defficiency states of
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Defficiency states of. VITAMIN D. dr mukesh kumar. What is Vitamin D?. Vitamin D is a fat-soluble pro-hormone Sterol derivative 2 forms of vitamin D Vitamin D2 (Ergocalciferol) Vitamin D3 (Cholecalciferol) Pro-hormone is converted into its biologically active metabolite: calcitriol - PowerPoint PPT PresentationTRANSCRIPT
Defficiency states of
dr mukesh kumar
VITAMIN D
What is Vitamin D?
• Vitamin D is a fat-soluble pro-hormoneo Sterol derivative
• 2 forms of vitamin Do Vitamin D2 (Ergocalciferol)o Vitamin D3 (Cholecalciferol)
• Pro-hormone is converted into its biologically active metabolite: calcitriol
• Vitamin D may be obtained from the diet and through skin exposure to sunlight (UV light)
Uses for Vitamin D
• Maintains structural integrity of bones & bone growth by regulating use of calcium + phosphate (bone turnover)
• Maintains serum calcium homeostasis
• Research shows that Vitamin D may play a role in immune function and protection from chronic diseases
Synthesis and Metabolism
• Ergocalciferol (D2) synthesized in plant and fungi when ergosterol undergoes photolysis under UV light
• Cholecalciferol (D3) synthesized in skin of animals by photolysis of 7-dehydrocholesterol
• Bioactivation occurs through 2 steps• Hydroxylation in liver produces calcidiol• Hydroxylation in kidney produces calcitriol
Mechanism of Action• Calcitriol is transported through the circulatory
system by vitamin D binding protein and albumin
• Diffuses into the nucleus of target cells and binds to Vitamin D receptor (VDR)
• VDR associates with Retinoic Acid X receptor (RXR) – forms VDR-RXR complex
• VDR-RXR binds to DNA sequences called Vitamin D Response Elements (VDREs) to modulate the expression of >50 genes
Mechanism of Action
• VDRE regulated gene expression leads to:
o Increased dietary calcium and phosphorus absorption in small intestine
o Increased renal reabsorption of calcium
o Increased renal excretion of phosphate
o Increased resorption of bone to increase serum calcium levels
Natural Food Sources:Egg Yolk 20-25/yolk
Shrimp 152/100gm
Tuna 224-332/100gm
Canned salmon 624/100gm
Natural Food Sources:Egg Yolk 20-25/yolk
Shrimp 152/100gm
Tuna 224-332/100gm
Canned salmon 624/100gm
Sources of Vitamin D- Food
Fortified Food Sources:
Vitamin D milk 400/L
Formula 400/L
Cereal 40/serving
Yogurt 89/100gm
Fortified Food Sources:
Vitamin D milk 400/L
Formula 400/L
Cereal 40/serving
Yogurt 89/100gm
Less than 10%!
Less than 10%!
Sources of Vitamin D - Sun
UV light converts cholesterol in skin into D3 Dark skinned people
require a longer duration of sun exposure for adequate production of Vitamin D
Less UV light is available in the winter months, higher latitudes, and with cloud cover and air pollution
Vitamin D sources
• Fortified foods (milk and orange juice)
• Fish liver oilo Cod liver oil contains over 1000IU/tablespoon
• Fatty fish (salmon, tuna)
• Liver, beef
• Sunlight exposureo 5-30 minutes in direct sunlight at mid-day
• Supplements
Recommended Dietary Allowances
Age group Recommended Dietary Allowance (RDA) per day
Tolerable Upper Intake Level (UL) per day
Infants 0-6 months 400 IU (10 mcg) * 1000 IU (25 mcg)
Infants 7-12 months 400 IU (10 mcg) * 1500 IU (38 mcg)
Children 1-3 years 600 IU (15 mcg) 2500 IU (63 mcg)
Children 4-8 years 600 IU (15 mcg) 3000 IU (75 mcg)
Children and Adults 9-70 years
600 IU (15 mcg) 4000 IU (100 mcg)
Adults > 70 years 800 IU (20 mcg) 4000 IU (100 mcg)
Pregnancy & Lactation 600 IU (15 mcg) 4000 IU (100 mcg)
*Adequate intake rather then RDARetrieved from Health Canada. (2010, December 13). Vitamin D and Calcium: Updated Dietary Reference Index
Why do breast fed babies need supplemental Vitamin D?
Breast milk contains little vitamin D 25-78 IU/day Rates of vitamin D deficiency
in breastfed infants up to 78% in winter
Limited sun exposure
: infants less than 6 months should be kept out of direct sunlight
Why do breast fed babies need supplemental Vitamin D?
High rates of Vitamin D maternal deficiency
Pittsburgh study at birth: Black women
29% deficient 54% insufficient
White women 5% deficient 42% insufficient
Preventing Vitamin D deficiency
Breastfed and partially breastfed infants should be supplemented with 400 IU/day of vitamin D beginning in the first few days of life.
Supplementation should be continued unless the infants is weaned to at least 1L/day of vitamin D-fortified formula or fortified milk.
TriViSol contains 400 IU per ml
Vitamin D Deficient States
Rickets Peak incidence 3-18
months Defective bone growth
due to lack of mineralization at growth plate
Hypocalcemic seizures Growth failure, lethargy,
irritability Delay in gross motor
development, bone pain
Vitamin D Deficient states
RicketsBowing or widening of physis
Costochondral beading (rachitic rosary)
Craniotabes
Delayed closure of anterior fontanel
Dental abnormalities
Flaring of ribs at diaphragm
Vitamin D Deficiency
• Inadequate exposure to sunlight (UV rays)
• Inadequate intake from diet
• Deficiencies in GI tract absorption
• Kidney or liver disorders
Retrieved from: http://emedicine.medscape.com/article/412862-overview
Rickets (children)
• Pathophysiologyo Rickets is failure of bone to mineralizeo Growth plates of bone continue to enlarge while
the load on the limbs continues to increase In the absence of mineralization, limbs become
bowed
• Symptomso Characterized by stunted growth and deformed
boneso In infants, rickets may result in the delayed closure
of fontanelles (soft spots on baby’s head)
Treatment
o Vitamin D and calcium supplementso Corrective surgery or bracing for skeletal
deformities
Vitamin D Deficient States
Adult Vitamin D deficiency implicated in Increased infections Autoimmune diseases (Multiple
Sclerosis, Rheumatoid arthritis) Cancer Type 2 Diabetes Bipolar disorder, schizophrenia
Type I Diabetes in childhood Maternal Vitamin D status associated
with adverse outcomes of pregnancy – miscarriage, preeclampsia, preterm birth
Osteomalacia (adult)
• Pathophysiologyo Impaired bone mineralizationo Adult bones are in constant state of turnover and
new bones are brittle and thin
• Symptomso Bone pain (lower spine, pelvis, hips, legs, ribs)o May result in muscle weakness
• Treatmento Vitamin D supplementso Treating conditions affecting vitamin D absorption
and metabolism
Osteoporosis• Pathophysiology
o Rate of bone loss is greater than rate of bone formation – gradual loss of bone mass
o Bone strength is compromised – increased risk of fracture
• Symptomso Non-specific chronic back paino Height losso Bone fractures occur more easily
• Treatment and Preventiono Maximizing/maintaining existing bone
mass density Calcium and vitamin D supplements,
weight-bearing exerciseo Minimize risk of falls
Laboratory diagnosis
Vitamin D status- 25(OH)-D levels•Deficiency <37.5 nmol/mL•Insufficiency 37.5-50 nmol/mL•Sufficiency>50 (?) nmol/mL
Severe deficiency states associated with:
Ca,PO4,
Alk Phos, PTH
Summary Slide
Vitamin D (fat-soluble, pro-hormone): ergocalciferol (D2) and cholecalciferol (D3)
• converted to active hormonal form, calcitriol by metabolism in liver and kidney
• Targets: bone, kidney and GI tract• Function: maintains serum calcium levels & integrity of bones growth
via calcium regulation
Deficiency – leads to rickets, osteomalacia and osteoporosis• Lack of calcium leads to impaired bone mineralization and loss of
bone mass• Treatment: Increase vitamin D and calcium intake, and increase bone
mass density