WHY DO BONES BECOME WEAK .

OSTEOPOROSIS

Osteoporosis is a bone disease that occurs when the body loses too much bone, makes too little bone, or both. As a result, bones become weak and may break from a fall or, in serious cases, from sneezing or minor bumps. Osteoporosis means “porous bone.” Viewed under a microscope, healthy bone looks like a honeycomb. When osteoporosis occurs, the holes and spaces in the honeycomb are much larger than in healthy bone. Osteoporotic bones have lost density or mass and contain abnormal tissue structure. As bones become less dense, they weaken and are more likely to break.

Symptoms

• Back pain, caused by a fractured or collapsed vertebra
• Loss of height over time
• A stooped posture
• A bone that breaks much more easily than expected

RISK FACTORS

• Sex. Women are much more likely to develop osteoporosis than are men.
• Age. The older you get, the greater your risk of osteoporosis.
• Race. You’re at greatest risk of osteoporosis if you’re white or of Asian descent.
• Family history. Having a parent or sibling with osteoporosis puts you at greater risk, especially if your mother or father fractured a hip.
• Body frame size. Men and women who have small body frames tend to have a higher risk because they might have less bone mass to draw from as they age.

Hormone levels – Osteoporosis is more common in people who have too much or too little of certain hormones in their bodies. Examples include:

• Sex hormones.Lowered sex hormone levels tend to weaken bone. The reduction of estrogen levels in women at menopause is one of the strongest risk factors for developing osteoporosis. Men have a gradual reduction in testosterone levels as they age. Treatments for prostate cancer that reduce testosterone levels in men and treatments for breast cancer that reduce estrogen levels in women are likely to accelerate bone loss.
• Thyroid problems.Too much thyroid hormone can cause bone loss. This can occur if your thyroid is overactive or if you take too much thyroid hormone medication to treat an underactive thyroid.
• Other glands.Osteoporosis has also been associated with overactive parathyroid and adrenal glands.

Dietary factors – Osteoporosis is more likely to occur in people who have:

• Low calcium intake. A lifelong lack of calcium plays a role in the development of osteoporosis. Low calcium intake contributes to diminished bone density, early bone loss and an increased risk of fractures.
• Eating disorders. Severely restricting food intake and being underweight weakens bone in both men and women.
• Gastrointestinal surgery. Surgery to reduce the size of your stomach or to remove part of the intestine limits the amount of surface area available to absorb nutrients, including calcium. These surgeries include those to help you lose weight and for other gastrointestinal disorders.

Steroids and other medications – Long-term use of oral or injected corticosteroid medications, such as prednisone and cortisone, interferes with the bone-rebuilding process. Osteoporosis has also been associated with medications used to combat or prevent: Seizures, Gastric reflux, Cancer, Transplant rejection

Medical conditions – The risk of osteoporosis is higher in people who have certain medical problems, including: Celiac disease, Inflammatory bowel disease, Kidney or liver disease, Cancer, Lupus, Multiple myeloma, Rheumatoid arthritis

Lifestyle choices

• Sedentary lifestyle. People who spend a lot of time sitting have a higher risk of osteoporosis than do those who are more active
• Excessive alcohol consumption. Regular consumption of more than two alcoholic drinks a day increases your risk of osteoporosis.
• Tobacco use. Tobacco use contributes to weak bones.

PATHOGENESIS

The underlying mechanism in all cases of osteoporosis is an imbalance between bone resorption and bone formation. The three main mechanisms by which osteoporosis develops are an inadequate peak bone mass (the skeleton develops insufficient mass and strength during growth), excessive bone resorption, and inadequate formation of new bone during remodeling, likely due to mesenchymal stem cells biasing away from the osteoblast and toward the marrow adipocyte lineage.

DIAGNOSIS

Dual-energy x-ray absorptiometry (DEXA) is currently the criterion standard for the evaluation of BMD. It provides the patient’s T-score, which is the BMD value compared with that of control subjects who are at their peak BMD. World Health Organization (WHO) criteria define a normal T-score value as within 1 standard deviation (SD) of the mean BMD value in a healthy young adult. Values lying farther from the mean are stratified as follows

• T-score of –1 to –2.5 SD indicates osteopenia
• T-score of less than –2.5 SD indicates osteoporosis
• T-score of less than –2.5 SD with fragility fracture(s) indicates severe osteoporosis

TREATMENT

Women whose bone density test shows T-scores of -2.5 or lower, such as -3.3 or -3.8, should begin therapy to reduce their risk of fracture. Many women need treatment if they have osteopenia, which is bone weakness that is not as severe as osteoporosis.

The goals for treating osteoporosis are to slow or stop bone loss by:

• Proper nutrition- Foods and liquids that include calcium, vitamin D, and protein.

• Lifestyle changes- Avoid secondhand smoke, and if you smoke, quit, and drink alcohol in moderation

• Exercise. Combine strength training exercises with weight-bearing and balance exercises. Strength training helps strengthen muscles and bones in your arms and upper spine. Weight-bearing exercises — such as walking, jogging, running, stair climbing, skipping rope, skiing and impact-producing sports — affect mainly the bones in your legs, hips and lower spine. Balance exercises such as
• Fall prevention to help prevent fractures.

Medications-

• Bisphosphonates. Several bisphosphonates are approved to help preserve bone density and strength and to treat osteoporosis. This type of drug works by slowing down bone loss, which can lower the chance of fractures.
• Aledronate: Fosamax, Binosto
• Ibandronate: Boniva
• Risedronate: Actonel, Atelvia
• Zoledronic acid: Reclast

• Biologics– Denosumab (Prolia) is product that is available as an injection given every six months to women and men. It is often used when other treatments have failed. Denosumab can be used even in some cases of reduced kidney function. Its long-term effects are not yet known, but there are potentially serious side effects. These include possible problems with bones in the thigh or jaw and serious infection.

• Calcitonin. This medication is made from a hormone from the thyroid gland .
• Estrogen agonist/antagonist. An estrogen agonist/antagonist, also known as a selective estrogen receptor modulator (SERM), and tissue-selective estrogen complex (TSEC), are both approved to treat and prevent osteoporosis in postmenopausal women. They are not estrogen, but they have estrogen-like effects on some tissues and estrogen-blocking effects on other tissues. This action helps improve bone density, lowering the risk for some fractures.  selective estrogen receptor modulator raloxifene (Evista)
• Estrogen and hormone therapy. Estrogen and combined estrogen and progestin (hormone therapy) are approved to prevent osteoporosis and fractures in postmenopausal women.
• Parathyroid hormone (PTH) analog and parathyroid hormone related-protein (PTHrP) analog. PTH is a form of human parathyroid hormone that increases bone mass and is approved for postmenopausal women and men with osteoporosis who are at high risk for fracture. It is an injection and is usually prescribed for postmenopausal women who have a history of fractures.
• RANK ligand (RANKL) inhibitor. This is an inhibitor that helps slow down bone loss and is approved to treat osteoporosis in:Postmenopausal women or men with osteoporosis who are at high risk for fracture,Men who have bone loss and are being treated for prostate cancer with medications that cause bone loss,Women who have bone loss and are being treated for breast cancer with medications that cause bone loss,Men and women who do not respond to other types of osteoporosis treatment.

Sclerostin inhibitor. This is a medication that treats osteoporosis by blocking the effect of a protein, and helps the body increase new bone formation as well as slows down bone loss.

COMPLICATIONS

Bone fractures, particularly in the spine or hip, are the most serious complications of osteoporosis.

CONCLUSION

Many patients are unaware of the serious consequences of osteoporosis, including increased morbidity and mortality, and only become concerned when osteoporosis manifests in the form of fracture; accordingly, it is important to educate them regarding these consequences. Early prevention and treatment are essential in the appropriate management of osteoporosis.