Understanding Bone Densitometry and Osteoporosis

Bone densitometry is an instrumental technique to assess the mineral density of bones, thereby making it a valuable tool in diagnosing and monitoring osteoporosis.

Osteoporosis: An Overview

Osteoporosis is a skeletal disorder marked by a decrease in bone mineral content and a deterioration of the bone's microstructure. This condition increases the patient's susceptibility to fractures, even from minor traumas. The risk of fractures is directly proportional to the decrease in bone mass. Thus, bone densitometry serves as a vital diagnostic tool and a predictor of fracture risk in osteoporosis.

Bone Densitometry: How Does It Work?

Bone densitometry employs a minimal dose of X-rays to measure the amount of calcium and other minerals present in a particular bone segment. The radiation doses are so minimal that even frequent examinations do not pose any health risk to the patient.

Among the various types of equipment used, Dual-energy X-ray absorptiometry (DEXA) is the most commonly used.

Execution and Preparation

The entire process of bone densitometry is swift, taking approximately ten minutes. It is a painless procedure, and patients do not require any specific dietary or pharmacological preparations. Post-examination, patients can resume their regular activities.

However, if a patient has recently undergone a scintigraphic or radiological examination with a barium contrast medium, the densitometry should be postponed for a few days. Additionally, any metal objects such as coins, buckles, watches, and bracelets should be removed from the examination field.

Examined Locations

The bone segments examined during bone densitometry depend on the patient's characteristics. Generally, the lumbar spine is evaluated in younger women (under 65 years), while the femoral neck is examined in older women and those with spinal pathologies. Sometimes, the examination may be conducted on both segments or at the radius (forearm).

Who Should Undergo Bone Densitometry?

Bone densitometry is highly recommended for individuals with significant risk factors for osteoporosis, which include:

  • Women aged over 65 years and those who have been in menopause for at least a decade.
  • Early menopause (before 45 years).
  • Surgical menopause (removal of the ovaries during the fertile period).
  • Various causes of estrogen deficiency.
  • Constitutional factors that predispose to osteoporosis.
  • Significant nutritional deficiencies (inadequate intake of calcium and vitamin D).
  • Symptoms that suggest the presence of osteoporosis.
  • Prolonged treatments with high-dose cortisone drugs or other osteopenic drugs.
  • Previous fractures not due to significant trauma.
  • Diseases that favor bone demineralization.
  • Strong positive family history for osteoporosis.
  • Smoking more than 20 cigarettes a day, alcohol abuse.

If one or more of these risk factors are present, it is crucial to consult a healthcare professional to consider undergoing bone densitometry.

Interpreting the Results

The diagnosis of osteoporosis is based on the comparison of the densitometric result with the average result of healthy adult subjects of the same sex and aged 25-30 years (T-score) and/or the average result of subjects of the same age and sex (Z-score).

As per the World Health Organization (WHO), the diagnosis of osteoporosis should be conducted, limited to the DEXA technique, considering the densitometric values, expressed in T-score as follows:

  • T-score > -1: Normal bone health
  • T-score < -1 and > -2.5: Osteopenia
  • T-score < -2.5: Osteoporosis
  • T-score < -2.5 with fracture: Severe Osteoporosis

A T-score equal to 0 indicates that the examined subject has a bone density equal to the average of young individuals, while a T-score equal to or greater than -1 is still considered normal. If a T-score is between -1 and -2.5, the subject has reduced bone density, which is not severe enough to be considered osteoporosis but is significant enough to necessitate an effective treatment plan to prevent further bone demineralization. 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 initiated, the doctor can evaluate its effectiveness by subjecting the patient to periodic bone densitometry.

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