DR. AJAY H. KANTHARIA M.D.

CONSULTING PHYSICIAN & CARDIOLOGISTCRITICAL CARE PHYSICIAN

HON. PHYSICIAN:Saifee HospitalSir. H.N. HospitalSmt. Motiben B. Dalvi Hospital

Mysteries of Vitamin D

What is Vitamin DIs it Vitamin ?

Is it Hormone ?

Is it single molecule?

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

Exposure of skin to UVB light converts Provitamin D3 to Previtamin D3 which gets converted to Vitamin D3.

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.

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

Calcidiol is then converted in the kidney to 1,25(OH)2D …… Calcitriol.

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).

What do we measure ?

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 abbreviation 25(OH)D is used.

What do we measure ?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

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

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

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)

Source of Vitamin D(1) Sunlight

The skin synthesizes vitamin D3 from 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.

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 to spend 3 to 8 minutes in the sun to synthesize 400 IU of vitamin D.

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.

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

Source of Vitamin D(2) Diet :

Deficiency….. Why ??

Low Levels of Vitamin DDark SkinObesePoor Dietary intakeMalabsorbtionPoor Exposure to sunlightDrugs… Phynetoin, steroids

Manifestations of Vitamin D Deficiency

Manifestations of Vitamin D Deficiency

Non Traditional Role of Vitamin DLowers Blood PressureLowers insulin ResistanceLower Risk of CancersImproves Immunity

Vitamin D In CKD

 Subjects Within K/DOQI Target Ranges

 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

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.

Vitamin D in Myalgia

Vitamin D in Myalgia due to Statin

Vitamin D in Myalgia due to StatinA 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.

Vitamin D in Myalgia due to StatinOf 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%).

Recommended dosage

Recommended dosage 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.

Recommended dosageAdults 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

Recommended dosageDoses up to 50 μg (2000 IU) per day are safe

and do not require monitoring.

Recommended dosageTreatment 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.

Safety and toxicity of vitamin D supplementation Excessive use of vitamin D supplements has

the potential to cause progressive accumulation and toxic effects, presenting as hypercalcemia and renal damage.

Toxic effects occur only with prolonged (at least several months) daily intake of more than 1000 μg (40 000 IU)

Vitamin D and Calcium

ConclusionSunlight is inadequate source of Vitamin DDiet is inadequate source of Vitamin DDiet fortified with Vit D is required.Calcium and Vitamin D are coprescribed Vitamin D supplementation is essential and

that too in higher dosage than accepted till now.