Differential diagnosis of osteoporosis.

Background: Dual x-ray absorptiometry (DEXA) is widely used to identify persons at increased risk for osteoporotic fractures. It does not, per se, give us any diagnostic information that is necessary to determine the best therapeutic approach in an individual case.

Objective: Identify conditions and tests that may impact on the diagnosis and the treatment of subjects with low bone densitometry scores.

Subjects And Methods: We evaluated clinically, by history, physical examination and laboratory tests, 272 persons with low spinal and/or femoral bone absorptiometry for potential causes of osteoporosis.

Results: We found that 25.3% of the patients had significant underlying conditions: 17.9% had subclinical vitamin D deficiency (osteomalacia), 6.7% had hypercalciuria and 0.7% had primary hyperparathyroidism.

Conclusion: It is mandatory to go through a differential diagnosis in every case with absorptiometric data compatible with the diagnosis of osteoporosis. At the minimum, blood calcium and 25-hydroxyvitamin D and 24-hour urinary calcium excretion should be examined. This will allow the physician to determine the appropriate course of therapy in any individual patient who has abnormal DEXA findings.