Abstract
5-Amino salicylic acid (5-ASA) is a known culprit for the development of tubulointerstitial nephritis. Together with impaired kidney function, tubulointerstitial nephritis can lead to specific tubular malfunctions including distal renal tubular acidosis. Distal renal tubular acidosis is an acid-base disorder in which acid secretion in the distal part of the renal tubular system is decreased. Patients with distal renal tubular acidosis are predisposed to recurrently form calcium phosphate kidney stones. This results from the inability to acidify the urine properly as well as from a decreased citrate concentration in the urine, which is another pathognomonic feature of distal renal tubular acidosis. We present the case of a man in his late 40s with Crohn's disease who developed tubulointerstitial nephritis associated with 5-ASA leading to the development of distal renal tubular acidosis and recurrent calcium phosphate nephrolithiasis. After steroid therapy and partial recovery of kidney function, we observed an increase of citraturia in response to treatment with dapagliflozin, potentially indicating beneficial effects of sodium/glucose cotransporter 2 inhibition on the recurrence of calcium phosphate stone disease in interstitial nephritis-induced distal tubular acidosis.