This disorder results in the bones becoming brittle and fragile through the loss of bone tissue. When a reduction in bone mass becomes sufficient to impede normal function of the bones, a person is said to have Osteoporosis.
Cause and Effect
Osteoporosis arises as a result of the imbalance between bone degradation/re-absorption and bone formation, controlled in the body by osteoclasts and osteoblasts respectively (see Bone Repair). The bones are degraded by osteoclasts, but not re-formed by the osteoblasts, causing the bones to become porous, brittle and susceptible to fractures. The factors causing osteoporosis can be split in to three groups – Non-modifiable, Modifiable and Disease.
- Non-modifiable – The main factor, and the one which causes the most cases of osteoporosis, is ageing. The sex hormones (oestrogen in women, testosterone in men) play a large role in the maintenance of normal rates of bone deposition. The level of sex hormones in the body drops as people age, resulting in the rate at which bones re-form becoming insufficient to maintain the bone's structural integrity. Osteoporosis is more prevalent in women as the levels of sex hormone decreases at an earlier age (during menopause) than in men. Oestrogen has also been shown to have a greater effect on the rate of bone re-formation than testosterone. Osteoporosis resulting from non-modifiable factors, such as menopause or ageing, is referred to as Type one or Primary Osteoporosis.
- Modifiable – Some forms of osteoporosis can be prevented or have their symptoms reduced by modifying certain things. These factors are therefore called modifiable factors. People can often reduce the risk of developing osteoporosis by taking in to account these modifiable factors. Some of these are:
Malnutrition – This factor is of detrimental effect to the bone in a number of different ways:
- Calcium deficiency: This causes the body to strip more calcium from the bones than is safe to do so, in order to supply its daily needs.
- Insufficient energy: The poor diet results in an overall slowing down of metabolic processes of the body, due to the lack of energy. The bone re-forming properties of the osteoblasts can be slowed down and in some severe cases stopped.
- Oestrogen drop: Malnutrition can result in a female losing her period. This amenorrhea (loss of menstrual cycle) can cause a drop in oestrogen levels, which as stated previously, causes a dangerous imbalance in osteoblasts and osteoclasts.
- Vitamin D deficiency: A drop in vitamin D in the body has been linked to an increase in the presence of Parathyroid Hormone (PTH), which increases the amount/rate of bone re-absorption.
Alcoholism – Drinking excessive amounts of alcohol regularly, especially at a young age, can increase your risk of developing osteoporosis. Alcoholism can cause a number of problems:
- PTH Increase: In the same way that a vitamin D deficiency can increase the levels of parathyroid hormone, regularly drinking excessive alcohol can do the same. Alcohol raises the level of PTH in the body, increasing the amount of calcium re-absorption, for a prolonged period of time.
- Poor Calcium Uptake: Alcohol can damage the enzymes in the liver which are responsible for converting the inactive form of vitamin D into the active form. Without the active form of vitamin D, calcium cannot be absorbed into the body properly, increasing the need for calcium re-absorption from the bone.
- Increase in Cortisol: Regular excessive drinking can increase the levels of cortisol in the body (the stress hormone). Cortisol increases the efficiency of osteoclasts, whilst decreasing the efficiency of the osteoblasts, resulting in osteoporosis.
Smoking – This can lead to osteoporosis in two ways:
- Osteoblast inhibition: Smoking can inhibit osteoblasts, therefore decreasing the amount of bone formation and repair. The osteoclasts are not inhibited, meaning that calcium is removed from bones (weakening them) and not restored.
- Lowering oestrogen: In women, smoking can cause the breakdown of exogenous oestrogen, which is crucial for the maintenance of the osteoblast/osteoclast balance.
Over exercise – Excessive exercise can lead to constant damage to the bones, which leads to the exhaustion of the materials required for bone repair (osteoblasts). In women, excessive exercise can also lead to a decrease in the body’s oestrogen levels, resulting in a dangerous imbalance between the osteoblasts and osteoclasts.
- Disease – Osteoporosis can arise as a direct result of a particular disease, or as a side effect from a drug used to treat a disease. An extensive list of diseases and drugs that can lead to Osteoporosis can be found via the link below.
Osteoporosis caused by Modifiable factors or Disease/Disorder factors is referred to as Type 2 or Secondary Osteoporosis.
Osteoporosis can be identified through the use of X-ray, but only at a developed stage. In order to detect osteoporosis in a bone that appears normal in an X-ray, a special form of bone density scanning must be used. Dual-energy X-ray Absorptiometry (DEXA) uses two low dose photon X-rays to scan the body and compare the levels of absorption. If the level of absorption passes below a certain level, a person is likely to be diagnosed with osteoporosis.
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The type of treatment prescribed for osteoporosis depends on the cause of the disorder. Most forms of osteoporosis can be treated or prevented through the use of calcium supplements, which reduce the need of the body to remove calcium from bones, weakening their structure. Some more specific treatments are:
Altering Modifiable Factors: Stopping harmful practices such as smoking, excessive drinking and poor diet, are always advised if relevant.
Oestrogen supplements: In cases where the main cause is a drop in oestrogen levels (such as after menopause), oestrogen supplements can be prescribed.
Treating reversible causes: If osteoporosis is a side effect of another disease or disorder, then through treating the main disease or disorder osteoporosis is itself being treated.
Fig.1 – Courtesy of Glitzy queen00