Serum urate level has recently been associated with increased bone mineral density (BMD). Teriparatide, an osteoanabolic medication for osteoporosis, is associated with increased incidence of hyperuricemia. Hence, we hypothesized that changes in serum urate are associated with changes in BMD and procollagen type 1 N-terminal propeptide (P1NP) during treatment with teriparatide.
We collected data from 151 women (mean age 72 years, mean BMI 26.6 kg/m2) with severe postmenopausal osteoporosis who had been treated with teriparatide for 2 years at our outpatient clinic. They were prescribed with vitamin D3 1000 IU daily and were instructed to ingest 1200 mg of calcium daily. BMD was measured at the three standard sites by DXA at baseline, after 12 and 24 months of treatment. Routine laboratory parameters (including serum urate), 25-hydroxyvitamin D and P1NP were measured at the same time-points. Estimated glomerular filtration rate (eGFR) was calculated. The associations were assessed using univariate correlations and multiple linear regression models (each fitted using casewise deletion of records with missing data as well as missing data imputation). Repeated-measures analysis of variance was used to verify the increase in serum urate level and stability of eGFR.
During the 2-year treatment with teriparatide, we observed no notable univariate association between change of serum urate level and change of BMD. When adjusting for basal eGFR, vitamin D sufficiency, previous bisphosphonate treatment, change of serum and of urinary calcium during the same period, we observed a weak positive association of serum urate level change with change of BMD at lumbar spine. Conversely, change of serum urate level tended to be weakly positively univariately associated with change of P1NP, but the association vanished when adjusting for the confounders listed above.
Our results may indicate that the effect of teriparatide on bone might be partly mediated by changes in serum urate level.
20 - 23 May 2017
European Society of Endocrinology