Clinical Features of Tubulointerstitial Nephritis and Uveitis (TINU) Syndrome in Hokkaido, Japan

Purpose Although tubulointerstitial nephritis and uveitis (TINU) syndrome is considered to have a relatively good prognosis, its actual clinical features are not well understood. This study examined the clinical features of TINU syndrome cases that visited our hospital. Methods Patients who visited Hokkaido University Hospital and were diagnosed with TINU syndrome between 2004 and 2018 were included. Ocular findings, laboratory results, and treatment records were retrospectively reviewed from clinical charts. Results A total of 61 eyes from 31 patients were included: seven “definite” and 24 “probable” TINU cases. Age at first examination ranged from eight to 54 years (mean 16.0 years). Anterior uveitis was present in all eyes, while posterior segment inflammation was found in 79%, including vitreous haze, optic disc redness, dilated retinal vessels, retinal exudates, and serous retinal detachment. Urine β2-microglobulin was elevated in all patients, and serum soluble interleukin-2 receptor (sIL-2R) was elevated in 67%. Oral corticosteroids were required in 55% of patients, and recurrence occurred in 65%. Most cases achieved remission of uveitis by age 24. Final corrected visual acuity was 0.8 or better in 93% of patients, while 4% had 0.2 or worse. Conclusion More than three-quarters of cases showed not only anterior chamber inflammation but also posterior ocular inflammatory findings. Elevated sIL-2R was a reliable marker for TINU syndrome. Most cases achieved remission by adulthood and had a good visual prognosis, although some experienced poor outcomes due to ocular complications.