Osteoporosis is a pathology in which the bones lose calcium, as a result of which they become brittle. In the presence of the slightest traumatic factor, they can deform or break. It is erroneously believed that this disease develops in people whose body receives an insufficient amount of calcium. It is not true. Osteoporosis develops even with an excess of this trace element in food. The cause of increased bone fragility is insufficient absorption of calcium by the bones or its "washout".
Etiology of osteoporosis
Bone density depends on the amount of sex hormones. Men have more testosterone than women, so their bones are much thicker and stronger. As a result, osteoporosis is more often diagnosed in the fair sex, especially in menopause, since at this time the level of hormones is significantly reduced.
Other causes of osteoporosis include physical inactivity, lack of vitamin D, drinking wine, smoking, chronic diseases (diabetes mellitus, thyroid lesions, chronic liver and kidney pathologies).
How to detectosteoporosis?
If a person notes increased fatigue and bone pain, changes in posture and gait, hair loss and deterioration of teeth, as well as frequent fractures, it is recommended to do densitometry. This is a quick and completely painless examination that allows you to determine and measure the loss of bone density, as well as establish the content of minerals and assess the risk of fractures. This examination is the most sensitive method for early diagnosis of osteoporosis.
The essence of densitometry is the transillumination of bone tissue with invisible x-rays. In this case, a low dose of ionized radiation is used, supplied in the form of two energy streams, which allows for a quick and accurate examination.
It should be noted that bone densitometry is characterized by a radiation dose that is kept to a minimum (it is less than 1/10 of the dose that patients receive during a standard chest x-ray).
When densitometry is done
Indications for this examination are the following conditions:
- early menopause or menopause, which occurs in women after the cessation of menstruation;
- presence of kidney failure;
- chronic liver disease;
- long-term treatment with glucocorticoids;
- nutrient malabsorption syndrome resulting in calcium deficiency;
- bone densitometry is also performed in the presence ofrheumatoid arthritis, hyperparathyroidism and hyperadrenocorticism, as well as hypothyroidism and diabetes mellitus.
If fractures are observed with minor injuries, this is also an indication for this examination. It is believed that the violation of the integrity of the bones in osteoporosis reduces the life expectancy of patients even more than cancer, so timely detection of the disease is extremely important. It should be noted that in some cases hereditary forms of this pathology are found.
Bone densitometry: main types
There are various methods for detecting osteoporosis, but their use is rather limited. Thus, various modifications of MRI are expensive, quantitative computed tomography gives a high dose of radiation, studies of the relevant biochemical parameters of bone metabolism are characterized by significant variations in normative data, and the patient feels discomfort during bone biopsy. When diagnosing osteoporosis, densitometry is the most popular method.
There are three main techniques that have been developed specifically to detect this disease:
- x-ray absorptiometry;
- ultrasound densitometry;
- peripheral computed tomography (has a significant drawback - it does not allow assessing the condition of the bones of the axial skeleton).
For the correct choice of research method and the correct assessment of the results obtained, take into accountfeatures of clinical manifestations. Appropriate diagnostic criteria are also taken into account.
Principles for evaluating densitometry results
The term “osteopenia” or “osteoporosis” is used to describe the data obtained after the examination. They should not be considered as a clinical diagnosis, but only as a symptom that can accompany any skeletal lesion with a decrease in its density. It should be noted that bone densitometry is not performed for a clear diagnosis, but to identify the risk of fractures in patients.
At the same time, the software of the equipment (densitometer) compares the results obtained and the selected database, and reflects the difference statistically. The number of standard deviations is determined, which is called the T-test (used to compare with young people of the same sex as the patient) or Z-test (a group of people of the corresponding age, sex or weight is taken for comparison).
If the T-criterion is no more than 2.5 SD, then this corresponds to osteopenia, if the results are below this indicator, then they speak of osteoporosis. These values are considered "threshold". This should be taken into account for the correct interpretation of densitometry results.
X-ray densitometry
Technically, most bones can be examined with x-rays. As a rule, densitometry of the spine (its lumbosacral region), as well as the hip joint, where fractures most often develop against the background of osteoporosis, is performed. They also determine the density of the bone tissue of the thigh and forearm or conduct densitometry of the whole body. This examination allows you to determine the content of minerals in certain areas of the body or throughout the body.
In the past, isotopic absorptiometry was used to estimate bone mass and mineral content, the principle of which is the exposure to gamma particles and the assessment of their degree of absorption. An important disadvantage of such an examination was a significant radiation exposure. Subsequently, two-photon x-ray absorptiometry was used, which was highly sensitive and less harmful to patients. To date, it detects only 2-3% of bone loss, so this examination can be used to screen postmenopausal women for early detection of osteoporosis.
Ultrasonic densitometry
This type of examination is done to assess bone strength. Density, microstructure and elasticity are taken into account, as well as the thickness of the cortical layer. An important advantage of such an examination is the absence of radiation exposure. Given the safety of this procedure, it can be repeated without any restrictions.
It must be said that such densitometry is based on the property of ultrasonic waves to propagate along the surface of the bone or dissipate in the bone tissue. At the same time, it is possible to determine the elasticity, density and stiffness of the bone.
NeedIt should be noted that ultrasonic bone densitometry is only used to examine the peripheral skeleton. Most often, this method examines the calcaneus and tibia, patella or phalanges of the fingers. Most devices measure the speed of ultrasound or its attenuation, which indicates not only bone density, but also the presence of trabeculae or microdamages.
Conclusion
Whether osteoporosis is viewed as a symptom or a disease, densitometry measures the risk of fracture. It should be remembered that the choice of the site of examination is extremely important, since the density or mineralization of bones cannot be the same for the entire skeleton.
To make the right choice, you need to know the following patterns:
- trabecular substance is affected by menopause, hypogonadal syndrome or steroid imbalance;
- primary damage to the cortical layer of bones is observed in senile, hyperthyroid, diabetic osteoporosis;
- If a patient in childhood or adolescence develops a disease in which the growth of the skeleton is disturbed, then systemic bone defects are diagnosed. They are accompanied by damage to both bone layers.
You need to know that there is a tendency for osteoporosis to “spread” from the axial skeleton to its peripheral areas, so for early diagnosis, the vertebrae should be examined first. Free densitometry, unfortunately,rare as this examination is usually performed in private clinics and requires appropriate equipment.
