A 65-year-old woman presents with severe mid-back pain of 2 weeks duration. She has no history of trauma. Radiographic evaluation reveals compression fractures of T11 and T12. A complete blood count, erythrocyte sedimentation rate, serum protein, serum calcium, phosphate, and parathyroid hormone levels are all within normal ranges. In addition to ordering a dual-energy x-ray absorptiometry (DEXA) scan, which of the following laboratory evaluations is most helpful in evaluating this patient for secondary causes of this presentation?(A) bone biopsy(B) rheumatoid factor(C) serum magnesium(D) 25-hydroxyvitamin D(E) antinuclear antibodies test

The patient has typical findings associated with the osteoporosis. Most of the patients who has osteoporosis are asymptomatic until fractures present.

Fractures occur spontaneously and are usually associated with back pain of varied degree.

The levels of parathyroid hormone, serum calcium and phosphate is normal. As vitamin D deficiency is common in osteoporosis, 25-hydroxyvitamin D should be ordered.