[Bone mineral density and bone turnover in systemic sclerosis]

To elucidate bone mineral density (BMD) and bone turnover in an un-selected group of patients with Systemic Sclerosis (SSc) in national based registry.

All patients who have been diagnosed with SSc in Iceland were invited to participate in the study. Participants underwent standardized interview and delivered urine and blood samples for measurements of various bone metabolites (e.g. PTH, osteocalcin, Cross Laps, PINP, IGF-1, Cystatin-C and 25-OH-vitamin-D), before they underwent measurement of BMD with DEXA (QDR 4500 Elite).

Twenty-four individuals, 20 female and four male, of 29 diagnosed patients with SSc in Iceland accepted to participate in the study (83%). The mean age was 60 +/- 15 years. Seventeen of 20 females were postmenopausal. Twelve patients had history of fractures. Only four patients were on treatment with bisphosphonate. All measured bone metabolites were in normal ranges, but U-calcium was in the lower ranges. According to DEXA, eight patients had osteopenia (T-value = -1.0 - -2.5) and three osteoporosis (T-value <---2.5), while six patients had BMD more than one standard deviation below the mean of age matched controls.

Although the majority of patients with SSc have normal bone turnover and BMD, every fourth patient may have low BMD. No single pathogenic factor was observed, however, several individuals are in calcium saving stages reflected in low urinary calcium excretion. This may be result of defects in intestinal absorption of calcium due to gastrointestinal involvement of the disease. This study does not give opportunity to evaluate effects of treatment on BMD in this group of patients. Thus, individual evaluation concerning osteoporosis is recommended in patients with SSc.