Tubulointerstitial Nephritis With Uveitis (TINU) Syndrome: A Case Series and Review of Literature.

Tubulointerstitial nephritis with uveitis (TINU) syndrome is a rare disorder characterised by the simultaneous or sequential occurrence of acute tubulointerstitial nephritis and uveitis, in the absence of systemic disease. Its true prevalence is likely underestimated, as renal and ocular manifestations may not appear concurrently. We conducted a retrospective case series of patients diagnosed with TINU at a single tertiary centre between 2016 and 2025. Clinical, biochemical, histopathological and ophthalmological data were reviewed. Long-term renal and ocular outcomes were assessed. Ten patients (female:male 6:4) were identified, with a median age at diagnosis of 41 years (range 15-67). Renal disease preceded uveitis in 60% of cases, with a mean interval of 5.6 months. At presentation, 70% had serum creatinine > 200 μmol/L and one patient required transient dialysis. All renal biopsies demonstrated tubulointerstitial nephritis with preserved glomeruli. All patients were treated with systemic corticosteroids, with topical therapy for uveitis. Renal relapse occurred in 60% of patients, often during steroid tapering, and required prolonged corticosteroid therapy or mycophenolate mofetil. At final follow-up (median 44 months), 50% had chronic kidney disease (eGFR < 60 mL/min). Relapsing disease was more frequent in females and patients under 18 years. At last follow-up, mean serum creatinine was 89 μmol/L, with 50% of patients having CKD G3a. Ophthalmologic data (n = 6) showed bilateral anterior uveitis in all cases, with intermediate involvement in three. Two developed steroid-induced intraocular hypertension. Ocular relapse occurred in six patients and frequently paralleled renal disease activity. We herein report one of the longest median follow-up durations (44 months) among biopsy-proven cohorts of interstitial nephritis. Our cohort spans a broader age range (15-67 years) than traditionally described with an adult predominance. Despite a 60% relapse rate, response to steroids and immunosuppression was good. Proteinuria at presentation was noted in individuals who developed subsequent CKD supporting the need for follow up and proteinuria management where relevant.