Bone densitometry

Densitometry and Osteoporosis

Bone densitometry is a diagnostic technique that allows to evaluate the mineral density of the bones, making it particularly useful in the diagnosis and monitoring of osteoporosis.

This skeletal disease is characterized by the reduction of the mineral content of the bones and the deterioration of the microstructure that characterizes them; as such, it exposes patients to an important risk of suffering fractures even for minor trauma. In general, this risk is greater the less the bone mass is; for this reason densitometry is currently considered the gold-standard for the instrumental diagnosis of osteoporosis and an important "predictor" of fracture risk.

How does it work

Bone densitometry uses a very small dose of X-rays to establish how many grams of calcium and other minerals are present in the bone segment examined; the radiation doses are so low that even the frequent repetition of the examination does not represent any danger to the patient's health.

Among the different types of instruments available, DEXA is currently the most used.

Execution and Preparation

The time required for the investigation is about 10 minutes, it is in no way painful and there is no need for special dietary or pharmacological preparations. At the end of the procedure the patient can then resume normal occupations normally.

The only precaution is to postpone the densitometry for a few days in case of recent subjecting to a scintigraphic or radiological examination with a baryte contrast medium (the evaluation in this regard is the responsibility of the nuclear medicine specialist). metal parts such as coins, buckles, watches, bracelets and the like will be removed from the field of exploration.

Locations examined

The skeletal segments studied by bone densitometry vary in relation to the characteristics of the patient; in general, the lumbar spine is assessed in younger women (<65 years) and the femoral neck in older women and / or with spinal pathologies. Sometimes, the examination may be conducted on both segments or at the radius (forearm).

Bone densitometry allows to find out if a person is affected by osteoporosis and to establish its level of severity; it can also quantify the future risk of developing the disease and helps to evaluate the effectiveness of the therapies undertaken.

Indications

Who Should Undergo Bone Densitometry?

The densitometric investigation is particularly indicated in the presence of important risk factors for osteoporosis, which materialize in the following clinical conditions:

• aged women > 65 years and in menopause for at least a decade (some guidelines recommend bone densitometry even for men over 70 years old);
• premature menopause (< 45 years);
• surgical menopause (removal of the ovaries during the fertile period);
• various causes of estrogen deficiency (primary hypogonadism or secondary amenorrhea lasting more than a year);
• constitutional factors that predispose to osteoporosis (pre and postmenopausal women with body mass index <19 kg / m², long-limbed, sedentary with reduced muscle mass);
• significant dietary deficiencies (inadequate calcium and vitamin D intake);
• symptoms that suggest the presence of osteoporosis: decrease in stature more than 3 cm, curvature of the spine or fracture caused by a minor accident;
• recent or future subjected to prolonged treatments with high dose cortisone or other osteopenizing drugs (for example antiepileptics, methotrexate, immunosuppressive therapies after organ transplantation);
• previous fractures not due to major trauma;
• diseases that favor bone demineralization (hypercortisolism - Cushing's syndrome, hyperthyroidism, renal failure, hyperparathyroidism);
• strongly positive family history of osteoporosis;
• more than 20 cigarettes a day, alcohol abuse.

In the presence of one or more of these risk factors it is important to contact your doctor to evaluate the opportunity to undergo a bone densitometry or not.

Results

The diagnosis of osteoporosis is based on the comparison of the densitometric result with

• the average of healthy adult subjects of the same sex and aged 25-30 years (therefore examined when they reach the peak bone mass - T-score);
• and / or the average of subjects of the same age and sex (Z-score).

According to the WHO, the diagnosis of osteoporosis must be carried out, limited to the DEXA technique, considering the densitometric values, expressed in T-score according to the following scheme:

T-SCORE BONE HEALTH > -1 NORMAL <-1 and > -2.5 OSTEOPENIA < -2.5 OSTEOPOROSIS <-2.5 with fracture SEVERE OSTEOPOROSIS

NOTE: a T-score equal to 0 indicates that the subject examined has a bone density equal to the average of young people; a T-score equal to or greater than -1 is still considered normal. In the presence of a T-score between -1 and -2.5 the subject has a reduced bone density, not so severe as to speak of osteoporosis but still sufficient to induce him to set up, together with his doctor, an effective treatment to prevent a further bone demineralization. Finally, a T-score equal to or lower than -2.5 indicates the presence of osteoporosis and the need for appropriate medical care; once the treatment has been started, the doctor can evaluate its effectiveness by subjecting the patient to periodic bone densitometries.