Which bone is primarily used for the diagnosis in a forearm DXA scan?

• A. Ulna
• B. Fibula
• C. Radius
• D. Humerus

Answer: (C)

The radius is primarily used for diagnosis in a forearm DXA (Dual-energy X-ray Absorptiometry) scan because it is one of the major bones in the forearm that contributes significantly to overall bone density assessment. The radius, particularly the distal radius, is known to be more susceptible to osteoporosis and fractures, making it a critical site for evaluation.

In clinical practice, the measurement of bone mineral density at the radius can provide valuable information about an individual’s bone health, as this area tends to reflect the changes in bone density related to age, hormonal changes, and other risk factors for osteoporosis. The use of the radius allows for efficient detection of reduced bone mass, which is essential in diagnosing osteoporosis and assessing fracture risk.

In contrast, while the ulna and fibula are present in the forearm, they do not provide the same level of clinical significance for bone density evaluation compared to the radius. The humerus, though an important bone in the upper limb, is not typically the focus of forearm DXA scanning, as it lies more proximal and is not considered a primary site for forearm osteoporosis assessment. Therefore, the radius is the preferred site for diagnosis in this context.