Abstract We describe the case of a 46-year-old woman with Sjogren's syndrome (SS) presenting with a 6-year history of polyuria and polydipsia. Laboratory data revealed hyperchloremic metabolic acidosis, a normal anion gap, and an inability to acidify urine following an acid loading test and to concentrate the urine in response to water deprivation and antidiuretic hormone administration. Lymphocyte infiltration in the interstitium was found on renal biopsy. These findings allowed us to diagnose distal renal tubular acidosis (RTA) and nephrogenic diabetes insipidus (NDI). Steroid pulse therapy resulted in normalization of the blood pH, but failed to remit the inability to concentrate the urine. These observations suggest therapeutic applications for RTA in SS, and that further investigation is required to design a therapeutic strategy for NDI in SS.
