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Kidney Week

Abstract: FR-PO204

Tubulointerstitial Nephritis and Uveitis Syndrome (TINU)

Session Information

Category: Acute Kidney Injury

  • 103 AKI: Mechanisms

Authors

  • Hasan, Alina, Corewell Health, Royal Oak, Michigan, United States
  • Abu-Khaled, Jamal, Corewell Health, Royal Oak, Michigan, United States
  • Alam, Anusha, Corewell Health, Royal Oak, Michigan, United States
  • Pothugunta, Krishna, Corewell Health, Royal Oak, Michigan, United States
Introduction

Tubulointerstitial Nephritis and Uveitis Syndrome (TINU) is a rare, self-limiting interstitial nephritis and bilateral anterior uveitis.1 Here, we describe an interesting case of TINU.

Case Description

A 42-year-old woman with no significant medical history presented to the hospital with acute kidney injury (AKI). She was noted to have elevated creatinine (Cr) of 2.2mg/dL with a baseline of 0.7-0.9mg/dL. Urinalysis was positive for blood (3+) and protein (30 mg). She reported using naproxen for menstrual cramps. Physical exam was negative for skin rash or lower extremity edema. Family history was significant for sarcoidosis. During inpatient stay, labs revealed urine protein to creatinine ratio (Pr:Cr) was 0.97 g/g. Serological work up was negative for ANA, ANCA, anti GBM, MPO, PR-3 and PLA2R. Complement levels were normal. Serum protein electrophoresis (SPEP) was negative for monoclonal protein. Free light chain ratio was elevated but acceptable for renal function. Urine eosinophils were negative. Kidney ultrasound (US) showed normal sized kidneys with normal echotexture and no evidence of hydronephrosis. Kidney biopsy showed acute interstitial nephritis. She received prednisone 60 mg daily which was tapered over 4 weeks. Cr improved to 1mg/dl on outpatient labs. She developed anterior uveitis after tapering the steroids and was prescribed methyl prednisone by ophthalmology. Repeat urinalysis showed significant pyuria with no nitrites nor proteinuria and Pr:Cr at 0.19 g/g. Repeat SPEP was negative. IgG4 subclasses were normal. Sjrogen antibodies, HLA B27 screening, Lyme’s serology, quantiferon TB were all negative. ACE levels and 1,25 vit D levels were normal. Previous chest x-ray was negative for any hilar lymphadenopathy. Repeat renal biopsy showed resolving tubulointerstitial nephritis, however increased chronicity with moderate interstital fibrosis compared to mild previously.

Discussion

TINU is a diagnosis of exclusion2,3 confirmed with renal biopsy. Management includes steroids with some severe cases requiring steroid sparing immunomodulators. Recurrence is common in the 1st few months to 2 years of stopping therapy.3 Conclusion: An unexplained AKI that has been thoroughly worked up, in the presence uveitis, should prompt consideration for TINU, especially if it’s been steroid responsive and recurring after its discontinuation.