mysteriesofvitd2-110324050453-phpapp01

7/31/2019 mysteriesofvitd2-110324050453-phpapp01

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DR. AJAY H. KANTHARIA

M.D.CONSULTING PHYSICIAN & CARDIOLOGIST

CRITICAL CARE PHYSICIAN

HON. PHYSICIAN:

Saifee Hospital

Sir. H.N. Hospital

Smt. Motiben B. Dalvi Hospital


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Mysteries of Vitamin D


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What is Vitamin DIs it Vitamin ?Is it Hormone ?

Is it single molecule?


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What is Vitamin D ? There are two main source of Vitamin D (1) Diet

(a) Vitamin D2 (ergocalciferol) Plant source

(b) Vitamin D3. (cholecalciferol) Animal source

(2) Sunlight


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Exposure of skin to UVB light converts

Provitamin D3 to Previtamin D3 which gets converted

to Vitamin D3.


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After synthesis in the skin or ingestion through thediet, vitamin D3 is stored in the liver, adipose tissueand muscle, where it has a half-life of about 60 days.

It is converted into 25-hydroxyvitamin D3, 25 (OH)Din the hepatocytes , often called calcidiol. Onceconverted to calcidiol, there appears to be nodifference in their biologic activity


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Calcidiol is then converted in the kidney to1,25(OH)2D Calcitriol.

Although there are more than 40 vitamin Dmetabolites identified, the predominate effects ofvitamin D in the body are exerted through the

actions of1,25(OH)2D (calcitriol).


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What do we measure ?


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What do we measure ? Most assays for 25(OH)D cannot differentiate the two

distinct forms,

25(OH) D2 from 25(OH) D3, so the abbreviation25(OH)D is used.


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What do we measure ? The serum 25-hydroxyvitamin D , 25(OH)D level is the

best indicator of overall vitamin D status because thismeasurement reflects total vitamin D from dietaryintake and sunlight exposure, as well as the conversionof vitamin D from adipose stores in the liver


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How do we interpret the report ? Earlier report mentioned a normal range.


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How do we interpret the report ? Now it is classified as :


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How do we Interpret reportDeficiency:level less than 10 ng/mL (25 nmol/L)

Insufficient : level between 10 to 30 ng/mL (25 to 75

nmol/L).Sufficient ..more than 30 ng/ml (75nmol/L)


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Source of Vitamin D (1) Sunlight

The skin synthesizes vitamin D3 from7-dehydrocholesterol in response to ultraviolet Bradiation in sunlight. This synthetic processdepends on many factors, including latitude,altitude, time of year and day, weather, age, skinpigmentation type, clothing, activity and otheraspects of the environment.


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In Boston, from April to October at

12 PM EST an individual with type III skin, with 25.5%

of the body surface area exposed, would need tospend 3 to 8 minutes in the sun to synthesize 400IUof vitamin D.


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Conclusions: Although it may be tempting torecommend intentional sun exposure based on ourfindings, it is difficult, if not impossible to titrate onesexposure. There are well-known detrimental sideeffects of ultraviolet irradiation. Therefore, oralsupplementation remains the safest way for increasingvitamin D status.

( J Am Acad Dermatol 2010;62:929.e1-e9.)


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Source of Vitamin D (2) Diet :


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Deficiency.. Why ??


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Low Levels of Vitamin D Dark Skin

Obese

Poor Dietary intake Malabsorbtion

Poor Exposure to sunlight

Drugs Phynetoin, steroids


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Manifestations of Vitamin D Deficiency


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Manifestations of Vitamin D Deficiency


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Non Traditional Role of Vitamin D Lowers Blood Pressure

Lowers insulin Resistance

Lower Risk of Cancers Improves Immunity


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Vitamin D In CKD


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Subjects Within K/DOQI Target Ranges

CKD 3 n =

65 (%)

CKD 4 n =

113 (%)

Calcidiol sufficient (>30ng/mL)

29 17

Calcidiol insufficient

(1030 ng/mL)

57 58

Calcidiol deficient (


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Vitamin D in Myalgia


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Vitamin D in Myalgia due to Statin


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Vitamin D in Myalgia due to StatinA study was conducted with specific aim to determine

whether low serum 25 (OH) vitamin D (D2 + D3) (


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Vitamin D in Myalgia due to Statin Of the 82 vitamin- Ddeficient, 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 to48.2ng/mL (P , 0.0001) and resolution of myalgia in 35(92%).


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Recommended dosage


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Recommended dosage In healthy adults at low risk for vitamin D deficiency

(i.e., under age 50, without osteoporosis or conditionsaffecting vitamin D absorption or action), routine

vitamin D supplementation (1025 g [4001000IU]daily) is recommended.


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Recommended dosageAdults over 50 years of age who are at moderate risk for

vitamin D deficiency. Supplementation with at least2025 g (8001000 IU) of vitamin D3 daily is

recommended. To achieve optimal vitamin D status (>75 nmol/L), many individuals may requiresupplementation at greater than 25 g (1000 IU)daily


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Recommended dosage Doses up to 50 g (2000 IU) per day are safe and do

not require monitoring.


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Recommended dosage Treatment of severe deficiency (rickets or

osteomalacia) requires higher doses, e.g., 1250 g (50000 IU) daily for two to four weeks, then weekly or

biweekly, with monitoring of serum 25-hydroxyvitamin D at one and three months.


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Safety and toxicity of vitamin D

supplementation Excessive use of vitamin D supplements has the

potential to cause progressive accumulation and toxiceffects, presenting as hypercalcemia and renal damage.

Toxic effects occur only with prolonged (at least severalmonths) daily intake of more than 1000 g (40 000 IU)


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Vitamin D and Calcium


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Conclusion Sunlight is inadequate source of Vitamin D

Diet is inadequate source of Vitamin D

Diet fortified with Vit D is required. Calcium and Vitamin D are coprescribed

Vitamin D supplementation is essential and that too inhigher dosage than accepted till now.


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