Ultrasound measurements of calcaneus for estimation of skeletal status in patients with inflammatory bowel disease.

BACKGROUND

Patients with inflammatory bowel disease (IBD) are at risk of developing metabolic bone disease. In diagnosing osteoporosis, bone mineral density (BMD) measurements play a key role. Our aims in this study were to assess the skeletal status with quantitative ultrasound (QUS) and to evaluate the ability of this method to predict BMD as measured by dual-energy X-ray absorptiometry (DXA) in IBD patients.

METHODS

Altogether 53 patients with Crohn disease (CD) and 57 with ulcerative colitis (UC) were studied by using a Lunar Achilles ultrasound bone densitometer. The ultrasound variables are broadband ultrasound attenuation (BUA) and speed of sound (SOS). The lumbar spine, femoral neck, and total body BMD were measured with DXA. The age- and sex-adjusted values (Z-scores) were obtained by comparison with age- and sex-matched normal values.

RESULTS

In CD patients Z-scores for both BUA and SOS were significantly less than zero, and Z-score for SOS was significantly lower than that for UC patients. Z-scores for BMD measured with DXA were significantly lower at all measurements in patients with CD. QUS and DXA measurements were significantly correlated. However, the agreement between the measurements in each individual patient was poor. Body mass index (BMI) was a major determinant for both BUA and SOS. In CD patients low QUS variables were associated with corticosteroid therapy, and both CD and UC patients with previous fractures had low SOS values.

CONCLUSIONS

Our study indicates that QUS and DXA are not interchangeable methods for estimation of bone status. QUS variables are insufficient to provide accurate prediction of BMD values and should therefore not be recommended as a screening test for osteoporosis in IBD patients.