Long-term outcome of biopsy-proven idiopathic tubulointersitial nephritis with or without uveitis in children—a nationwide follow-up study

BACKGROUND: Only a few studies reporting the long-term outcome of children with idiopathic tubulointerstitial nephritis (TIN) and uveitis syndrome (TINU) are available. We studied the long-term kidney and ocular outcome in a nationwide cohort of children with TIN or TINU. METHODS: All patients followed up for a minimum of 1 year by a paediatrician and an ophthalmologist were enrolled. The data on plasma creatinine (P-Cr), estimated glomerular filtration rate (eGFR), proteinuria, hypertension and uveitis were collected retrospectively. RESULTS: Fifty-two patients were studied. Median age at time of diagnosis was 13.1 (1.8–16.9) years and median follow-up time was 5.7 (1.1–21.2) years. Forty-five (87%) patients were initially treated with glucocorticoids. The median of the maximum P-Cr was 162 μmol/l (47–1,016) and that of eGFR 47 ml/min/1.73m(2) (8–124). Uveitis was diagnosed in 33 patients (63%) and 21 (40%) patients developed chronic uveitis. P-Cr normalised in a median of 2 months. Eleven (21%) patients had nephritis recurrence during or after discontinuation of glucocorticoids. At the latest follow-up, 13 (25%) patients had eGFR < 90 ml/min/1.73m(2) (median 83; 61–89 ml/min/1.73m(2)). Six patients had tubular proteinuria; all presented with TIN without uveitis. Seven (13%) patients were hypertensive. Eleven (21%) patients had uveitis. One patient developed uraemia and was later transplanted. CONCLUSIONS: Our study questions the previously reported good long-term kidney and ocular outcome of patients with TIN/TINU. Decreased kidney function and/or ocular co-morbidities may persist for several years; thus, both kidney and ocular follow-up for at least 1 year is warranted. GRAPHICAL ABSTRACT: A higher resolution version of the Graphical abstract is available as Supplementary information [Image: see text] SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s00467-021-05060-5.