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

BACKGROUND: Acute 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. METHODS: Cases were identified retrospectively from departmental records. Data extracted included demographics, presenting clinical and biochemical features, renal biopsy histology, treatment and follow-up. RESULTS: Ten 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/1.73m(2) (range 51-103 ml/min/1.73m(2)). 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/1.73m(2), range 63 to 101 ml/min/1.73m(2)). 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). CONCLUSION: To 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 < 90 ml/min/1.73m(2) at last follow-up. We suggest a standardised investigative work-up and recommend long-term follow-up.