Biopsy-proven paediatric tubulointerstitial nephritis.

BACKGROUND: Tubulointerstitial nephritis (TIN) is an uncommon condition in which the aetiology, treatment and outcome is not well defined. We describe a large series of children with biopsy-proven TIN.

METHODS: All children with biopsy-proven TIN presenting to our institution during a 23-year period were retrospectively reviewed for aetiology, symptoms, treatment, and long-term outcome.

RESULTS: A total of 27 children (16 girls) were described. Median age was 12 years (range 8 months to 15 years). A potentially adverse drug reaction was found in 12 (44 %) and infection in 8 (30 %). In 13 (48 %) no initiating factor was identified. All but 1 patient were treated with corticosteroids owing to worsening kidney function and 4 patients with other immunosuppressive agents. Fifteen children (56 %) had an estimated glomerular filtration rate (eGFR) of less than 80 ml/min/1.73 m(2) at last follow-up. Fifteen of the 23 children investigated (65 %) had coexistent uveitis.

CONCLUSION: This series represents a subset of paediatric TIN patients in whom there was a clinical indication for a renal biopsy, hence presenting with more severe disease than previously reported. This group were more likely to have no identifiable underlying cause and an increased requirement for corticosteroid treatment. Furthermore, more than half of the cases developed chronic kidney disease (CKD) with impaired kidney function.