Tubulointerstitial nephritis and uveitis syndrome in children: What to keep an eye on

Purpose: The purpose of this study was to determine the disease course in patients with tubulointerstitial nephritis and uveitis (TINU) syndrome, focusing on long-term outcome and the incidence of complications such as chronic kidney disease (CKD). Methods: We retrospectively analysed the recorded clinical characteristics of 32 children with TINU at their first presentation (baseline) and during a follow-up period of up to 27 months (range: 21–27 months). Results: The majority of patients (27/32; 84.4%) presented initially with ophthalmological symptoms. The most common initial ophthalmological presentation was anterior unilateral or bilateral uveitis, which in 23 patients progressed to chronic bilateral panuveitis. Patients who presented initially to their paediatrician with nephritis developed ocular symptoms within 4 months following the onset of nephritis. Inflammatory markers of active tubulointerstitial nephritis resolved more quickly than markers of active uveitis (p-value = 0.001). At 21–27 months, 7/23 patients (30.4%) had chronic kidney disease (CKD); moreover, these patients with CKD were significantly less likely to have received systemic corticosteroids at the onset of TINU compared to those without CKD (p-value = 0.045). Conclusion: Due to its heterogeneity in clinical presentation, all paediatric patients presenting with unilateral or bilateral uveitis should be screened for TINU. Likewise, patients who present with tubulointerstitial nephritis should be screened for the development of uveitis within the first several months. Ophthalmological outcome is favourable after long-term treatment with immunosuppressive medications. Finally, identifying tubulointerstitial nephritis early is important, as nearly one-third of cases can develop CKD and may therefore benefit from early treatment with corticosteroids.