Primary Sjögren’s syndrome (pSS) can be complicated by distal renal tubular acidosis (dRTA), which may contribute to low bone mineral density (BMD). Our objective was to evaluate BMD in pSS patients with and without dRTA as compared with healthy controls. BMD of lumbar spine (LS) and femoral neck (FN) was measured in 54 pSS patients and 162 healthy age- and sex-matched controls by dual-energy X-ray absorptiometry (DXA). dRTA was defined as inability to reach urinary pH <5.3 after an ammonium chloride (NH4Cl) test. LS- and FN-BMD were significantly higher in pSS patients compared with controls (1.18 ± 0.21 g/cm2 for patients vs. 1.10 ± 0.18 g/cm2 for controls, P = 0.008 and 0.9 ± 0.16 g/cm2 for patients vs. 0.85 ± 0.13 g/cm2 for controls, P = 0.009, respectively). After adjustment for BMI and smoking, the LS- and FN-BMD remained significantly higher. Patients with dRTA (N = 15) did not have a significantly different LS- and FN-BMD compared with those without dRTA (N = 39) after adjustment for BMI, age, and gender. Thirty-seven (69 %) pSS patients were using hydroxychloroquine (HCQ). Unexpectedly, pSS patients had a significantly higher LS- and FN-BMD compared with healthy controls. Patients with dRTA had similar BMD compared with patients without dRTA. We postulate that an explanation for the higher BMD in pSS patients may be the frequent use of HCQ.

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Calcified Tissue International
Department of Immunology

Both, T., Zillikens, C., Hoorn, E., Zietse, B., van Laar, J., Dalm, V., … van Daele, P. (2016). Bone Mineral Density in Sjögren Syndrome Patients with and Without Distal Renal Tubular Acidosis. Calcified Tissue International, 98(6), 573–579. doi:10.1007/s00223-016-0112-z