100 because so much of it is lost in the urine and stool Osteoporosis - « porous bones » from the Greek, weakening of the bones - not that much of an issue for men up to the age of 60 but to women - linked to low dietary calcium - about 9M associated fractures worldwide, attributed to mostly women - hip fractures are very common ; wrist fractures are quite common as well - when the fractures are examined by radiographic means (XRays), it is about the same for men and women => for women it is a more severe issue - risk factors : short stature, underweight, early menopause, physical inactivity, alcoholism, smoking, excess caffeine, excess protein, excess fiber that tend to capture the calcium ions and drag them out of the body - the stature of these individuals wears down, the spine curves, scoliosis - the issue is the resorption (= loss of bone mass overall) for post-menopausal women : 1-5% per year (in males, 10-20 years later) - at ~5% per year, 1/2 of the bone mass is gone in ~14 years - rule of 70 : take the number 70 and divide by the % of change per time and the result is the length of time it will take to either double or halve (depending on whether the change is a decrease or an increase) the circumstance in question - e.g. how long to double the bone mass if it is increasing by 1% a year -> 70 years ; how long to to halve the bone mass if it decreases by 7% a year -> 10 years 6
- the consequences of a loss of 10% in bone mass : 170% increased risk of fractures - 165 000 hip fractures a year -> 17% die within 3 months, 27% die within one year due to complications of hospitalisation… Mechanism of calcium loss and gain - calcium, phosphate and HO- connect together by a series of complicated mechanisms to make bones and teeth (calcium apatite) -> this is the absorption process - the problem is resorption of bones : the material in bones is made soluble and is lost - bones made up of protein material - cells called osteoclast : liberate acid in their action, which is taking away the bone material, leaving behind a spot where there is less bone material - specific inhibitors of osteoclasts exist such as Fosamax (Alendronate) -> inhibit osteoclast from functioning => about 3% a year increase in bone mass, rather more specific to the hips - other studies have lead researchers that Fosamax causes jawbone problems (osteonecrosis of the jaw, jawbone death) => lawsuits have taken place (over 5000 lawsuits are pending regarding this issue) - there are other remedies for osteoporosis such as zometa -> 2 P units in it, less dosing, promising drug BUT some side effects for some women - the process of absorption is mediated through osteoblasts : matrix of protein and mineral material is put together by the body - once the bone has been put together by the protein material, the calcium is implanted by the osteoblast process Detection of bone mass - blood is more complicated to analyse - XRay, CT scan - the ones that work the best are non-invasive single or double photon absorptiometry -> on the wrist, and it seems to correlate quite well with the bone mass on the hip - average risk by calculation : FRAX => a graph tells us if we are in low, medium or high risk depending on many factors 7
You've reached the end of your free preview.
Want to read all 10 pages?
- Spring '11
- Sodium, Sodium chloride, Hip fracture