The mineral content in the bone can be calculated by?

DSSSB - 29 August 2019 (Shift-1)

Applied Physiology

Easy

Appeared in: DSSSB - 29 August 2019 (Shift-1)

Explanation

Dual-energy X-ray Absorptiometry (DEXA) is the preferred and most accurate method for measuring bone mineral density (BMD).
It works by passing two low-dose X-ray beams with different energy levels through the bone.
The machine calculates BMD by measuring the differential absorption of these beams by bone and soft tissue, providing a precise value.
DEXA is the established gold standard for diagnosing osteoporosis and assessing fracture risk, particularly at the hip and spine.

Option A: Standard X-rays are not sensitive enough to detect early bone loss. Significant demineralization (often greater than 30%) must occur before it becomes visible on a conventional X-ray.
Option C: Ultrasound provides a qualitative assessment of bone structure but is not as precise as DEXA for quantifying mineral density. Its results are not used for definitive diagnosis.
Option D: A spectrometer is an instrument used to measure the properties of light over a specific portion of the electromagnetic spectrum. It has no application in measuring bone mineral content.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Diagnostic methods for measuring bone mineral density (BMD) as background academic context rather than a clinical decision trigger.
Nurses play a key role in educating patients about osteoporosis screening. Understanding that DEXA is the gold standard helps in providing accurate patient teaching and preparing them for the procedure.
Accurate BMD measurement is crucial for determining a patient's 10-year fracture risk using tools like the FRAX score, which guides treatment decisions.
Patient preparation for a DEXA scan is minimal. Nurses should instruct patients to avoid taking calcium supplements for 24 hours before the test and to wear loose clothing without metal zippers or buttons.

How to Approach the Question

First, identify the core of the question, which is asking for the standard method to 'calculate' bone mineral content.
Evaluate each option based on its function in medical diagnostics.
Recognize that 'X-rays' are primarily for viewing fractures and dense structures, but not for precise quantification of density.
Recall or deduce that 'Ultrasound' uses sound waves and is often used for screening soft tissues or, in this context, as a preliminary bone assessment.
Eliminate 'Spectrometer' as it is a laboratory instrument for analyzing light, unrelated to bone imaging.
This leaves 'Dual energy x-ray absorptiometry,' which by its name suggests a quantitative measurement ('absorptiometry') using X-rays. This is the most specific and technically correct answer for calculating bone density.

Concept Tested & Keywords

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