Metabolic bone disease as a presenting manifestation of primary Sjögren's syndrome: Three cases and review of literature

Primary Sjögren's syndrome (pSS) is a chronic autoimmune disease characterized by a progressive lymphocytic infiltration of the exocrine glands with varying degrees of systemic involvement. Chronic inflammation compromises the glands' function that leads to dry symptoms in the mouth/eyes. Renal involvement is a well recognized extraglandular manifestation of pSS. Metabolic bone disease (MBD), however, rarely occurs as the primary manifestation of a renal tubule disorder due to pSS. To the best of our knowledge there are only 6 reported cases of metabolic bone disease as the primary manifestation of pSS to date. Four of these had distal renal tubular acidosis (RTA), and 2 had a combined picture of distal and proximal tubular dysfunction. We herein present our experience of 3 cases who presented to us with a clinical picture suggestive of MBD. While investigating these patients, we found evidence of RTA, which was found to be secondary to pSS.