Urinary 2-microglobulin and disease activity in patients with tubulointerstitial nephritis and uveitis syndrome

BackgroundUrinary 2-microglobulin (U2M) is elevated in tubulointerstitial nephritis and uveitis (TINU) syndrome and has emerged as an important diagnostic tool. This study aims to determine whether U2M correlates with uveitis activity in TINU.MethodsRetrospective observational case series of nine patients with TINU and 30days follow-up. Presenting symptoms, visual acuity, uveitis characteristics, follow-up, U2M, serum creatinine (SCr), urinalysis, and renal biopsy results were collected.ResultsA correlation between U2M and anterior chamber (AC) cell (r=0.69, 95% CI 0.46-0.84), flare (r=0.65, 95% CI 0.39-0.81), trended toward a stronger correlation than SCr and AC cell (r=0.59, 95% CI 0.29-0.79), flare (r=0.52, 95% CI 0.19-0.75). U2M decreased over 1-2years while SCr returned to normal within a few months.ConclusionsU2M correlate with uveitis activity and trend down over the course of TINU. U2M may serve as a useful tool in determining where patients are in their systemic disease course.