiency is found and treated, or the dose of an established treatment is altered, 25D levels should be checked 3–4 months later. A further check 12 months later should be sufficient to guarantee adequate levels in the future, unless there is a change in health or lifestyle status. There is no published evidence base for these recommendations; they were derived by expert consensus with an understanding of the underlying physiology. supplementation Where adequate sunlight exposure is not possible or has not resulted in adequate 25D levels, supplementation should be used. Vitamin D3 is preferable to vitamin D2, as it appears to be more Jenny Downs PhD, is Senior Research Officer, Centre for Child Health Research, University of Western Australia.helen leonard MBChB, is Clinical Associate Professor, Centre for Child Health Research, University of Western Australia.Table 1. Recommended sun exposure by location and season16 December – January July – AugustCairns (QLD) 6–7 mins 9–12 minsBrisbane (QLD) 6–7 mins 15–19 minsPerth (WA) 5–6 mins 20–28 minsSydney (NSW) 6–8 mins 26–28 minsAdelaide (SA) 5–7 mins 25–38 minsMelbourne (VIC) 6–8 mins 32–52 minsHobart (TAS) 7–9 mins 40–47 minsAuckland (NZ) 6–8 mins 30–47 minsChristchurch (NZ) 6–9 mins 49–97 minsNote: This table assumes the following: moderately fair complexion, exposure of the face and either the arms or legs, exposure before 10 am or after 2 pm (during daylight saving: before 11 am or after 3 pm)Vitamin D and people with intellectual disability  clinicAl PRActice350  Reprinted from AustRAliAn FAmily PhysiciAn Vol. 37, No. 5, May 200812. Montero-Odasso M, Duque G. Vitamin D in the aging musculoskeletal system: An authentic strength-preserving hormone. Mol Aspects Med 2005;26:203–19.13. Dias J, Walker-Smith J. Down’s syndrome and coeliac disease. J Pediatr Gastroenterol Nutr 1990;10:41–3.14. Foster B, Walkley J, Temple V. Bone mineral density status of women with intel-lectual disability. Adapted Physical Activity Quarterly 2001;18:49–59.15. Center J, Beange H, McElduff A. People with mental retardation have an increased prevalence of osteoporosis: a population study. Am J Ment Retard 1998;103:19–28.16. Grover S. Menstrual and contraceptive management in women with an intellec-tual disability. Med J Aust 2002;176:108–10.17. Kaunitz A, Miller P, Montgomery Rice V, Ross D, McClung M. Bone mineral density in women aged 25–25 years receiving medroxyprogesterone acetate: recovery fol-lowing discontinuation. Contraception 2006;74:90–9.18. Downs J, Bebbington A, Woodhead H, et al. Early determinants of fractures in Rett syndrome. Pediatrics 2007; in press.19. Diamond T, Eisman JA, Mason RS, et al. Vitamin D and adult bone health in Australia and New Zealand: a position statement. Med J Aust 2005;182:281–5.20. Lips P. Which circulating level of 25-hydroxyvitamin D is appropriate? J Steroid Biochem Mol Biol 2004;89–90:611–3.21. Arnas L, Hollis B, Heaney RP. Vitamin D2 is much less effective than vitamin D3 in humans. J Clin Endocrinol Metab 2004;89:5387–91.22. Trivedi DP, Doll R, Khaw KT. Effect of four monthly oral vitamin D3 (cholecalciferol) supplementation on fractures and mortality in men and women living in the com-munity: randomised double blind controlled trial. BMJ 2003;326:469.23. Chapuy M, Arlot M, Duboeuf F, et al. Vitamin D3 and calcium to prevent hip frac-tures in the elderly women. N Engl J Med 1992;327:1637–42.24. Diamond T. Annual intramuscular injection of a megadose of cholecalciferol for vitamin D deficiency: efficacy & safety data. Med J Aust 2005;183:10–2.effective.21 Fracture prevention studies in the elderly suggest a dose of at least 800 IU/day in combination with adequate calcium (at least 1000 mg/day) is likely to be effective.22,23 For example, two tablets daily of Ostelin Vitamin D + Calcium would achieve this aim, at a cost of about $0.30 per day. Where moderate to severe deficiency is found, higher doses may be necessary for a period of time to normalise levels rapidly. While objective evidence is limited, a regimen of 4000 IU/day for 3–4 months may be required to achieve this. Reports of vitamin D toxicity are scarce, and have not been reported with doses of 4000 IU/day.2 Even 600 000 IU as an annual intramuscular ‘megadose’ is well tolerated.24 Toxicity cannot be caused by excessive sun exposure. Hypercalcaemia is the only contraindication to vitamin D supplementation, and calcium levels should be checked before supplementation. Although the literature is not entirely consistent, it is generally held that vitamin D should be given in combination with calcium, either through a suitable diet, or as a supplement. Regrettably, vitamin D supplementation is not funded by the Pharmaceutical Benefits Scheme.conclusion From being thought of as an endocrine hormone principally affecting bone, calcium and phosphate, vitamin D has become the subject of speculation and investigation in relation to a range of physiological processes and disease states. It is likely that a significant number of Australians with ID are vitamin D deficient. Greater awareness and more assertive management will have significant health and economic benefits to this group of people. Conflict of interest: none declared.References1. Marks R, Foley P, Jolley D, Knight K, Harrison J, Thompson S. The effect of regular sunscreen use on vitamin D levels in an Australian population. Results of a rand-omized controlled trial. Arch Dermatol 1995;131:415–21.2. Heaney RP. The Vitamin D requirement in health and disease. J Steroid Biochem Mol Biol 2005;97:13–9.3. Parekh N, Chappell RJ, Millen AE, Albert DM, Mares JA. Association between vitamin D and age-related macular degeneration in the Third National Health and Nutrition Examination Survey, 1988 through 1994. Arch Ophthalmol 2007;125:661–9.4. Andersson KE. LUTS treatment: future treatment options. Neurourol Urodyn 2007;26(6 Suppl):934–47. 5. Katsanos KH, Nastos D, Noussias V, Christodoulou D, Kappas A, Tsianos EV. Manometric study in Kearns-Sayre syndrome. Dis Esophagus 2001;14:63–6.6. Morris H, Morrison G, Burr M, Thomas D, Nordin B. Vitamin D and femoral neck fractures in elderly South Australian women. Med J Aust 1984;140:519–21.7. Vanlint S, Nugent M. Vitamin D and fractures in people with intellectual disability. J Intellect Disabil Res 2006;50:761–7.8. McGrother CW, Bhaumik S, Thorp CF, Hauck A, Branford D, Watson JM. Epilepsy in adults with intellectual disabilities: prevalence, associations and service impli-cations. Seizure 2006;15:376–86.9. Petty S, Paton L, O’Brien T, et al. Effect of antiepileptic medication on bone mineral measures. Neurology 2005;65:1358–63.10. Glick NR, Fischer MH, Heisey DM, Leverson GE, Mann DC. Epidemiology of frac-tures in people with severe and profound developmental disabilities. Osteoporos Int 2005;16:389–96.11. Lennox N, Bain C, Rey-Conde T, Purdie D, Bush R, Pandeya N. Effects of a com-prehensive health assessment programme for Australian adults with intellectual disability: a cluster randomized trial. Int J Epidemiol 2007;36:139–46. CORRESPONDENCE afp@racgp.org.au

Vitamin D and people with intellectual disability

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Vitamin D and people with intellectual disability

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Vitamin D and people with intellectual disability

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Adelaide Research & Scholarship