What is indicated by a T-score of -2.8 on a DEXA scan?

Appeared in: BTSC Staff Nurse 30July-2025

Explanation

A T-score of -2.8 falls into the category of -2.5 or lower, which is the diagnostic criterion for osteoporosis according to the World Health Organization (WHO).
The T-score compares a person's bone mineral density (BMD) to the average BMD of a healthy young adult.
A negative score indicates that the bone density is lower than that of a healthy young adult; a score below -2.5 signifies a pathologically low level, increasing fracture risk significantly.

Option A: A T-score of -2.8 indicates significantly decreased bone density, not increased. Increased bone density would be represented by a positive T-score.
Option B: Normal bone density is defined by a T-score of -1.0 or higher. The score of -2.8 is well below this range.
Option D: Osteopenia, or low bone mass, is defined as a T-score between -1.0 and -2.5. While -2.8 indicates low bone mass, it is severe enough to be classified as osteoporosis.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Interpretation of DEXA scan T-scores for diagnosing osteoporosis as background academic context rather than a clinical decision trigger.
Nurses play a crucial role in educating patients with osteoporosis about fall prevention strategies, the importance of weight-bearing exercises, and adequate intake of calcium and vitamin D to reduce fracture risk.
A diagnosis of osteoporosis often prompts initiation of pharmacotherapy (e.g., bisphosphonates) to slow bone loss and reduce fracture incidence.
What if? If the T-score was -2.0, the diagnosis would be osteopenia, not osteoporosis. The management would focus on lifestyle modifications to prevent progression to osteoporosis, rather than immediately starting potent antiresorptive medications which are typically reserved for osteoporosis.

How to Approach the Question

First, identify the key value in the question: T-score of -2.8.
This is an analytical question that requires recalling the standard diagnostic ranges for bone density.
Recall the WHO classification for T-scores: Normal (greater than or equal to -1.0), Osteopenia (-1.0 to -2.5), and Osteoporosis (less than or equal to -2.5).
Compare the given value (-2.8) to these ranges.
Since -2.8 is lower than -2.5, it falls into the osteoporosis category.
Select the option that matches this diagnosis.

Concept Tested & Keywords

Concept Tested: Interpretation of DEXA scan T-scores for diagnosing osteoporosis.
Stem keywords: T-score, -2.8, DEXA scan
Lead-in keywords: indicated by
Clinical cues: A T-score of -2.8 signifies a value that is more than 2.5 standard deviations below the young adult mean.

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E6 Gynecology Williams p. 73-96

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Practise the full BTSC Staff Nurse 30July-2025

Attempt every question from this paper in a timed mock, then review the full solution for each one.