Osteoporosis, or porous bone, is a disease that affects bone density and quality, leading to an increased risk of fractures due to bone fragility. Osteoporosis affects both men and women, but white and Asian women are at the highest risk. There are two subtypes of osteoporosis, primary and secondary. 

An imbalance between new bone formation and old bone resorption causes osteoporosis. There are many risk factors that increase the chance of having osteoporosis, such as gender, age, race, family history, body frame size, hormones levels, medications, and dietary factors. 

Formation and resorption of bones are regulated by parathyroid hormone, calcitonin, estrogen, vitamin D, various cytokines, and other local factors such as prostaglandins. 

Usually, there are no symptoms in the early stages of osteoporosis.  Some of the signs and symptoms that may appear include back pain, loss of height over time, stooped posture, and bone fractures that occur much more easily than expected. 

The most common method to detect bone loss and spine and hip bone density is a dual-energy X-ray absorptiometry scan, often abbreviated DXA. Other methods to detect osteoporosis include radiological assessments, bone turnover markers  , and blood markers .

Many medications are available to treat osteoporosis, like bisphosphonates, estrogen and estrogen receptor modulators, teriparatide, calcitonin, and denusomab. 

Hip and spine fractures from minor falls or accidents can lead to back pain, disability, and even death.  The best ways to prevent osteoporosis is by regular exercise, healthy eating and taking vitamin D supplements ، Limiting alcohol intake and quitting smoke also help reduce the risk of osteoporosis.

The World Health Organization Collaborating Center for Public Health Aspects of Rheumatic Diseases and the University of Liège, Belgium, conducted a study that found that over 200 million people in the world suffer from osteoporosis.

Osteoporosis is a chronic, progressive disease which causes the bones to become more fragile and break easily due to an imbalance in bone formation and resorption. Fractures of the hip, spine, and wrist are the most common among people with osteoporosis. 

Osteoporosis is classified into to two subtypes:

• Primary Osteoporosis

Primary osteoporosis is mainly due to age-related bone loss, or bone loss due to unknown causes. There are two types of primary osteoporosis:

• • Juvenile osteoporosis occurs in children or young adults of both sexes between 8 and 14 years old. This type is characterized by sudden bone pain and/or fracture. 

• • Idiopathic osteoporosis, which is further subdivided into:
• Postmenopausal osteoporosis (type I), which occurs in women with estrogen deficiency. Type 1 osteoporosis leads to accelerated bone loss primarily from trabecular bone, one of two bone tissues characterized by being spongy. Fractures of the distal forearm and the bodies of vertebra are common in this type.

• Age-associated or senile osteoporosis (type II), which occurs in women and men due to bone loss associated with aging. This type affects both bone tissues, the dense, compact cortical bone, and the spongy trabecular bone. The most common fractures are of the wrist, vertebrae, and hip. 

• Secondary osteoporosis

Secondary osteoporosis is caused by the presence of underlying conditions, such as hyperthyroidism, a side effect of certain medications, such as glucocorticoids used to treat inflammation. Secondary osteoporosis may also result from lifestyle habits, e.g. smoking and excessive drinking. 

Osteoporosis occurs when there is an imbalance between new bone formation and old bone resorption. Some people lose bone density much faster than normal due to many risk factors. 

Risk factors that increase that chance of developing osteoporosis include gender, hormone levels, dietary factors, medications used and other medical conditions:

Gender

Women are much more likely to develop osteoporosis than are men.

The hormone estrogen is essential for healthy bones and bone density in women. In the menopause period, hormone levels change and directly affect bone density. Other factors that cause an increased risk of osteoporosis in women are:

• Early menopause (before the age of 45).
• Undergoing a hysterectomy, or removal of the womb, before the age of 45.
• Absent periods for more than six months. 

In men, the cause of osteoporosis is unknown. However, the male hormone, testosterone, helps keep bones healthy. The risk of osteoporosis increases when levels of testosterone are low. The known causes of low levels of testosterone hormone include:

• Use of certain medications, such as oral corticosteroids.
• Alcohol misuse.
• Hypogonadism, which is a condition that causes abnormally low testosterone levels. 

Hormones level

Other hormones can contribute to the development of osteoporosis in addition to the sex hormones mentioned above. Increased levels of hormones produced by the thyroid gland and parathyroid gland, in addition to disorders of the pituitary and adrenal glands increase the chance of developing osteoporosis.  

Age

The risk of osteoporosis increases with age.

Race

White and Asian people are at the highest risk of osteoporosis.

Family history

People with a family member with osteoporosis are at an increased risk of developing it themselves.

Body frame size

Men and women who have small, thin body frames tend to have a higher chance  of having osteoporosis because they may have less bone mass to draw from as  they age. 

Dietary factors

Some dietary factors play a role in the development of osteoporosis. These factors include:

•          Low calcium intake

Calcium is an essential mineral for building strong and healthy bones. Low calcium in a person’s diet may lead to diminished bone density, early bone loss and an increased risk of osteoporosis. 

•          Eating disorders

Severely restricting food intake and being underweight weakens bone in both men and women. The most common eating disorders that increase the risk of osteoporosis are anorexia nervosa and bulimia.

•          Gastrointestinal surgery

Gastrointestinal surgery to remove part of the intestine or reduce the size of stomach reduces the surface available to absorbs nutrients, including calcium, which may lead to an increased risk of osteoporosis. 

•          low vitamin D levels.

Vitamin D promotes calcium absorption and is important for healthy bones. Low levels of vitamin D can increase the risk of developing osteoporosis. 

Steroids and other medications

Osteoporosis is linked with many medications that increase the risk of developing it, such as long-term use of corticosteroid medications (prednisone and cortisone), anti-epileptic drugs, breast cancer treatments, such as aromatase inhibitors, and prostate cancer drugs.

Other medicines may increase the risk of osteoporosis including drugs used to reduce inflammation of the stomach and esophagus, diabetes drugs, contraceptives, and some drugs used for treating mental health problems. 

Medical conditions

Some medical conditions are associated with an increased risk of osteoporosis, such as inflammatory bowel disease, kidney or liver disease, cancer, diabetes, HIV, dementia, Parkinson’s disease, and rheumatoid arthritis. 

Bones gradually start losing density around the age of 35. Some people lose bone density much faster than normal and develop osteoporosis due to many risk factors.

There are two types of bones, cortical and trabecular. Dense cortical bone and spongy trabecular bone differ in their architecture but are similar in molecular composition. Trabecular bone is more porous with a higher bone turnover. Loss of both types of bone contributes to skeletal fragility. 

The balance between bone resorption and bone formation is determined by the activities of two principle cell types, osteoclasts and osteoblasts, and the process is regulated by several substances in the body including parathyroid hormone, calcitonin, estrogen, vitamin D, various cytokines, and other local factors such as prostaglandins.  An imbalance between bone resorption and bone formation caused by any reason leads to a reduction in skeletal mass which causes osteoporosis.

Osteoporosis has no obvious symptoms in the early stages of bone loss. Later signs and symptoms of osteoporosis include:

• Back pain, caused by a fractured or collapsed vertebra.
• Loss of height over time.
• Stooped posture.
• Bone fractures that occurs more easily than expected. 

Osteoporosis causes no apparent symptoms in the early stages of bone loss, so it may be difficult to diagnose. Osteoporosis can be diagnosed through the following:

Bone mineral density test (BMD)

The best way to check for bone health is by a BMD test. The most common method is dual-energy X-ray absorptiometry scan, or DXA. DXA is a low radiation X-ray that detects bone loss and is used to measure spine and hip bone density. 

Other types of BMD tests include:

• Peripheral DXA, which is used to measure bone mass at the forearm, fingers and heel.

• Single-energy X-ray absorptiometry to measure bone density at the heel or wrist. 

• Dual photon absorptiometry to measure bone density at the spine, hip or total body.

• Single photon absorptiometry to measure bone density at the wrist.

• Quantitative Computed Tomography (QCT), which measures the spine or hip.

• Peripheral QCT, measuring bone density at the forearm.

• Quantitative Ultrasound, which uses sound waves to measure bone density at the heel or fingers. 

Blood and urine tests

Blood and urine tests may help detect medical conditions that may be causing osteoporosis. Finding the underlying cause is important for choosing the best treatment for the patient. 

Bone Turnover Markers (BTM)

Bone Turnover Markers (BTM) have been extensively used in clinical research to monitor the efficacy and mechanisms of action of new drugs in the treatment of osteoporosis. There are three categories of BTM, bone resorption markers, bone formation markers and markers of osteoclast regulatory proteins . However, these markers, which are measured in serum or urine, are not specific to osteoporosis, and they assess alterations in skeletal metabolism regardless of the cause. Combining BMD with BTM could improve fracture prediction in postmenopausal women. 

Treatment for osteoporosis may involve one or more of the following:

Lifestyle Changes

Certain lifestyle changes can effectively support bone health and strength. These include changing diet to include more calcium and developing an exercise routine.

Supplements and Medications

Taking calcium and vitamin D supplements help support bone health and strength. Medications that affect bone health may also be used in the treatment of osteoporosis. Medications include:

• Bisphosphonates

Bisphosphonates inhibit the breakdown of bone and increase bone density. Bisphosphonates are the main drugs used to prevent and treat osteoporosis in postmenopausal women.  

• Estrogen and estrogen receptor modulators

Medications that include estrogen is typically used for bone health in younger women or in women whose menopausal symptoms also require treatment. Estrogen therapy can increase the risk of blood clots, endometrial cancer, breast cancer and possibly heart disease.  

• Teriparatide

Teriparatide is an effective stimulator of bone formation. 

• Calcitonin

Calcitonin is used to reduce pain associated with acute vertebral fractures. 

• Denusomab

Denusomab minimizes bone loss, increases bone density, and reduces the chance of all types of fractures. It inhibits bone resorption strongly and rapidly. 

Surgery

Surgery for patients with osteoporosis is mainly performed to treat severe spinal fractures. Surgical procedures for this purpose include:

• Kyphoplasty: This surgery is used to treat spinal fractures and restore the height of the vertebrae by placing a material into a bone of the spine. 

• Spinal fusion: This is done by joining the bones of the spine together to prevent them from moving against each other. 

The most serious complication of osteoporosis is bone fractures, particularly in the spine or hip. These fractures result from minor falls or accidents. The result of hip fractures are disability and increased risk of death within the first year after the injury. Spine fractures or crumbling can result in back pain, loss of height and a hunched forward posture.  

There are many ways that may help reduce the risk of osteoporosis, such as:

Regular exercise

Regular exercise helps build strong bones and slows bone loss.  Adults between 19 to 64 years should do at least 150 minutes of exercise, such as cycling or fast walking, every week. (18)

Healthy eating

Good nutrition helps in keeping bones healthy.  The two most important nutrients for healthy bones are calcium and vitamin D.

• Calcium

Calcium is important for healthy bones; good sources of calcium include:

• Low-fat dairy products.
• Dark green leafy vegetables.
• Canned salmon or sardines with bones.
• Soy products, such as tofu.
• Calcium-fortified cereals and orange juice. 

• Vitamin D

Vitamin D promotes calcium absorption and is important for healthy bones. People can get adequate amounts of vitamin D from sunlight. Other sources include:

• Oily fish.
• Sardines.
• Red meat.
• Liver.
• Egg yolks.
• Fortified foods such as most fat spreads and some breakfast cereals.
• Dietary supplements. 

Lifestyle habits

Other healthy lifestyle habits that help in reducing the risk of osteoporosis include  exercise routine, and stopping smoking.

Osteoporosis is treatable and the risk of fractures can be reduced if detected early. The outcomes of osteoporosis depend on where fractures occur, if they do. Hip and spine fractures are a particularly dangerous result of osteoporosis, especially in the elderly, as they can cause chronic pain, disability, and even death. Hip fractures are one of the main reasons people are admitted to nursing homes. 

A study performed by the World Health Organization Collaborating Center for Public Health Aspects of Rheumatic Diseases and the University of Liège, Belgium,  reports that more than 200 million people worldwide suffer from osteoporosis. 

According to the World Health Organization, an estimated 1.3–1.7 million hip fractures occurred worldwide in 1990. By 2025, this number is expected to increase to almost 3 million.