Osteoporosis results from a loss of bone mass (measured as bone density) and from a change in bone structure. Many factors will raise your risk of developing osteoporosis and breaking a bone. You can change some of these risk factors, but not others. Recognizing your risk factors is important so you can take steps to prevent this condition or treat it before it becomes worse. Major risk factors that you cannot change include:

• Older age (starting in the mid-30s but more likely with advancing age) White race / white or pale skin

• Small bone structure

• Family history of osteoporosis or an osteoporosis-related fracture in a parent or sibling

• Prior fracture due to a low-level injury, particularly after age 50 

Risk factors that you may be able to change include:

• Low levels of sex hormone, mainly estrogen in women (e.g., menopause)

• Cigarette smoking

• Alcohol abuse

• Low calcium and vitamin D, from low intake in your diet or inadequate absorption in your gut

• Sedentary (inactive) lifestyle or immobility

Our bones are always changing — not just during the growth phases of childhood and adolescence, but throughout our lives. New bone is constantly forming to replace old bone that has been broken down in a process called resorption. This constant bone resorption and formation is part of a normal, daily process known as bone remodeling.It is a state of continual bone turnover that allows fully developed bones to maintain and renew themselves. If there is more bone formation than resorption, our bones become stronger. If the two processes occur at equal rates, our bones are stable. If resorption is greater than formation, our bones weaken.

In our lifetime upto the age of 30, new bone formation is higher than resorption and results in maximum bone density at the age of 30 and gradually after age of 30 bones lose strength. In case of females in first few years after menopause, bone loss is rapid and continues throughout life.

In osteoporosis; bone resorption rate is higher than new bone formation and gradually our bones become weak bones become so weak, which makes bone more brittle, fragile, and likely to break after minor trauma. According to the strength of bone, different stages of osteoporosis are classified:

Stages of Osteoporosis

• Bone pain due to weak bones
• Fractures due to low impacts
• Compression fractures in vertebral column
• Stooped posture
• Loss of height

	Fractures of the hip, wrist, arm and rib are common in people with osteoporosis

Bone mineral density (BMD):
Bone mineral density is the amount of mineral matter (calcium and other types of minerals) per square centimeter of bone. It is used in clinical medicine as an indirect indicator of osteoporosis and fracture risk.

Bisphosphonates:
A class of drugs that are used in the treatment of osteoporosis by preventing the loss of bone mass.  Example: alendronate, risedronate, zoledronic acid etc.

Bone resorption:
It is the process by which osteoclasts break down bone and release the minerals, resulting in a transfer of calcium from bone to the blood.

Bone remodeling:
Bone remodeling is a continuous life-long process where mature bone tissue is removed from the skeleton and new bone tissue is formed. Bone remodeling also controls the replacement of bone following injuries like fractures and micro-damage, which occurs during normal activity.

Calcitonin:
Calcitonin is a hormone secreted by the parafollicular or C cells of thyroid gland. It plays a major role in calcium and phosphorus metabolism. Calcitonin suppresses bone resorption by inhibiting the activity of osteoclasts.

Calcium:
Calcium is an essential mineral which is important for formation and maintenance of healthy bones. Recommended daily intake of calcium for adults is around 1200 mg.

Compression fracture:
Compression fracture is a collapse of a vertebra. It is the most common type of fracture affecting the spine and it generally results from osteoporosis.

DEXA/DXA:
Dual-energy X-ray absorptiometry is used to measure bone mineral density for diagnosis and follow-up of osteoporosis. As per WHO guidelines, T-score of less than -2.5 (measured by DEXA) indicates osteoporosis.

Estrogens:
Estrogens are a group of sex hormones in women and responsible for the development of secondary sex characteristics during woman’s reproductive process. Estrogen levels are reduced after menopause. This can cause a decrease in bone density, leading to osteoporosis.

Bone fracture:
Bone fracture is a condition in which a break in the continuity of the bone occurs. Bone fracture may result from injury or a disease process.

Fragility fracture:
Fracture caused by a fall from a standing height or lower, or in the absence of any obvious trauma, is called fragility fracture. It results from mechanical forces that would not ordinarily cause fracture in a healthy, young adult.

Hip fracture:
Hip fracture is a break in the upper quarter of the femur (thigh) bone. In majority of cases, a hip fracture is a fragility fracture due to a fall or minor trauma in people with weakened osteoporotic bone.

Hyperparathyroidism:
Excessive production of parathyroid hormone (PTH) is called hyperparathyroidism.

Osteopenia:
Osteopenia is a condition in which the bone mineral density is lower than normal but yet not low enough to be classified as osteoporosis. As per WHO guidelines, T-score between -1.0 and -2.5 is considered as osteopenia.

Osteoporosis:
Osteoporosis is a condition in which bones become porous and weak. It is because there is an imbalance between bone formation and bone breakdown by a process known as bone resorption. As a result, bones can break more easily. As per WHO guidelines, T-score less than -2.5 (measured by Dual X-ray absorptiometry, [DXA]) indicates osteoporosis, whereas T-score greater than -1 is normal.

Postmenopausal:
Postmenopausal stage is the period following menopause, which generally starts 12 months after cessation of menstruation.

PTH:
Parathyroid hormone is secreted by parathyroid gland as a polypeptide containing 84 amino acids. That is why it is called as PTH. PTH enhances release of calcium from the bones, thereby increasing the plasma concentration of calcium.

rH-PTH (1-34):
Recombinant human parathyroid hormone (teriparatide) is the synthetic version of PTH. Teriparatide has identical 1-34 N-terminal amino acids of human PTH, which is responsible for its biological activity. It is produced by employing recombinant DNA technology.

T-Score:
T-score is the relevant measure for screening of osteoporosis. It is a comparison of a patient's BMD at a particular site with that of a healthy thirty-year-old of the same gender and ethnicity.

Vitamin D:
Vitamin D is a fat-soluble vitamin, which enhances the absorption and metabolism of calcium and phosphorous. People exposed to normal quantities of sunlight do not need vitamin D supplements because sunlight promotes formation of sufficient vitamin D in the skin.