What Causes Bone Loss?

Osteoporosis, or osteoporosis, is a group of bone diseases caused by a variety of causes. Bone tissue has normal calcification, calcium salts are in a normal ratio to the matrix, and metabolic bone disease is characterized by a decrease in bone tissue volume per unit volume. . Osteoporosis can occur in different genders and at any age, but is more common in postmenopausal women and older men. It is characterized by bone pain and easy fracture.

Basic Information

nickname: Osteoporosis
English name: osteoporosis
Visiting department: Endocrinology

Multiple groups: Middle-aged and elderly
Common causes: Osteoporosis easily caused by many diseases or after menopause
Common symptoms: Back pain, shortened length, hump, easy fracture, etc.
Contagious: no

Causes of osteoporosis

1. Idiopathic (primary)

Juvenile adult, menopause, senile.

Secondary

Endocrine cortisol, hyperthyroidism, primary hyperparathyroidism, acromegaly, hypogonadism, diabetes, etc. pregnancy, lactation. lack of nutritional protein, vitamin C, D deficiency, low calcium diet, alcoholism and so on. chromosomal abnormalities of hereditary osteogenesis imperfecta. liver disease. Nephropathy chronic nephritis hemodialysis. drugs corticosteroids, antiepileptic drugs, antitumor drugs (such as methotrexate), heparin and so on. Decadent systemic osteoporosis is seen in long-term bed rest, paraplegia, space flight, etc .; it is found locally after fracture, Sudecks atrophy, and bone atrophy after injury. gastrointestinal malabsorption gastrectomy. Rheumatoid arthritis. tumor multiple myeloma metastatic carcinoma, monocyte leukemia, Mast-Cell disease, etc. Other causes of osteopenia, transient or migrating osteoporosis.

Clinical manifestations of osteoporosis

Pain

The most common symptoms of primary osteoporosis are low back pain, which accounts for 70% to 80% of patients with pain. Pain spreads to both sides along the spine. Pain is relieved when supine or seated. It is stretched backward or prolonged when standing up, pain is aggravated when sitting for a long time. Bone pain usually occurs when more than 12% of bone mass is lost. In senile osteoporosis, the vertebral body is compressed and deformed, the spine is bent forward, muscle fatigue and even spasm, causing pain. Recent compression fractures of the thoracolumbar vertebrae can also cause acute pain, and the spinous processes of the corresponding parts may have intense tenderness and throbbing pain. If the corresponding spinal nerve is compressed, it can produce radiation pain in the extremities, sensory dyskinesia of both lower limbs, intercostal neuralgia, and sternal pain similar to angina. If compression of the spinal cord and cauda equina affects bladder and rectal function

2. Shortened length, hump

Most often appear after pain. The front part of the spine has a large load, especially the 11th, 12th thoracic vertebrae and the 3rd lumbar vertebrae. The load is greater, and it is easy to compress and deform, causing the spine to lean forward and form a hump. Enlargement, vertebral body compression during osteoporosis in the elderly, each vertebral body shortened by about 2 mm, the average length shortened by 3 to 6 cm.

3. Fracture

It is the most common and serious complication of degenerative osteoporosis.

4. Reduced respiratory function

Compression fractures of the thorax and lumbar spine, kyphosis, and thoracic deformities can significantly reduce vital capacity and maximum ventilation. Patients often experience symptoms such as chest tightness, shortness of breath, and difficulty breathing.

Osteoporosis

Laboratory inspection

(1) Serum calcium, phosphorus , and alkaline phosphatase In primary osteoporosis, serum calcium, phosphorus, and alkaline phosphatase levels are usually normal, and alkaline phosphatase levels can increase in the months following a fracture.

(2) Blood parathyroid hormone should be checked for parathyroid function except for secondary osteoporosis. Patients with primary osteoporosis may have normal or elevated blood parathyroid hormone levels.

(3) Some markers of bone renewal in osteoporosis patients can reflect the status of bone turnover (including bone formation and bone resorption). These biochemical measurement indicators include: bone specific alkaline phosphatase (responding to bone formation) , Tartrate-resistant acid phosphatase (reactive bone resorption), osteocalcin (reactive bone formation), type I procollagen peptide (reactive bone formation), uridine and deoxypyridoline (reactive bone resorption), NC of type I collagen -Terminal cross-linked peptide (reactive bone resorption).

(4) The normal ratio of morning urine calcium / creatinine ratio is 0.13 ± 0.01. Too much urine calcium will increase the ratio, suggesting that the bone resorption rate may increase.

2. Auxiliary inspection

(1) Bone imaging examination and bone density Take X-rays of the lesions to find fractures and other lesions, such as osteoarthritis, intervertebral disc disease, and spine forward. Decreased bone mass (low bone density) can be seen when the osteopenia is increased, the trabecular bone is reduced and the gap is widened, the transverse trabecular bone disappears, and the bone structure is blurred, but it is usually observed when the bone mass is reduced by more than 30% . Generally, the vertebral body is double-concave deformed, and the anterior edge of the vertebral body collapses into a wedge shape, also known as a compression fracture, which is common in the 11th and 12th thoracic vertebrae and the 1st and 2th lumbar vertebrae. Bone density test Bone density test is a predictive indicator of fracture. The measurement of bone density at any site can be used to assess the overall risk of fracture; measurement of bone density at a specific site can predict the risk of local fracture.

According to the latest United States National Osteoporosis Foundation's treatment guidelines, bone density testing is required in the following populations: postmenopausal women over 65 years of age, despite various precautions, osteoporosis in this population The risk of osteoporosis should be treated accordingly; postmenopausal women with one or more risk factors and less than 65 years of age; postmenopausal women with fragile fractures; Women who decide to treat; women who have long-term hormone replacement therapy; men who have fractures after minor trauma; people who have X-rays showing osteopenia, and patients with other conditions that can cause osteoporosis.

The WHO recommends grading osteoporosis according to BMD values, stipulating that normal and healthy adults' BMD value plus or minus 1 standard deviation (SD) is a normal value, which is lower than the normal value (1 to 2.5). Osteoporosis above 2.5SD; severe osteoporosis with a reduction above 2.5SD accompanied by fragile fractures.

Osteoporosis diagnosis

The diagnosis of postmenopausal and senile osteoporosis must first exclude secondary osteoporosis caused by various other causes, such as hyperparathyroidism and multiple myeloma, osteomalacia, and renal bone Malnutrition, osteogenesis imperfecta in children, metastases, leukemia, and lymphoma.

In 1994, WHO recommended grading diagnosis of osteoporosis based on BMD or BMC (bone mineral content) value: Normally BMD or BMC is within 1 standard deviation (SD) of the average bone density of normal adults; bone loss is BMD or BMC is 1 to 2.5 standard deviations lower than the average bone density of normal adults; osteoporosis is BMD or BMC is more than 2.5 standard deviations lower than the average bone density of normal adults; severe osteoporosis is more than The mean bone mineral density of normal adults was reduced by more than 2.5 standard deviations with one or more fragile fractures. The diagnostic criteria for BMD or BMC can be measured on the axial or peripheral bones.

Differential diagnosis of osteoporosis

Osteomalacia

Clinically, there is a history of gastrointestinal malabsorption, fatty rash, partial gastrectomy, or a history of kidney disease. Early bone X-rays are often difficult to distinguish from osteoporosis. However, if there is a false fracture line (Looser band) or bone deformation, it is mostly osteomalacia. Biochemical changes are more obvious than osteoporosis.

(1) Osteomalacia caused by vitamin D deficiency often has low blood calcium and blood phosphorus, increased blood alkaline phosphatase, and decreased calcium and phosphorus in urine.

(2) Renal bone lesions are more common in renal tubular lesions. If glomerular lesions are present at the same time, blood phosphorus may be normal or high. Due to hypocalcemia and hyperphosphatemia, patients have secondary hyperparathyroidism.

Myeloma

The bone X-rays of typical patients are often decalcified with clear edges, which must be distinguished from osteoporosis. The patients' blood alkaline phosphatase was normal, the blood calcium and phosphorus varied, but the plasma globulin (immunoglobulin M) was often increased and the present week protein appeared in the urine.

3. Hereditary osteogenesis imperfecta

Possibly due to less bone matrix produced by osteoblasts, the result is osteoporosis. Calcium, phosphorus, and alkaline phosphatase in the blood and urine are normal, and patients often have other congenital defects, such as deafness.

4. Metastatic cancerous bone disease

Clinical manifestations of primary cancer, blood and urine calcium often increase, with urinary calculi. X-ray showed bone invasion.

Osteoporosis complications

The most common complication: osteoporosis fractures occur in indoor daily activities such as twisting the body, holding objects, and opening windows. Fractures can occur even without a significant external force. Fractures occurred at the thorax, lumbar vertebra, distal radius and upper femur.

Osteoporosis treatment

The effective measures are as follows.

Sports

In adulthood, multiple types of exercise help maintain bone mass. Menopausal women insist on exercise for 3 hours per week, and overall calcium increases. However, amenorrhea caused by excessive exercise, bone loss has accelerated. Exercise also improves sensitivity and balance.

2. Nutrition

Good nutrition is important to prevent osteoporosis, including sufficient amounts of calcium, vitamin D, vitamin C, and protein. From childhood, the daily diet should have sufficient calcium intake, and calcium affects the acquisition of peak bones. European and American scholars advocate that the calcium intake for adults is 800-1, 000mg, postmenopausal women are 1,000-1,500mg per day, men 65 years old and other patients with osteoporosis risk factors, recommended calcium intake It is 1500 mg / day. Vitamin D intake is 400-800U / day.

3. Prevent Wrestling

Patients with osteoporosis should be minimized to reduce hip fractures and Colles fractures.

4. Drug treatment

Effective medications can prevent and treat osteoporosis, including estrogen replacement therapy, calcitonin, selective estrogen receptor modulators, and diphosphates. These drugs can prevent bone resorption but have only a small effect on bone formation . The drugs used to treat and prevent the development of osteoporosis are divided into two major categories. The first category is drugs that inhibit bone resorption, including calcium, vitamin D and active vitamin D, calcitonin, diphosphate, estrogen, and isoprene. Flavonoids; the second category is to promote bone drug, including fluoride, anabolic steroids, parathyroid hormone and isoflavones.

(1) Hormone replacement therapy Hormone replacement therapy is considered to be the best choice for the treatment of osteoporosis in postmenopausal women. It is also the most effective treatment method. The problem is that hormone replacement therapy may bring adverse reactions in other systems. Hormone replacement therapy is avoided for patients with breast disease and for those who cannot tolerate its side effects. Estradiol is recommended to be taken immediately after menopause, and for life if tolerated. Take it periodically, that is, use it continuously for 3 weeks and stop using it for 1 week. Allergies, breast cancer, thrombophlebitis, and undiagnosed vaginal bleeding are contraindicated. In addition, ethinyl estradiol and norethisterone are progestins used to treat moderate to severe vasomotor symptoms related to menopause. Androgen research shows that for male patients with osteoporosis caused by severe lack of sex hormones, giving testosterone replacement therapy can increase BMD of the spine, but it seems to be ineffective for the hip bone, so androgens can be regarded as an anti-bone resorption drug. Intramuscular injection of testosterone , once every 2 to 4 weeks, can be used to treat patients with decreased BMD with hypogonadism. Impaired renal function and cautious use of testosterone in elderly patients, so as not to increase the risk of prostate hyperplasia; testosterone can increase the growth of subclinical prostate cancer, so the drug needs to be monitored for prostate specific antigen (PSA); liver function, blood routine and cholesterol need to be monitored ; If there is edema and jaundice, the drug should be discontinued. The supply of calcium and vitamin D should be ensured during the medication. Another topical testosterone is available.

(2) Selective estrogen receptor modulators This class of drugs has a weak estrogen-like effect in some organs, while it can play an estrogen antagonistic role in other organs. SERMs prevent osteoporosis and reduce the incidence of cardiovascular disease, breast cancer, and endometrial cancer. These drugs include raloxifene, a nonsteroidal phenanthrene thiophene, an estrogen agonist, which can inhibit bone resorption, increase BMD in the spine and hips, and reduce the risk of vertebral fractures by 40% to 50%. , But the efficacy is worse than estrogen. Premenopausal women are disabled.

(3) Diphosphates Diphosphates are synthetic analogs of pyrophosphate combined with hydroxyapatite in bones, which can specifically inhibit osteoclast-mediated bone resorption and increase bone density. The specific mechanism It is still not completely clear, and considerations have to do with regulating the function and activity of osteoclasts. Prohibited in pregnant women and women planning to become pregnant. The first generation was named sodium hydroxyethylphosphonate, called etidronate. The therapeutic dose had adverse reactions that inhibited bone mineralization. Therefore, intermittent and periodic dosing was recommended, and hydroxyethylphosphonic acid was continuously taken at the beginning of each cycle. Sodium for 2 weeks, discontinuation for 10 weeks, every 12 weeks as a cycle. Calcium should be taken with sodium hydroxyethylphosphonate.

In recent years, there has been a new generation of phosphates used in clinical applications, such as amino diphosphates, risedronic acid, chloroarsinic acid (chloroformic acid dichloride), and pamidronate. Bone mineralization was not affected at the therapeutic dose. Alendronate has been shown to reduce bone resorption, reduce the incidence of spine, hip, and wrist fractures by up to 50%, and use it before menopause can prevent glucocorticoid-related osteoporosis.

(4) Calcitonin Calcitonin is a peptide hormone that can rapidly inhibit the activity of osteoclasts, and slow action can reduce the number of osteoclasts. It has the function of analgesia, increased activity and improved calcium balance. Patients have analgesic effect, suitable for patients with contraindications or intolerance of diphosphate and estrogen. The commonly used preparations in China are calcitonin and ecalcitonin. Calcitonin can be administered parenterally and intranasally. The effect of parenteral administration can last up to 20 months.

(5) Vitamin D and calcium Vitamin D and its metabolites can promote the absorption of calcium in the small intestine and mineralize bone. Active vitamin D can promote bone formation, increase osteocalcin production, and alkaline phosphatase activity. Taking active vitamin D can reduce the incidence of vertebral and extravertebral fractures in patients with osteoporosis than taking calcium alone. Another combination preparation of vitamin D and calcium is available, and the treatment effect is more reliable.

(6) Fluoride Fluoride is an effective stimulator of bone formation, which can increase bone density of the vertebral body and hip and reduce the incidence of vertebral body fractures. A small daily dose of fluorine can effectively stimulate bone formation with little side effects.

For patients with osteopenia and osteoporosis treated, it is recommended to review BMD every 1 to 2 years. If the bone renewal index is high, the drug should be reduced. To prevent long-term bone loss, it is recommended that women start estrogen replacement therapy after menopause for at least 5 years, preferably 10-15 years. If the patient is diagnosed with a disease known to cause osteoporosis, or if a drug that specifically causes osteoporosis is used, it is recommended that calcium, vitamin D and diphosphate be given at the same time.

5. Surgical treatment is only required after a fracture due to osteoporosis.

Osteoporosis prognosis

The main factors affecting the prognosis are related complications after fracture. Although osteoporosis cannot be completely prevented, given certain preventive measures, such as adequate intake of calcium, vitamin D, exercise, etc., can greatly reduce osteoporosis. To prevent serious complications.

Osteoporosis prevention

Osteoporosis brings great inconvenience and pain to patients' lives, the treatment results are very slow, and once fractures can be life-threatening, special emphasis must be placed on the implementation of tertiary prevention:

Primary prevention

It should start with children and adolescents. For example, pay attention to reasonable diet and nutrition, and eat more foods containing calcium and phosphorus, such as fish, shrimp, milk, dairy products, bone soup, eggs, beans, miscellaneous grains, green leafy vegetables and so on. Adhere to a scientific lifestyle, such as insisting on physical exercise, more sunbathing, no smoking, no drinking, less coffee, strong tea and carbonated drinks, less sugar and salt, animal protein should not be too much, late marriage, less education, The breastfeeding period should not be too long. Preserving calcium in the body as much as possible, enriching the calcium pool, and increasing the peak bone value to the maximum are the best measures to prevent osteoporosis in later life. For those at high risk with genetic genes, focus on follow-up and early prevention and treatment.

2. Secondary prevention

In middle age, especially after menopause, bone loss is accelerated. During this period, bone density examination should be performed once a year, and prevention and treatment measures should be taken as soon as possible for those with rapid bone loss. In recent years, most scholars in Europe and the United States have advocated that long-term estrogen replacement therapy should be started within 3 years after menopause. At the same time, adhere to long-term preventive calcium supplementation to prevent osteoporosis safely and effectively.

3. Tertiary prevention

Patients with degenerative osteoporosis should be actively treated with drugs that inhibit bone resorption and promote bone formation (active VitD), and should also strengthen measures such as anti-fall and anti-tampering. Middle-aged and elderly patients with fractures should be actively operated with strong internal fixation and early activities. Comprehensive treatments such as physical therapy, physical therapy psychology, nutrition, calcium supplementation, curb bone loss, and improve immune function and overall quality.