Clinical Nutrition CH 18 Osteoporosis
What is osteoporosis?
-An age related disorder involving a DECREASE in the amt of bone to such a critical level that bones become susceptible to fractures w/ a minimal trauma
What vitamin deficiencies are involved in are involved with osteopenia?
-Calcium -Vit D -Magnesium -other vitamin deficiencies
What is osteocalcin and where does it originate?
-It is considered a marker of bone formation (circulatin osteoclacin) -It orginates from oestoblast activity
What is osteopenia? What is it a risk factor for?
-Thinning of bone mass -Developing osteoporosis
What is bone mineral density? (BMD)
-a measure of bone density -reflects the strength of bones as represented by their calcium content
Describe BMD measures
-non invasive -painless -procedure is usually done on the hips, spine, wrist, finger, shin bone, or heel
What do osteclast do?
-remove discrete sections of bones -they are bone-resorbing cells
What do osteblast do?
-replace new bone -they are bone-forming cells
What is the active form of Vitamin D and the primary source of calcium?
1,25-dihydroxycholecalciferol The conversion of vit d to the active form mentioned above is reduced in the elderly, affecting calcium absorption
What 2 things can decrease VIT C levels in the blood and may predispose an individual to osteoporosis?
1. AGING 2. SMOKING
WHat are the 2 form supplemental calmium comes in
1. Calcium carbonate 2. Calcium citrate
What 2 reasons results in an accelerated bone loss in women?
1. Deficiency in female hormone estrogen by menopause 2. Removal of the ovaries At menopause women undergo an accelerated rate of bone loss (2-3% yearly) for a subsequant decade plus there is a age related bone loss that is occuring as well. Bone loss begins to decrease for 8-10 yrs until its at the rate of premenopausal bone loss rates
What hormone is the PRIMARY circulating estrogen in postmenopausal women? Where does this hormone orginate from?
1. Estradiol 2. Ovary
What hormone is the primary estrogen in POSTmenopausal women? Where is this hormone synthesized in?
1. Estrone 2. Mainly in ADIPOSE and Muscle Tissues
What 2 organs are involved in the HYDROXYLATION of the vitamin and the conversion to its metabolically active form?
1. Liver 2. Kidney This conversion is needed to facilitate the intestinal absorption of calcium Sunlight Exposure and Vit D intake must be adequate for organs to be efficient in conversion
What are 2 skeletal disorders related to nutrition?
1. Osteoporosis 2. Osteomalacia
What major componets in sodas inhibit interfere with calcium utilization
1. Phosphoric acid 2. Caffeine- caffeine inhibits calcium absorption
Who is osteoporosis most common in?
1. Postmenopausal women 2. Elderly persons of BOTH sex
Deficiency of what 2 things can lead to impaired bone deposition?
1. Vit D 2. Calcium
What races are at the greater risk for osteoporosis? What are the additional risk factor characteristics?
1. White and Asian WOMEN (North European Wmen included) 2. An above especially having a small stature and being proportionally underweight for their height
Describe recommended amounts of calcium by age and sex
1. Women- 1000 mg/day 2. Individuals older than 51 years old- 1200mg/day
What 2 bone estrogen recpetors are present in bone cells?
1. estrogen receptor alpha and estrogen receptor beta (ER a & ER b)
What is a result of hypomagnesium in relation to calcium
1.Causes HYPOCALCEMIA 2. Peripheral resistance to the effects of vit D 3. Resistance to the effects of PTH Overall normal serum levels of magnesium are necessary for proper calcium metabolism If there is not proper magnesium level than adequate calcium intake may not be enough for proper bone health
In 1995, what was the annual cost of treating osteoporois and osteoporosis -related fractures in the US?
13.8 BILLION
What % of NONCOLLAGENOUS protein does osteocalcin account for in the bone?
15-20%
What is the recommended calcium to phosphorous ratio?
1:2 or 2:1 For every 1 calcium you should have 2 phosphorus or for every 2 calcium you should have 1 phosphorous
What fraction of Magnesium is present in the skeleton?
2/3 (two-thirds)
How many ppl over the age of 45 are affected by osteoporosis in the US?
20-25 million ppl
How many ppl worldwide suffer from osteoporosis?
200 MILLION worldwide
What is the peak age of bone mass?
25-30 years During the above ages, the individual remains on calcium balance and after calcium absorption exceeds bone accretion (lose bones- .3%-.5% yearly) in both men and women Linear growth of bones occurs up until the age of 18
What % of all postmenopausal women in U.S. and in Europe have osteoporosis? What is the % of the ages of these women and men?
30% At least 40% of these women and 15-30% of men are over 50 yrs of age and WILL sustain 1 or more fractures in their lifetime
What % of women btw ages 70 and 79 and women at 80 yrs of age will develop osteopososis WITHOUT medical intervention?
30% & 70% respectively
What % of hospilized patients over 65 yrs old have been diagnosed with a bone fracture ?
5.3% The above % will increase to 10.2% in patients over 85 years of age
What % where men and women found to have a lower risk of hip fracture in the HIGHEST quartile than those with dietary vitamin intakes in the LOWEST quartile?
65% of men and women were found to have a lower risk of hip fractures with vit k intakes in the highest quartile
What increased intake (exceeding RDA amts) is know to increase urinary excretion of calcium?
A high protein intake -It cause a hypercalciuric effect Proposed mechanism believe it is due to an increase GFR (glomerular filtration rate) and reduced renal tubular reabsorption of calcium These are both said to increase excretion of calcium
What is essential for the efficient utilization of dietary calcium?
Adequate Vitamin D
What age do american girls stop getting enough calcium in their diet?
After the age of 11
How does the WHO define osteopenia?
As a condition in which bone density is BTW 1 SD and 2.5 SD below the the mean density of a normal young adult (SD-standard deviation)
How does the WHO define osteoporosis?
As a condition in which bone density is MORE THAN 2.5 SD below the mean
What ethnicity has a greater bone density and lower risk of fracture compared to White American?
BLACKS Black ppl have a greater bone and muscle mass
Why is osteoporosis considered a pediatric diseases with an geriatric outcome?
Bc being diagnosed with osteoporosis is based on early factors on maintaining healthy bones later in life
Why are women more prone to osteoporosis than men?
Bc of a women's low peak bone mass in adulthood and the dramatic impact of menopause on bone mass
Why do you women of all ages do not get enough calcium?
Bc of substitution of milk with Sodas Sodas have a negative effect of calcium utilization as well
Why is osteoporosis called a "silent disease"?
Because it gradually progresses over many yrs, often w/o symptoms
What measure can determine if a patient has osteopenia or osteoporosis and estimate the risk of bone fractures?
Bone mineral density (BMD)
How is osteocalcin synthesis increased? Describe it concentration in the bone
By vitamin D Its concentration in the bone is DIRECTLY proportional to the amount of CALCIUM in the bone
What is the active form of Vit D's other name?
Calcitriol also known as 1,25 dihydroxycholecalciferol
What does estrogen deficiency at menopause DECREASE?
Calcium Absorption This decrease in calcium absorption cause bone mass to decrease
Which calcium (calcium carbonate or citrate ) is BEST absorbed?
Calcium Citrate is Better absorbed and can be taken w/o food Calcium carbonate is simply cheaper and HAS TO be taken with food
Who do Z scores asses?
Children and young adults
What 2 things in combination are needed to strengthen bones, increase bone mass, and decrease fractures rates?
Combination of CALCIUM & VITAMIN D
What is the time frame for the entire remoelding sequance?
Completed btw 4-5 Months
What is the most commonly recognized BMD test? What 5 things can it do?
DEXA test (Dual X-ray absorptiometry test) 1. Detect bone density before a fracture occurs 2. Confirm the diagnosis of osteoporosis 3. Predict the chance of fracture in the future 4. Determines an individuals rate of bone loss 5. Monitor the effects of treatment
What hormone inhibits PTH action?
ESTROGEN There is a reduction in estrogen in postmenapausal women
What does etrogen inhibit?
Estrogen inhibits the action of PTH, and PTH increases bone resorption
T or F, weight loss in women around menopause is NOT associated with an increased loss of bone density?
FAlSE, it is Supplementary calcium helps to reverse this phenomenon
What is circulating undercarboxylated osteocalcin predictive of?
FRACTURE RISK
What trait is localized to chromosome 11q12-13?
HBM (high bone mass trait) It is due to a systemic change in the beta protien module of the LDL receptor related protiein, this gene and mutation discovered where identified to be nature's cure for osteoporosis.
Who is circulating levels of undercarboxylated oestocalcin found to be higher in? What AGE is it higher in?
HIGHER IN POSTMENOPAUSAL women then premenopausal women Higher in women OVER the age of 70
What is osteomalacia?
Inadequate bone mineralization due to Vitamin D deficiency
What results in HIGHER peak bone density???
Increased CALCIUM intake during growth and early adult hood Those who consumed a high level of calcium had both a greater skeltal mass and relatively fewer hip fractures than those who consumed lower levels of calcium
Vitamin K deficiency may be related to what skeletal impairment?
Increased skeletal fragility Vit K supplementation (45mg/day) in women 40-78 found lower fractures in: Vertebral- 60% Hip- 77% Nonvertebral- 81%
What does a T score compare?
It compares a patients bone density to to that of a mean value of young Caucasian of the same gender
What does a Z score compare?
It compares the patient's bone density to the mean value of a matched populaton in terms of age, sex, and ethnicity. For both T and Z scores the MORE NEGATIVE the score 1. The greater the severity of the disease 2. The greater one's risk of fracture
What does PTH increase?
It increases 1. bone resorption leading to bone loss
What sugar has a beneficial effect on calcium absorption?
Lactose
Where is Magnesium in bone located?
Located in the CRYSTAL SURFACE of bone NOT part of hydroxyapatite lattice structure
What increases the secretion of PTH (parathyroid hormone)?
Low level of SERUM calcium PTH acts on the bone and releases calcium into circulation
What is common in the elderly in relation to Vit D.
Low levels of circulating VIT D
Who do T scores asses?
Men over the age of 50 and postmenopausal women
What causes an increase PTH production?
Mild Vitamin D deficiency
But what is adequate protein necessary for?
Necessary to REDUCE BMD loss and the risk of fracture, especially in older women
Name a VIT K-dependent protein that is produced by osteoblast during bone matrix formation. This protein also appears in bones after hydroxyapatite deposition
OSTEOCALCIN
What is specific to osteomalacia that makes it unique from osteoporosis?
Osteomalacia has a LOWER bone calcium to protien ratio than osteoporosis
What is the time frame for bone REPLACEMENT?
Over the course of several months
What is the time frame for bone RESORPTION?
Over the course of several weeks
Who is ostepenia commonly seen in?
People over the age of 50 who have lower than avg bone density AND who DON'T have osteoporosis
What supplementation decreases bone loss and reduces urinary calcium excretion in age 55-75 yr old population?
Phylloquinone (1mg/day)
Estrogen in combination of what other hormone presents loss at the hip and spine and reduces hip fracture rates?
Progestin
What is Positively associated w/ BMD? What is Negatively associated w/ BMD?
Serum 1,25-dihydroxy cholecalciferol is POSITIVELY associated with BMD PTH is NEGATIVELY associated with BMD
What chemical is released during the activity of osteoclasts and bone resorption?
TRAP (Tartrate -resistant acid phosphatase) Its serum levels provide informaation about the activity of osteoclast
T or F, excess weight and obesity reduce the risk of developing osteoporosis?
TRUE
T or F, ppl who suffer from hip fractures have a 12%-20% higher mortality rate than person of the same sex and similar age without fractures.
TRUE
T or F, ppl with lower body weight have lower body mass density?
TRUE
T or F, more than 1.5 million Americans have fractures
TRUE 700,000 Vertebral fractures 250,000 Hip fractures 250,000 Wrist fractures
What is a KEY difference btw osteoporosis and osteopenia?
The measure of BONE DENSITY
What mechansum ensure suffeicnt calcium in the blood?
The parathyroid gland senses low serum calcium levels and therefore releases PTH hormone to increase bone resorption which ensures sufficient calcium in the blood
T Or F those with greater bone mass at peak maturity (a denser skeleton) will take longer to reach the critically reduced level of bone mass
True
T or F, do higher amts of body fat protect against bone loss? Why or Why not?
True Body fat is a nonovarian source of circulating estrogen, and influences the rate of bone loss by higher amounts of body fat protecting against menopausal bone loss
Name 2 types of osteoprosis
Type 1 -Postmenopausal -occurs in women BTW age 48 and 55 yrs old -due to estrogen deficiency Type 2 -Occur in both Men and Women OVER 70 -Bone loss is not accelerated at any specific age but instead occurs as a slow, steady rate over many yrs.
How does Vit C cause osteoporosis?
Vitamin deficiency impairs COLLAGEN synthesis, since there is a lack if this mineral during bone formation The ability to form mature collagen fibers is lacking due to defective hydroxylation of proline bc of vit C deficiency
Describe the incidence of osteoporosis btw men and women and ethnic groups?
Women have a GREATER incidence (twice as much) of osteoporosis than men Osteoporosis is more common in Caucasian women than in black ppl and other ethnic groups
What kind of scores are used to compare a patients BMD results?
Z and T scores
