Renal tubular acidosis, Sjögren syndrome, and bone disease.

BACKGROUND: There has been disagreement about whether osteomalacia (adult rickets) occurs in adults with type 1 (distal) renal tubular acidosis (RTA1). Therefore, after finding scapular pseudofractures in a patient with RTA1 and Sjögren syndrome, we decided to survey other patients with RTA to learn whether osteomalacia occurred in others and, if it did, whether it was necessarily associated with the presence of Sjögren syndrome.
METHODS: We examined the hospital records and laboratory findings of 250 patients with codes for RTA, 124 with codes for osteomalacia, and 20 with codes for Sjögren syndrome who were seen at a university-affiliated acute care municipal hospital since 1990. Further detailed survey was then limited to patients older than 15 years and excluded those with potentially confounding causes of bone disease such as chronic renal insufficiency or sickle cell disease. Seven adults with RTA1 were thereby identified.
RESULTS: Two adults with RTA1 had radiological and biochemical findings compatible with osteomalacia, and 1 had findings compatible with Sjögren syndrome. A third patient without Sjögren syndrome had biochemical findings suggestive of osteomalacia.
CONCLUSIONS: Osteomalacia seems to occur in some adult patients with RTA1, and not only in association with Sjögren syndrome. We found no biochemical evidence of osteomalacia in the patients with Sjögren syndrome who did not have RTA.