Mysteries of Vitamin D


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Mysteries of Vitamin D

  1. 1. DR. AJAY H. KANTHARIA M.D. <ul><li>CONSULTING PHYSICIAN & CARDIOLOGIST </li></ul><ul><li>CRITICAL CARE PHYSICIAN </li></ul><ul><li>HON. PHYSICIAN: </li></ul><ul><li>Saifee Hospital </li></ul><ul><li>Sir. H.N. Hospital </li></ul><ul><li>Smt. Motiben B. Dalvi Hospital </li></ul>
  2. 2. Mysteries of Vitamin D
  3. 3. What is Vitamin D Is it Vitamin ? Is it Hormone ? Is it single molecule?
  4. 4. What is Vitamin D ? <ul><li>There are two main source of Vitamin D </li></ul><ul><li>(1) Diet </li></ul><ul><ul><li>(a) Vitamin D2 (ergocalciferol) Plant source </li></ul></ul><ul><ul><li>(b) Vitamin D3. (cholecalciferol) Animal source </li></ul></ul><ul><li>(2) Sunlight </li></ul>
  5. 5. <ul><li>Exposure of skin to UVB light converts </li></ul><ul><li>Provitamin D3 to Previtamin D3 which gets converted to Vitamin D3. </li></ul>
  6. 6. <ul><li>After synthesis in the skin or ingestion through the diet, vitamin D3 is stored in the liver, adipose tissue and muscle, where it has a half-life of about 60 days. </li></ul><ul><li>It is converted into 25-hydroxyvitamin D3, 25 (OH)D in the hepatocytes , often called calcidiol . Once converted to calcidiol, there appears to be no difference in their biologic activity </li></ul>
  7. 7. <ul><li>Calcidiol is then converted in the kidney to 1,25(OH)2D …… Calcitriol. </li></ul><ul><li>Although there are more than 40 vitamin D metabolites identified, the predominate effects of vitamin D in the body are exerted through the actions of 1,25(OH)2D (calcitriol). </li></ul>
  8. 8. What do we measure ?
  9. 9. What do we measure ? <ul><li>Most assays for 25(OH)D cannot differentiate the two distinct forms, </li></ul><ul><li>25(OH) D2 from 25(OH) D3, so the abbreviation 25(OH)D is used. </li></ul>
  10. 10. What do we measure ? <ul><li>The serum 25-hydroxyvitamin D , 25(OH)D level is the best indicator of overall vitamin D status because this measurement reflects total vitamin D from dietary intake and sunlight exposure, as well as the conversion of vitamin D from adipose stores in the liver </li></ul>
  11. 11. How do we interpret the report ? <ul><li>Earlier report mentioned a normal range. </li></ul>
  12. 12. How do we interpret the report ? <ul><li>Now it is classified as : </li></ul>
  13. 13. How do we Interpret report <ul><li>Deficiency :level less than 10 ng/mL (25 nmol/L) </li></ul><ul><li>Insufficient : level between 10 to 30 ng/mL (25 to 75 nmol/L). </li></ul><ul><li>Sufficient ..more than 30 ng/ml (75nmol/L) </li></ul>
  14. 14. Source of Vitamin D <ul><li>(1) Sunlight </li></ul><ul><li>The skin synthesizes vitamin D3 from </li></ul><ul><li>7-dehydrocholesterol in response to ultraviolet B radiation in sunlight. This synthetic process depends on many factors, including latitude, altitude, time of year and day, weather, age, skin pigmentation type, clothing, activity and other aspects of the environment. </li></ul>
  15. 15. <ul><li>In Boston, from April to October at </li></ul><ul><li>12 PM EST an individual with type III skin, with 25.5% of the body surface area exposed, would need to spend 3 to 8 minutes in the sun to synthesize 400 IU of vitamin D. </li></ul>
  16. 16. <ul><li>Conclusions : Although it may be tempting to recommend intentional sun exposure based on our findings, it is difficult, if not impossible to titrate one’s exposure. There are well-known detrimental side effects of ultraviolet irradiation. Therefore, oral supplementation remains the safest way for increasing vitamin D status. </li></ul><ul><li>( J Am Acad Dermatol 2010;62:929.e1-e9.) </li></ul>
  17. 17. Source of Vitamin D <ul><li>(2) Diet : </li></ul>
  18. 19. Deficiency….. Why ??
  19. 20. Low Levels of Vitamin D <ul><li>Dark Skin </li></ul><ul><li>Obese </li></ul><ul><li>Poor Dietary intake </li></ul><ul><li>Malabsorbtion </li></ul><ul><li>Poor Exposure to sunlight </li></ul><ul><li>Drugs… Phynetoin, steroids </li></ul>
  20. 21. Manifestations of Vitamin D Deficiency
  21. 22. Manifestations of Vitamin D Deficiency
  22. 23. Non Traditional Role of Vitamin D <ul><li>Lowers Blood Pressure </li></ul><ul><li>Lowers insulin Resistance </li></ul><ul><li>Lower Risk of Cancers </li></ul><ul><li>Improves Immunity </li></ul>
  23. 24. Vitamin D In CKD
  24. 25.   Subjects Within K/DOQI Target Ranges Adapted from LaClair RE, Hellman RN, Karp SL, et al: Prevalence of calcidiol deficiency in CKD: a cross-sectional study across latitudes in the United States. Am J Kidney Dis 45:1026–1033, 2005.   CKD 3 n = 65 (%) CKD 4 n = 113 (%) Calcidiol sufficient (>30 ng/mL) 29 17 Calcidiol insufficient (10–30 ng/mL) 57 58 Calcidiol deficient (<10 ng/mL) 14 26
  25. 26. Vitamin D in Myalgia
  26. 27. Vitamin D in Myalgia due to Statin
  27. 28. Vitamin D in Myalgia due to Statin <ul><li>A study was conducted with specific aim to determine whether low serum 25 (OH) vitamin D (D2 + D3) (<32 ng/mL) was associated with myalgia in statin-treated patients and whether the myalgia could be reversed by vitamin D supplementation while continuing statins. </li></ul>
  28. 29. Vitamin D in Myalgia due to Statin <ul><li>Of the 82 vitamin- D–deficient, myalgic patients, while continuing statins, 38 were given vitamin D (50,000 units/week for 12 weeks), with a resultant increase in serum vitamin D from 20.4 to 48.2 ng/mL (P , 0.0001) and resolution of myalgia in 35 (92%). </li></ul>
  29. 30. Recommended dosage
  30. 31. Recommended dosage <ul><li>In healthy adults at low risk for vitamin D deficiency (i.e., under age 50, without osteoporosis or conditions affecting vitamin D absorption or action), routine vitamin D supplementation (10–25 μg [ 400–1000 IU ] daily) is recommended. </li></ul>
  31. 32. Recommended dosage <ul><li>Adults over 50 years of age who are at moderate risk for vitamin D deficiency. Supplementation with at least 20–25 μg ( 800–1000 IU ) of vitamin D3 daily is recommended. To achieve optimal vitamin D status (> 75 nmol/L), many individuals may require supplementation at greater than 25 μg (1000 IU) daily </li></ul>
  32. 33. Recommended dosage <ul><li>Doses up to 50 μg (2000 IU) per day are safe and do not require monitoring. </li></ul>
  33. 34. Recommended dosage <ul><li>Treatment of severe deficiency (rickets or osteomalacia) requires higher doses, e.g., 1250 μg (50 000 IU) daily for two to four weeks, then weekly or biweekly, with monitoring of serum 25-hydroxyvitamin D at one and three months. </li></ul>
  34. 35. Safety and toxicity of vitamin D supplementation <ul><li>Excessive use of vitamin D supplements has the potential to cause progressive accumulation and toxic effects, presenting as hypercalcemia and renal damage. </li></ul><ul><li>Toxic effects occur only with prolonged (at least several months) daily intake of more than 1000 μg (40 000 IU) </li></ul>
  35. 36. Vitamin D and Calcium
  36. 37. Conclusion <ul><li>Sunlight is inadequate source of Vitamin D </li></ul><ul><li>Diet is inadequate source of Vitamin D </li></ul><ul><li>Diet fortified with Vit D is required. </li></ul><ul><li>Calcium and Vitamin D are coprescribed </li></ul><ul><li>Vitamin D supplementation is essential and that too in higher dosage than accepted till now. </li></ul>