Background and Objectives Diagnostic discordance for osteoporosis is the observation that the T-score of an individual patient varies from one key measurement site to another, falling into two different diagnostic categories of minor and major discordances, identified by the World Health Organization (WHO) classification system. The aim of the present study was to assess the frequency of causes of minor discrepancy between bone densities of hip and spine.

Methods In this study, from all patients referred to bone marrow densitometery centre of Loghman from September 2008 to May 2009 in order to BMD assessment due to several causes and underwent spine and hip BMD. 171 cases with minor discrepancies were enrolled and causes of discrepancies were determined.

Results The mean age of patients was 92.69 ± 13.13 years. 87.78% of patients were female. The causes of minor discrepancy were respectively Osteoarthritis (45.03%), Osteoporosis (28.65%), Aortic Calcification, Osteoarthritis Deformans, Syndesmophytes and DISH each with 2.92%. These causes in female gender were Osteoarthritis (48.67%), Osteoporosis (27.33%), Aortic Calcification and Syndesmophytes with 3.33%; and in male they were Osteoarthritis (38.1%), Osteoporosis and DISH each with 19.05%.

Conclusions The minor discrepancy in T-score is a common finding which can result diagnostic problems in densitometry analysis. The results of the present study show that the most common causes of minor discrepancy were Osteoarthritis, Osteoporosis, Aortic Calcification, Osteoarthritis Deformans, Syndesmophytes and DISH.