vitamin D Flashcards
Skin cancer is the most common form of cancer in the United States
true
why has photoprotection become contreversial?
We cannot protect the skin from the damaging effects of UVR without decreasing the formation of Vitamin D
UV action spectra for DNA damage, skin cancer and vitamin D photosynthesis is i________
identical
who is at risk for vit D deficiency? (DONE)
dark skin obesity northern latitudes obese
which form of vitamin D is used to determine a patient’s vitamin D status?
25-hydroxy vitamin D3
what is the right level of Vitamin D? levels for deficiency? insufficiency, sufficiency, and intoxication?
deficiency: <20ng/ml
insufficiency: 21-29 ng/ml
**sufficiency: >30ng/mL **
intoxication: >150 ng/mL
what are two sources of vitamin D we should be aware of?
Sunlight Most people get vitamin D from sun exposure
Diet Only
naturally occurring food that supplies substantial quantities of the vitamin is cold-water ocean fish Fortified foods (milk, OJ etc.) Vitamins
who is usually vitamin D deficienct?
Despite food fortification, deficiency remains common in children and adults with limited sun exposure
what is primary cause of low vit D status?
Decreased skin synthesis of vitamin D is widely accepted as primary cause of epidemic low vitamin D status worldwide
causes of reduced skin synthesis of vitamin D? (7)
season and latitude
skin pigment
aging
sunscreen and photoprotection
decreased bioavailability
heritable and acquired disorders
decreased synthesis
how does season and latitude reduce vit D synthesis?
Ozone filters out sunlight increases the amount of ozone UVB needs to passalmost all of UVB
Lower angle of incoming through to reach the earths surface
Very little if any vitamin D can be synthesized in the skin from November through February at latitudes north of 37 degrees
how does skin pigment reduce vit D synthesis?
Absorption of UVB by melanin reduces vitamin D synthesis by as much as 99%
how does aging reduce vit D synthesis?
Reduction of 7-dehydrocholesterol in the skin Reduces vitamin D synthesis by about 75% in a 70-year old
how do sunscreen and photoprotection reduce vit D synthesis ?
SPF 15 reduces vitamin D synthesis by 93% (if used correctly…)
how does decreased bioavailability reduce vit D synthesis?
Malabsorption Reduced fat absorption Obesity Vitamin D sequestered in body fat
decreased synthesis of vit D absorption?
Liver disease Renal disease
how does Vit D work? remember (PAAD)
Fat-soluble steroid hormone Exerts its biologic effects by binding to vitamin D specific receptors Found in most tissues and cells in the body Controls over 200 different genes Proliferation Differentiation Apoptosis Angiogenesis
vitamin D and PTH?
Acts with PTH to maintain normal levels of calcium and phosphate (increases intestinal absorption of Ca+, PO4, and Mg) -osteolytic effect on bone -decreased renal clearance
what is rickets? how is it treated?
Extreme and prolonged vitamin D deficiency Softening and weakening of bones Marked bending of bones, fractures, costochondral swelling tx:Conquered with food fortification
what are the manifestations of vitamin D deficiency?
Adults: Osteomalacia, Osteopenia, Osteoporosis(increased risk of fractures) Muscle weakness - increase risk of falls
individuals at higher latitudes are at increased risk for? (POP BLC)
Increased risk for lymphoma, colon, pancreatic, prostate, ovarian, breast and other cancers More likely to die from these cancers
Individuals with 25-hydroxyvitamin D levels below 20 ng/ml are at increased risk for___________?
30 to 50% increased risk of colon, prostate and breast cancer Higher mortality from these cancers
what are some diseases that may be more common at high altitudes?
Cardiovascular disease Hypertension, CHF Schizophrenia Depression Wheezing illnesses Autoimmune disease Diabetes, Crohn’s disease, rheumatoid arthritis, multiple sclerosis
t/fVitamin D obtained from the diet or supplements can fully substitute for vitamin D synthesized in the skin
t
KNOW: what are the two forms of vitamin D? which one is more readily absorbed?
Vitamin D2 (ergocalciferol - plant derived)
Vitamin D3 (cholecalciferol – fish derived)
Vitamin D3 is more readily absorbed than D2 More effective at maintaining serum 25-hydroxyvitamin D levels
above what level (ng/mL) is vitamin D toxic? what can too much vit D cause? how common is vit D toxication?
Serum 25-hydroxyvitamin D level above 150ng/ml
Hypercalcemia, hyperphosphatemia and/or metastatic calcification
Rare but may be caused by ingestion of excessively high doses of vitamin D
how much vit D would you have to consume for Vit D intoxication?
More than 50,000 IU per day
t/f. Doses of 10,000 IU of vitamin D3 per day for up to 5 months does not cause toxicity
true
KNOW: Excessive exposure to ultraviolet light will increase risk of __________
Excessive exposure to ultraviolet light will increase risk of skin cancer
KNOW: what is required for vit D synthesis in the skin?
UVL is required for vitamin D synthesis in the skin
KNOW: who is at most risk for vit D deficiency?
Individuals with limited exposure to UVL are at higher risk for vitamin D deficiency
which metabolic conditions and diseases are associated with vit D deficiency?
**Abnormal calcium and phosphorus metabolism: rickets, osteoporosis **
Possibly other diseases: cancer, diabetes, immune system
KNOW: how can ppl obtain vitamin D? what should you do with individuals at risk for vit D deficiency?
Vitamin D obtained from diet or supplements can fully substitute for vitamin D synthesized in skin
People can obtain ample vitamin D from a combination of diet, supplements, and incidental protected sun exposure
Individuals at risk for vitamin D deficiency due to decreased photosynthesis should receive vitamin D supplementation
t/f. you Continue to recommend photoprotection to prevent skin cancer.
TRUE
KNOW: who are lower risk vit D patients and how much vit D/day should they receive?
Lower risk patients
400 IU daily for infants
600 IU daily for children and adults
800 IU daily for elderly
KNOW: who are higher risk vit D patients? what should you consider doing?
Higher risk patients
Homebound, northern latitudes, winter, obesity, darker skin
Consider getting a vitamin D level
what is the active form of vitamid D?
1, 25 vitamin D3
