Definition
TINU (tubulointerstitial nephritis with uveitis) syndrome is a rare disorder combining acute interstitial nephritis with uveitis, once other causes have been excluded. It has a predilection for adolescents and young women.
Pathophysiology
The precise mechanism is uncertain but is thought to be immune-mediated, with a shared antigenic trigger provoking inflammation in both the renal interstitium and the uveal tract. Some cases follow infections or drug exposure.
Clinical presentation
- Renal: features of acute interstitial nephritis — acute kidney injury, sterile pyuria, sub-nephrotic proteinuria
- Ocular: anterior uveitis, often bilateral, causing a red painful eye, photophobia and blurred vision; it may be recurrent
- Systemic: fever, weight loss, fatigue and anorexia are common
- The uveitis may precede, coincide with, or follow the nephritis by months
Investigations
- Rising creatinine with a tubulointerstitial urinary picture
- Raised inflammatory markers (ESR), anaemia, and sometimes eosinophilia
- Elevated urinary β2-microglobulin reflects tubular injury
- Slit-lamp examination confirms anterior uveitis
- Renal biopsy shows interstitial nephritis
Management
- Corticosteroids — topical for the uveitis and systemic (oral) therapy for significant renal involvement
- Treat/withdraw any precipitant; ophthalmology and nephrology co-management
- Renal prognosis is generally good, though uveitis may relapse and require prolonged ophthalmic follow-up
MRCP-specific traps
- Consider TINU in a young patient with unexplained AKI and a red eye — the two are easily treated as separate problems.
- The uveitis can appear after the kidney has recovered, so warn patients and arrange eye follow-up.
Summary
TINU is interstitial nephritis plus (often recurrent) anterior uveitis, typically in young women, with systemic upset. Steroids treat both; the kidney usually recovers but the eyes need ongoing surveillance.
nephrologyophthalmologyautoimmunemrcp part 2