Tubulointerstitial nephritis and uveitis (TINU) syndrome: a case series.

Purpose: Tubulointerstitial nephritis and uveitis (TINU) syndrome, characterised by the co-occurrence of tubulointerstitial nephritis and uveitis in the absence of other systemic diseases, presents a diagnostic challenge due to its non-specific symptoms. This case series aims to shed light on TINU syndrome's clinical features, underlying causes, and management strategies. The prevalence of TINU syndrome is relatively low with estimates of 3.5 cases/ million people with an incidence of 0.2 cases/ million/ year and it often goes underdiagnosed. The ratio of males to females reported was 4:1. Histological confirmation through renal biopsy is crucial, while systemic conditions such as systemic lupus erythematosus, tuberculosis, sarcoidosis, and Sjogren's disease should be excluded. In most cases, TINU appears to be an idiopathic immune-mediated process, but it may be precipitated by drugs or infections. Antibiotics and non-steroidal anti-inflammatory drugs (NSAIDs) have been associated with some cases of TINU syndrome. Genetic markers, particularly HLA subtypes, have shown a strong association with TINU syndrome. Uveitis which is characterised by intraocular inflammation is a common feature of TINU syndrome. Anterior uveitis, the most prevalent form, presents with symptoms such as red eye, eye pain, photophobia, and keratic precipitates which are subdivided into granulomatous and non-granulomatous. Corticosteroids represent the primary treatment for ocular inflammation, while immunosuppressant medications may be employed for treatment of nephritis.

Observations: Through the analysis of five TINU syndrome cases, this case series provides insights into the clinical presentations, laboratory findings, and biopsy results of patients with TINU syndrome. The cases include individuals with associated systemic conditions such as asthma, psoriasis and hyperthyroidism.

Conclusion and importance: In conclusion, TINU syndrome is a rare condition characterised by the simultaneous occurrence of tubulointerstitial nephritis and uveitis. Increased awareness among healthcare professionals is necessary for early recognition and appropriate management of this syndrome. Further research is needed to elucidate the pathogenesis, optimise diagnostic criteria, and explore more targeted therapeutic approaches for TINU syndrome.