Non-invasive assessment of bone density in primary biliary cirrhosis

Low bone mass is an important complication of primary biliary cirrhosis (PBC), resulting in an increased risk of fractures and reduced mobility. In the present study, we sought to determine the frequency of low bone mass in PBC, and its relationship to disease severity and non-invasive markers of bone turnover.

In 36 women with PBC, bone mineral density of the lumbar spine and hip was assessed by dual emission X-ray absorptiometry. Serum and urinary markers of bone turnover were compared with those from age- and sex-matched controls.

Spinal osteopenia (T score, -1.5 to -2.5) was present in 15 of the 36 patients (42%), while six others (16%) had established osteoporosis (T < -2.5). Osteopenia of the femoral neck was found in 17 patients (47%), and osteoporosis in five (14%). The severity of liver disease, as determined by Mayo Clinic R score and histological stage, correlated negatively with both regional bone mineral density and total bone mineral content expressed as a ratio to lean body mass. There was a strong positive correlation between serum levels of the procollagen degradation peptides, PICP and PIIINP (r = 0.65, P < 0.001), and both peptides correlated significantly (P < 0.001) with histological stage and Mayo Clinic R score. Fasting urinary pyridinoline and deoxypyridinoline to creatinine ratios were also significantly raised.

Low bone mass in PBC correlates positively with disease severity, and is associated with a net increase in bone resorption, as assessed by urinary collagen cross-link excretion. These markers of bone turnover may be of value in controlled clinical trials aimed at improving bone mass in PBC.