Vitamin D. Mrs Sophie Barnes FRCPath Consultant Clinical Scientist

Transcription

1 Vitamin D Mrs Sophie Barnes FRCPath Consultant Clinical Scientist

2 Learning objectives Biochemistry and physiology of vitamin D Causes and consequences of vitamin D deficiency Current and anticipated guidelines Imperial College Healthcare NHS Trust guidelines What tests for vitamin D are offered at Imperial? When and how should vitamin D be measured?

3 Biochemistry Physiology From: Holick, MF Review Vitamin D Deficiency NEJM July 2007

4 Gene transcription Increased Decreased Vitamin D receptor Ca-binding proteins (CaBP) Calcium pump Osteocalcin Alkaline phosphatase 24-Hydroxylase Parathyroid hormone 1- Hydroxylase Collagen Interleukin-2 -Interferon

5 Sources of vitamin D Skin exposure h in April October Diet

6 Vitamin D deficiency causes Latitude Sun exposure / sun screen Obesity Fat malabsorption Nephrotic syndrome Anti-convulsants / anti-retrovirals Chronic granulmatous disorders Primary hyperparathyroidism

7 Vitamin D deficiency - consequences Decrease in intestinal absorption Secondary hyperprathryoisim Phosphaturia Mineralisation defects Muscle weakness BMD? Falls? Fractures?

8 Holick Edit BMJ 2008

9 Vitamin D deficiency British 1958 cohort, > 45y age: <25 <40 <70 Winter/Spring 15.5% 46.6% 87.1% Summer/Autumn 3.2% 15.4% 60.9% Am J Clin Nutr 2007; 83: 860-8

10 Hypovitaminosis D in Great Britain Hypponen & Power Brit Birth Cohort 2007

11 Seasonal & Geographical prevalence Hypponen & Power Brit Birth Cohort 2007

12 Guidelines SACN due Nov 2014

13 RCPCH guidelines

14 NOS guidelines

15

16 ICHNT Guidelines Risk Factors Aging Season Sunblock use Clothing Institutionalisation Skin pigmentation Malabsorption Obesity Drugs Severe liver failure Nephrotic syndrome Chronic kidney disease

17 What tests are offered for Vitamin D at Imperial? Request When to use Results reported Vit D Vit D Patient has never had supplements. Patient is on D3 only. Total Vitamin D 25 Vit D D2/D3 Patient is on D2 Patient is on D2 and D3 Patient is on unknown vitamin D D2, D3 and total vitamin D

18 Abbott Architect on the Track

19 Abbott Architect on the Track

20 LC-MS/MS

21 ICHNT interpretation Deficiency <40 Replace vitamin D: prescribe loading dose Insufficiency Replete Possibly toxic >150 Consider referral and vitamin D replacement if: glucocorticoids. osteoporotic or osteopenic. Evidence of secondary hyperparathyroidism (N Ca, high PTH) Low Ca CKD stage 3/4: see renal guidelines. If replacement required: prescribe maintenance dose No replacement needed / continue present dose Check calcium: refer if high Checked on LC-MS/MS

22 Replacement Loading dose over three months 20,000 IU D3 (capsule) weekly for 12 weeks Consider 20,000 IU D3 (capsule) twice a week for 12 weeks if BMI > 30 kg/m 2, drugs 300,000 IU D2 IM x 2, 3 months apart if absorption concerns Maintenance dose IU D3 per day 25 ug tablet daily 1000 IU per day 20,000 IU D3 capsule every 2 weeks approx 1400 units per day

23 Vit D supplementation D3 im D2 im D2orally D3 orally Graph taken from presentation by Dr P Holloway, Source not stated

24 Calcium in Primary Care

25 Vitamin D in Primary Care

26 Imperial workload Imperial PCT

27 Minimum Retesting Intervals Vitamin D: no clinical signs and symptoms Vitamin D: D3 or D2 therapy for whatever clinical indication, where basal vitamin D adequate Vitamin D: D3 or D2 therapy for whatever clinical indication, where basal vitamin D low and where there is underlying disease that might impact negatively on absorption Vitamin D: calcitriol or alphacalcidol therapy Do not retest Do not retest, unless otherwise clinically indicated e.g. sick coeliac or Crohn's patient Repeat after 3 6 months on recommended replacement dose Do not measure vitamin D Consensus opinion of working group. Sattar et al, Lancet 2012; 379:95 96 & 379: Consensus opinion of working group Consensus opinion of working group

28 Thank you Sophie Barnes Consultant Clinical Scientist Duty Biochemist