Acute tubulointerstitial nephritis in children– a retrospective case series in a UK tertiary paediatric centre

BackgroundAcute tubulointerstitial nephritis (AIN) is an uncommon cause of acute kidney injury in children, accounting for less than 10% of cases. There is limited information regarding the range of underlying diagnoses and how these may differ geographically.We undertook a retrospective case note review of consecutive cases of biopsy-proven AIN, presenting to a single UK tertiary paediatric centre, to describe the range of AIN in our caseload, define key characteristics and response to treatment, with the aim of informing paediatric nephrology practice.MethodsCases were identified retrospectively from departmental records. Data extracted included demographics, presenting clinical and biochemical features, renal biopsy histology, treatment and follow-up.ResultsTen cases were identified over 8 years (2007–2014). Age range 6–16 years. Male:Female ratio 1:9. Final diagnoses included 6 tubulointerstitial nephritis and uveitis syndrome (TINU), 2 idiopathic, 1 sarcoidosis, 1 child with Streptococcal disease. Of the TINU cases, timing of eye symptoms varied in relation to AIN presentation. Cases had a varied investigative work-up.Median presenting plasma creatinine was 303 μmol/l (range 152–932 μmol/l). Renal function improved spontaneously in 1 idiopathic case and improved with antimicrobial treatment in a child with Streptococcal disease.Eight cases received immunosuppressive treatment with intravenous methylprednisolone (approximately 10 mg/kg for 3–5 days) and / or oral prednisolone (1–2 mg/kg initially, reducing over 7–28 days).At 1 month, median creatinine had fallen to 91 μmol/l (range 41–120 μmol/l) with median eGFR 61 ml/min/1.73m2(range 51-103 ml/min/1.73m2). At last follow-up (median 18.5 months, range 2–70 months), median creatinine was 71 μmol/l (range 47–90 μmol/l) with median eGFR 80 ml/min/1.73m2, range 63 to 101 ml/min/1.73m2).Two patients received antihypertensives at diagnosis and 1 further patient at 1 month follow-up. Eight patients received electrolyte supplementation. Median time to discontinuing electrolyte supplementation was 3.5 months (range 1–12 months).ConclusionTo our knowledge, this is the only contemporary UK case series of biopsy-proven AIN in children. Our population has a high proportion of TINU. Treatment was accompanied by improvement of renal function, however 7/10 patients had an eGFR 2at last follow-up. We suggest a standardised investigative work-up and recommend long-term follow-up.