Tubulointerstitial nephritis and uveitis in children and adolescents. Four new cases and a review of the literature

Tubulointerstitial Nephritis and Uveitis Syndrome in Pediatric Patients

Tubulointerstitial nephritis and uveitis (TINU) syndrome is a disorder that was originally described in 1975. The syndrome, although diagnosed in all age ranges, is more frequently reported in pediatric patients. Diagnosis can be difficult, and its clinical spectrum is still being defined. In this article, we review the epidemiology, diagnosis, pathogenesis, clinical findings, prognosis, and treatment of both the ocular and renal disease. We comment on the current difficulties in diagnosis and study of the disease, its expanding clinical spectrum, and treatment strategies in pediatric patients.

Diagnostic and Management Strategies of Tubulointerstitial Nephritis and Uveitis Syndrome (TINU): Current Perspectives

Tubulointerstitial nephritis and uveitis (TINU) syndrome is a rare autoimmune disease with unclear pathogenesis but probably related to a combination of genetic predisposition and environmental triggers. Diagnosis is challenging due to the asynchronous onset of renal and ocular symptoms, and it is necessary to exclude other causes of nephritis and uveitis. It affects both sexes, with an overall predominance of females and a median age of onset of 15 years. TINU syndrome is characterized by bilateral, non-granulomatous anterior uveitis and tubulointerstitial nephritis, which can cause acute renal failure in severe cases. Several triggers have been identified including concurrent infections, medications, or endocrine diseases. The diagnosis of TINU is mainly based on clinical and analytical findings, and although urinary β2-microglobulin is a useful parameter no specific diagnostic test is available. Current perspectives intend to facilitate its diagnosis identifying susceptibility HLA genotypes, serologic markers and imaging tools to avoid renal biopsy. Treatment options for TINU syndrome include corticosteroids, immunosuppressive agents, and intravenous immunoglobulins, but relapses are frequent, and management can be challenging. The purpose of this review is to provide an updated summary of the diagnostic and treatment strategies of TINU syndrome, helping clinicians recognize and manage this rare autoimmune disorder.

Tubulointerstitial nephritis and uveitis in children during the COVID-19 pandemic: report of four cases

Tubulointerstitial nephritis and uveitis (TINU) is a rare autoimmune disorder often triggered by drugs and infections. Since the onset of the COVID-19 pandemic, we have observed an unusual cluster of paediatric cases. Four children (3 females) were diagnosed with TINU (median age 13 years) following a kidney biopsy and ophthalmologic assessment. Presenting symptoms included abdominal pain (3 cases), fatigue, weight loss and vomiting (2 cases). At presentation, median eGFR was 50.3 ml/min/1.73m2 (range 19.2-69.3). Anaemia was common (3 cases) with median haemoglobin of 10.45 g/dL (range 8.4-12.1). Two patients were hypokalaemic and 3 had non-hyperglycaemic glycosuria. Median urine protein:creatinine ratio was 117 mg/mmol (range 68-167). SARS-CoV-2 antibodies were detected in 3 cases at presentation. All were asymptomatic for COVID-19 with a negative PCR. Kidney function improved following high-dose steroids. However, disease relapse was observed during steroid tapering (2 cases) and upon discontinuation (2 cases). All patients responded well to further high dose steroids. Mycophenolate mofetil was introduced as a steroid-sparing agent. At latest follow up (range 11-16 months), median eGFR was 109.8 ml/min/1.73m2. All four patients continue on mycophenolate mofetil, with 2 patients applying topical steroids for uveitis. Our data suggest that SARS-CoV-2 infection might be a trigger for TINU.

Renal outcomes in tubulointerstitial nephritis and uveitis (TINU) syndrome: a systematic review and meta-analysis

BACKGROUND

Tubulointerstitial nephritis and uveitis syndrome (TINU) is a rare condition characterised by bilateral uveitis and interstitial nephritis. There is no nationally, or internationally agreed upon treatment regimen. A systematic review was undertaken to report the renal outcomes in TINU, and treatments used.

METHODS

Medline (1969-2021) and EMBASE (1988-2021) databases were searched for primary studies, clinical practice guidelines and case reports of adult and paediatric TINU cases, as defined by Mandeville criteria. Two reviewers identified articles meeting inclusion criteria (registered with PROSPERO). Data were extracted into a synthesis table and meta-analysis performed. Quality of case series was also assessed.

RESULTS

One hundred twenty-two articles were identified, totalling 257 cases included in the meta-analysis. Females were more commonly affected than males (2:1), and median age was 19 years. GFR at follow-up correlated with nadir GFR, and the proportion with GFR <90 ml/min/1.73 m² was statistically different between adult and paediatric groups. Of the entire cohort, 40% had GFR <90 ml/min/1.73 m² at follow-up. Glucocorticoid monotherapy was the most common treatment (70%); other strategies included no treatment (9%) and immunosuppressant drugs (e.g. azathioprine), mostly in steroid-resistant cases, or as 'steroid-sparing' alternatives.

CONCLUSIONS

The majority of literature regarding TINU is limited to case reports and case series. There are no prospective trials assessing the effects of different treatments on renal outcomes, and currently employed treatment strategies are physician-specific without a reliable evidence-base. Prospective data collection as part of multicentre trials should be a research focus to improve the evidence-base.

A case of tubulointerstitial nephritis and uveitis syndrome following drug‐induced acute interstitial nephritis

Distinguishing between late‐onset TINU syndrome and drug‐induced AIN remains difficult given that patients with TINU syndrome may develop uveitis long after the onset of AIN. Therefore, ophthalmic examination is required not only upon diagnosis but also continuously or when eye symptoms and relapse of urinary findings are observed.

Tubulointerstitial nephritis and uveitis syndrome: a systematic review

BACKGROUND

Tubulointerstitial nephritis and uveitis (TINU) syndrome is defined as the occurrence of tubulointerstitial nephritis (TIN) and uveitis in the absence of other systemic diseases. The most comprehensive review on this condition was published in 2001.

METHODS

We conducted a systematic review of the literature for cases of TINU syndrome. MEDLINE and Embase databases were screened. Full-length articles or letters reporting cases with both TIN and uveitis were selected. We investigated differences between males and females and paediatric and adult cases. Multivariate analysis was performed to identify potential risk factors for chronic kidney disease (CKD) development.

RESULTS

A total of 233 articles reporting 592 TINU cases were retained for the analysis. The median age of the included subjects was 17 years (interquartile range 13-46) with a female predominance (65%). Uveitis most frequently (52%) followed renal disease and was mostly anterior (65%) and bilateral (88%). Children tended to have more ocular relapses, while they were slightly less likely than adults to suffer from acute kidney injury and to develop CKD. Adult age as well as posterior or panuveitis were associated with an increased risk of developing CKD.

CONCLUSIONS

TINU affects both children and adults, with some differences between these two categories. Adult age and the presence of a posterior uveitis or panuveitis appear to be associated with the development of CKD.

Aetiology, course and treatment of acute tubulointerstitial nephritis in paediatric patients: a cross-sectional web-based survey

BACKGROUND

Acute tubulointerstitial nephritis (TIN) is a significant cause of acute renal failure in paediatric and adult patients. There are no large paediatric series focusing on the aetiology, treatment and courses of acute TIN.

PATIENTS, DESIGN AND SETTING

We collected retrospective clinical data from paediatric patients with acute biopsy-proven TIN by means of an online survey. Members of four professional societies were invited to participate.

RESULTS

Thirty-nine physicians from 18 countries responded. 171 patients with acute TIN were included (54% female, median age 12 years). The most frequent causes were tubulointerstitial nephritis and uveitis syndrome in 31% and drug-induced TIN in 30% (the majority of these caused by non-steroidal anti-inflammatory drugs). In 28% of patients, no initiating noxae were identified (idiopathic TIN). Median estimated glomerular filtration rate (eGFR) rose significantly from 31 at time of renal biopsy to 86 mL/min/1.73 m² 3-6 months later (p<0.001). After 3-6 months, eGFR normalised in 41% of patients (eGFR ≥90 mL/min/1.73 m²), with only 3% having severe or end-stage impairment of renal function (<30 mL/min/1.73 m²). 80% of patients received corticosteroid therapy. Median eGFR after 3-6 months did not differ between steroid-treated and steroid-untreated patients. Other immunosuppressants were used in 18% (n=31) of patients, 21 of whom received mycophenolate mofetil.

CONCLUSIONS

Despite different aetiologies, acute paediatric TIN had a favourable outcome overall with 88% of patients showing no or mild impairment of eGFR after 3-6 months. Prospective randomised controlled trials are needed to evaluate the efficacy of glucocorticoid treatment in paediatric patients with acute TIN.

Long-term outcome of biopsy-proven idiopathic tubulointersitial nephritis with or without uveitis in children-a nationwide follow-up study

BACKGROUND

Only a few studies reporting the long-term outcome of children with idiopathic tubulointerstitial nephritis (TIN) and uveitis syndrome (TINU) are available. We studied the long-term kidney and ocular outcome in a nationwide cohort of children with TIN or TINU.

METHODS

All patients followed up for a minimum of 1 year by a paediatrician and an ophthalmologist were enrolled. The data on plasma creatinine (P-Cr), estimated glomerular filtration rate (eGFR), proteinuria, hypertension and uveitis were collected retrospectively.

RESULTS

Fifty-two patients were studied. Median age at time of diagnosis was 13.1 (1.8-16.9) years and median follow-up time was 5.7 (1.1-21.2) years. Forty-five (87%) patients were initially treated with glucocorticoids. The median of the maximum P-Cr was 162 μmol/l (47-1,016) and that of eGFR 47 ml/min/1.73m² (8-124). Uveitis was diagnosed in 33 patients (63%) and 21 (40%) patients developed chronic uveitis. P-Cr normalised in a median of 2 months. Eleven (21%) patients had nephritis recurrence during or after discontinuation of glucocorticoids. At the latest follow-up, 13 (25%) patients had eGFR < 90 ml/min/1.73m² (median 83; 61-89 ml/min/1.73m²). Six patients had tubular proteinuria; all presented with TIN without uveitis. Seven (13%) patients were hypertensive. Eleven (21%) patients had uveitis. One patient developed uraemia and was later transplanted.

CONCLUSIONS

Our study questions the previously reported good long-term kidney and ocular outcome of patients with TIN/TINU. Decreased kidney function and/or ocular co-morbidities may persist for several years; thus, both kidney and ocular follow-up for at least 1 year is warranted. A higher resolution version of the Graphical abstract is available as Supplementary information.

Tubulointerstitial nephritis and uveitis (TINU) syndrome: a review

Inflammation of renal interstitium and uveal tissue establishes the two components of tubulointerstitial nephritis and uveitis (TINU) syndrome. Although believed to occur more frequently in young females, a broad spectrum of patients can be affected. Both renal and eye disease can be asymptomatic and may not manifest simultaneously, having independent progressions. Renal disease manifests as acute kidney injury and may cause permanent renal impairment. Eye inflammation can manifest in different anatomical forms, most commonly as bilateral anterior uveitis and may progress to a chronic course. TINU syndrome accounts for approximately 1%–2% of uveitis in tertiary referral centres. A literature review covering the clinical features, pathogenesis, diagnosis and treatment is presented.

Tubulointerstitial Nephritis

Tubulointerstitial nephritis (TIN) is a cause of acute kidney injury in children characterized histologically by an inflammatory cell infiltrate in the kidney interstitium. The most common causes of TIN in children include medications, infections, inflammatory disorders, and genetic conditions. TIN typically presents with nonoliguric acute kidney injury and may be associated with systemic symptoms, including fever, rash, and eosinophilia. The long-term prognosis is generally favorable, with full kidney recovery; however, some patients may develop progressive chronic kidney disease. Immunosuppressive therapy may be indicated for severe or prolonged disease.

Measurement of urinary biomarkers in a case of tubulointerstitial nephritis and uveitis syndrome during glucocorticoid treatment

Tubulointerstitial nephritis and uveitis (TINU) is a rare syndrome in which idiopathic interstitial nephritis coexists with chronic recurrent uveitis. This syndrome often represents systemic disorders such as arthralgia, rash, prolonged fever, anaemia and ocular symptoms that require medication including glucocorticoid administration. Recently, novel urinary biomarkers, such as kidney injury molecule-1, neutrophil gelatinase-associated lipocalin and liver-type fatty acid-binding protein, were shown to be associated with tubulointerstitial damage and were elevated in interstitial nephritis. We evaluated these urinary biomarkers in a case of TINU syndrome before and during treatment and found that their levels were elevated at onset and decreased during treatment, especially NGAL. We conclude that these urinary biomarkers are useful to evaluate and predict prognosis in interstitial nephritis.

The Syndrome of Tubulointerstitial Nephritis With Uveitis (TINU)

The syndrome of tubulointerstitial nephritis and uveitis (TINU) is a multisystemic autoimmune disorder that may occur in response to various environmental triggers, including drugs and microbial pathogens. Evidence exists of HLA antigen-related genetic predisposition to developing TINU. The resulting inflammation affects chiefly the ocular uvea and renal tubules, although other organs may be involved. TINU is uncommon; only about 200 cases are on record since its original description 40 years ago, although it is possible that new ones are no longer being reported. Although its incidence is highest in children and adolescents, all ages may be affected. Renal and ocular inflammation may be clinically severe and persistent, but the prognosis for the majority of patients with TINU is favorable. Owing to its low prevalence, no standard therapeutic protocols have been established, but most reported cases have been treated with corticosteroids or other immunomodulatory agents. TINU has many features in common with sarcoidosis, the main clinical entity from which it must be distinguished. This article begins with an illustrative case vignette, followed by an overview of the syndrome and current theories regarding its pathogenesis.

Tubulointerstitial nephritis and uveitis

PURPOSE OF REVIEW

Tubulointerstitial nephritis and uveitis (TINU) is an important yet underrecognized ocular inflammatory syndrome. This review summarizes key historical publications that identified and defined the syndrome, and more recent literature that reveal the importance of urinary β2-microglobulin testing and kidney biopsy in the diagnostic evaluation of patients with TINU. Additionally, research studies providing new insights into disease pathogenesis are highlighted.

RECENT FINDINGS

In contrast with initial reports of TINU manifesting exclusively as an anterior uveitis in pediatric patients, more recent reports have identified TINU in patients of all ages with a wide range of ocular manifestations. Urinary β2-microglobulin has emerged as a sensitive and specific laboratory screening test, and the role of kidney biopsy in differentiating TINU from sarcoidosis continues to evolve. Genetic studies have identified HLA-DQA101, HLA-DQB105, and HLA-DRB101 as high-risk alleles and the identification of antimonomeric C-reactive protein antibodies suggests a role for humoral immunity in disease pathogenesis. Management strategies have evolved to include systemic anti-inflammatory treatment as a result of important outcome studies in patients with significant renal and ocular disease.

SUMMARY

With greater recognition, understanding, and treatment of this syndrome, both ocular inflammation and renal disease can be better addressed.

Successful treatment of tubulointerstitial nephritis and uveitis with steroid and azathioprine in a 12-year-old boy

Tubulointerstitial nephritis and uveitis (TINU) syndrome is a rare disease, often underdiagnosed or misdiagnosed in children. We describe the case of a 12-year-old boy who presented to Severance Hospital with a 1-month history of bilateral conjunctival injection. He was first evaluated by an Ophthalmologist in another hospital and diagnosed with panuveitis. Laboratory tests indicated renal failure, and a renal biopsy confirmed the diagnosis of acute tubulointerstitial nephritis. An extensive exclusion of all possible causes allowed a diagnosis of TINU syndrome. The patient was treated with a systemic corticosteroid (initially prednisolone, 2 mg/kg and later deflazacort 1 mg/kg) and topical steroid drops for 1 month. Azathioprine was later added to the treatment regimen and the systemic steroid was slowly tapered. The final outcome of renal-ocular disease was favorable in the patient. However, long-term follow-up is necessary to properly manage frequent relapses and incomplete renal recovery. TINU should be considered as a differential diagnosis in children with uveitis or acute renal failure.

Tubulointerstitial Nephritis and Uveitis Syndrome: Are Drugs Offenders or Bystanders?

A 16-year-old female patient was admitted to our hospital due to progressive renal dysfunction with an increased serum creatinine (sCr) level of 1.7 mg/dL. Her clinical course without any ocular manifestations and results of drug-induced, lymphocyte-stimulating tests, in addition to a renal histological assessment, initially encouraged us to ascribe the patient’s renal abnormalities to drug-induced acute interstitial nephritis (AIN). Four months later, she started to complain about reduced visual acuity when she was found to have anterior bilateral uveitis despite the recovered renal function with almost constant sCr levels around 0.7 mg/dL. Thus, a diagnosis of tubulointerstitial nephritis and uveitis (TINU) syndrome was finally made. Our case illustrates the difficulties in distinguishing late-onset uveitis TINU syndrome from drug-induced AIN at the time of the renal biopsy, thereby suggesting the importance of a longitudinal follow-up to overcome the potential underdiagnosis of the disease. Several diagnostic conundrums that emerged in this case are also discussed.

Cytokine dynamics in a 14-year-old girl with tubulointerstitial nephritis and uveitis syndrome

Tubulointerstitial nephritis and uveitis (TINU) syndrome, which was first described in 1975, has been reported in more than 130 patients, mostly in adolescent or young women. Although data concerning the etiologic background of this inflammatory disease are limited, several humoral factors, including cytokines, have been reported in association with the disease. Here, we report a case of TINU in a 14-year-old girl, whose renal and ophthalmological improvement was associated with the decrease of serum levels of tumor necrosis factor-α (TNF-α), interferon-γ (IFN-γ), and interleukin-8 (IL-8). This suggests the presence of T-cell-mediated immunity in this unique syndrome.

HLA-DR, DQ class II DNA typing in pediatric panuveitis and tubulointerstitial nephritis and uveitis

PURPOSE

To describe chorioretinal lesions in pediatric uveitis that are associated strongly with the HLA-DR, DQ class II type associated with tubulointerstitial nephritis and uveitis (TINU).

DESIGN

Retrospective, observational case series.

METHODS

SETTING

University-based clinic.

PATIENT POPULATION

Fifteen consecutive patients with onset of bilateral panuveitis at less than 16 years of age who were seen between September 2004 and October 2012 and 6 pediatric patients with confirmed TINU.

OBSERVATION PROCEDURE

HLA-DR, DQ class II DNA typing.

MAIN OUTCOME MEASURE

Detection of the HLA-DRB1*01 and HLA-DQB1*05 risk alleles for TINU.

RESULTS

Fourteen (93%) of the 15 patients with otherwise unexplained pediatric panuveitis typed HLA-DRB1*01-HLA-DQB1*05. Eleven (73.3%) of 15 patients had bilateral sharply demarcated, usually inferior, 200- to 300-μm spots of chorioretinal atrophy, and 4 (27.7%) of 15 patients had bilateral clusters of 500- to 750-μm poorly defined orange choroidal lesions without overlying atrophy of the retinal pigment epithelium. None had interstitial nephritis. Four of the 6 definite TINU cases had class II typing and TINU risk alleles; all 6 had bilateral panuveitis. The frequency of risk alleles was statistically higher in those with pediatric panuveitis than in the North American population and in nonpanuveitis pediatric uveitis patients assumed to have the North American HLA distribution (P < .0001, Fischer exact test). Positive likelihood ratios were 9.92 to 5.18, depending on assumptions regarding pretest probability of disease.

CONCLUSIONS

Recognition of characteristic chorioretinal lesions in otherwise unexplained pediatric panuveitis, supported by selective HLA class II DNA typing, is useful in narrowing diagnostic possibilities and directing further evaluations. Panuveitis is underappreciated as a manifestation of TINU.

Prednisone in the treatment of tubulointerstitial nephritis in children

BACKGROUND

Patients with tubulointerstitial nephritis (TIN) may develop permanent renal impairment. However, there are no prospective studies available on the treatment of TIN.

METHODS

The effect of prednisone in the treatment of TIN was evaluated in a total of 17 patients who received prednisone or who were followed up without medication. The patient group was subdivided based on the initial plasma creatinine (PCr), below or above 150 μmol/l.

RESULTS

All prednisone-treated patients had normal plasma creatinine (PCr) after 1 month of treatment (median 59.1 [45-85] μmol/l) whereas only 50 % of patients in the non-treatment group had normal creatinine (median 81.0 [42-123] μmol/l) at the same time point (p = 0.025). During 6 months' follow-up, PCr decreased in all patient groups; however, it decreased significantly only in prednisone-treated patients with baseline PCr >150 μmol/l (p < 0.001). At the end of follow-up, no difference in PCr, glomerular filtration rate (GFR), or low molecular weight (LMW) proteinuria could be found between the study groups. A considerable number of patients in both groups had subnormal GFR and/or persistent LMW proteinuria at the 6-month follow-up visit. Eighty-two percent of the patients had uveitis.

CONCLUSIONS

Prednisone speeds up the recovery from renal symptoms of TIN, especially in patients with severe nephritis. The renal function did not differ significantly between prednisone and control patients after 6 months' follow-up.

Tubulo-interstitial nephritis and uveitis syndrome in a 6-year-old boy: case report

A 6-year-old boy presented with a 4-month history of anorexia, weight loss and fatigue and was found to have tubulo-interstitial nephritis and uveitis (TINU) syndrome. After 2 months of corticosteroid therapy, resolution of the uveitis was almost complete but renal function showed only partial improvement. He was still in renal failure 6 months after diagnosis, but there was no relapse of the uveitis. Although the prognosis of TINU in children and adults is reported to be excellent, the outcome in young children can be less favourable, probably owing to delayed diagnosis and initiation of treatment.

HLA associations with tubulointerstitial nephritis with or without uveitis in Finnish pediatric population: a nation-wide study

The human leukocyte antigen (HLA) genotype has been shown to associate with tubulointerstitial nephritis (TIN) and tubulointerstitial nephritis with uveitis syndrome (TINU). The association of HLA genes with TIN was examined in this nation-wide study. HLA genotyping was performed in 31 pediatric patients with biopsy-proven TIN. All patients were examined by an ophthalmologist to diagnose possible uveitis. Class II HLA genotypes of TIN patients were compared with the Finnish reference population. We found a significant association between the HLA alleles DQA1*04:01 [risk ratio (RR) 5.0, 95% confidence interval (CI) 2.0-11.2], DQB1*04:02 (RR 2.7, 95% CI 1.4-5.3), and DRB1*08 (RR 3.8, 95% CI 1.5-8.4) and TIN. Uveitis was found in 20/31 (64.5%) patients. HLA genotyping of the TINU patients showed additional risk HLA alleles: DQA1*01:04 (RR 6.1, 95% CI 1.5-17.8), and DRB1*14 (RR 8.2, 95% CI 2.2-22.1). The alleles DQA1*01:04 (RR 8.8, 95% CI 2.2-26.5), DQA1*04:01 (RR 3.2, 95% CI 1.2-7.3), and DRB1*14 (RR 12.0, 95% CI 3.2-33.0) were more frequent in patients with TIN and chronic uveitis than in reference population. The HLA class II haplotype DQA1*04:01/DQB1:04:02/DRB1*08 was the most common combination in our study population (58.1%). None of the patients had haplotype DQA1*04:01/DQB1*06:02/DRB1*15, which is common in Finland. HLA genotype did not predict the renal outcome. We found a strong association between certain HLA genotypes both in TIN and TINU patients. The TIN/TINU-associated HLA alleles appear to vary depending on study population.

Tubulointerstitial nephritis and uveitis syndrome in a twelve-year-old girl

Tubulointerstitial nephritis and uveitis (TINU) syndrome is a rare disorder defined by the combination of biochemical abnormalities, tubulointerstitial nephritis, and uveitis. We describe a 12-year-old female, presented with a ten-day history of fever, characterized by sudden onset and rapid spontaneous resolution in few hours, accompanied by shivering, extreme fatigue, and loss of appetite. Laboratory values were consistent with renal failure of tubular origin. Renal biopsy confirmed a tubulointerstitial nephritis, with acute tubulitis, polymorphonuclear infiltration, and microabscesses. The renal interstitium was occupied by a dense inflammatory infiltrate, consisting of lymphocytes, plasma cells, and neutrophils. Glomerular structures were preserved. Ophthalmological examination that suggested a previous asymptomatic bilateral uveitis and HLA typing (HLA-DQA1∗0101/0201 and HLA-DQB1∗0303/0503) further supported the suspect of TINU syndrome. TINU syndrome is probably an underdiagnosed disorder, responsible for many cases of idiopathic anterior uveitis in young patients, especially in those who have asymptomatic renal disease and when proper diagnostic tests are not performed at the time of presentation.

A rare case of acute renal failure due to tubulointerstitial nephritis and uveitis syndrome successfully treated with steroid

We hereby describe a 49-year-old woman with acute renal failure due to tubulointerstitial nephritis and uveitis (TINU) syndrome. This patient presented with vomiting and nausea and was found to have chronic uveitis, elevated creatinine, and interstitial nephritis. The combination of tubulointerstitial nephritis and uveitis emerged the diagnosis of TINU syndrome after a stepwise examination for differential diagnosis. Clinical course and renal function improved quickly on oral steroids but not to normal range. TINU syndrome, although known to some ophthalmologists and nephrologists, is still rather obscure. TINU syndrome should be considered in patients with uveitis in combination with acute renal failure. The prognosis for the renal disorder is excellent, although the uveitis often recurs or remains chronic.

Tubulointerstitial nephritis and uveitis syndrome in children: a prospective multicenter study

PURPOSE

To evaluate the occurrence and characteristics of uveitis related to tubulointerstitial nephritis (TIN) in children.

DESIGN

Prospective, observational, multicenter, partly placebo-controlled treatment trial.

PARTICIPANTS

Nineteen children with a biopsy-proven TIN.

METHODS

Patients were treated with prednisone or followed without treatment. In addition to the nephrologic evaluations, the prospective follow-up included structured ophthalmological examinations at the onset of TIN and at 3 and 6 months after the diagnosis.

MAIN OUTCOME MEASURES

Occurrence, clinical features, and outcome of uveitis.

RESULTS

Some 84% (16/19) of the patients had uveitis, 83% (5/6) in the nontreatment group and 82% (9/11) in the prednisone-treated group. The remaining 2 patients, originally in the nontreatment group, were switched to the prednisone group after 2 weeks. Both of them developed uveitis. Altogether, 3 patients developed uveitis during prednisone treatment and 2 patients showed worsening of uveitis despite the systemic corticosteroid. Some 50% (8/16) of the patients with uveitis presented with no ocular symptoms; 88% (14/16) of the patients had a chronic course of uveitis. Two patients were diagnosed with uveitis before nephritis; nephritis and uveitis were diagnosed within 1 week from each other in 7 patients, and uveitis developed 1 to 6 months after the diagnosis of TIN in 7 patients.

CONCLUSIONS

There was no statistically significant difference in the occurrence of uveitis in patients with TIN in the prednisone and nontreatment groups. In this study, the occurrence of uveitis associated with TIN was considerably higher than previously reported. Uveitis related to TIN may develop late and is often asymptomatic. The ophthalmological follow-up of all patients with TIN is warranted for at least 12 months starting with 3-month intervals.

FINANCIAL DISCLOSURE(S)

The authors have no proprietary or commercial interest in any material discussed in this article.

A case of tubulointerstitial nephritis and uveitis syndrome in an elderly patient

Tubulointerstitial nephritis and uveitis (TINU) syndrome is a rare disease entity usually occurring in children. In the present study a case of TINU syndrome in an elderly patient is described and relevant literature is reviewed. A 61-year-old man presented with bilateral flank pain, urinary frequency, and foamy urine. A kidney ultrasonography revealed an increase in kidney parenchyma echogenicity. Following a kidney biopsy, the patient was diagnosed with acute tubulointerstitial nephritis. An ophthalmology examination initially performed for floater symptoms, revealed anterior uveitis in both eyes. Acute tubulointerstitial nephritis and anterior uveitis in both eyes responded to treatment with oral prednisolone, furosemide, carvedilol, and a topical steroid. TINU syndrome can occur in the elderly and should be part of the differential diagnosis when seeing a patient who has uveitis in association with renal disease; any therapy should be managed by both an internist and an ophthalmologist.

Acute tubulointerstitial nephritis

Acute tubulointerstitial nephritis (TIN) is a frequent cause of acute renal failure, characterised by the presence of inflammatory cell infiltrate in the interstitium of the kidney. Immuno-allergic reaction to certain medications, mainly non-steroidal anti-inflammatory drugs and antibiotics are by far the most important etiology for TIN today, but other situations such as infections, toxins, and vasculitis are known to induce TIN. Incidence of TIN is increasing, probably due to prescription habits and NSAID overuse, representing 3-7% of acute kidney injury in biopsies in children. Avoidance of the causal substance and rapid steroid therapy are hallmarks for patient care, but spontaneous initial recovery is very frequent and the general prognosis seems satisfactory. However, development of chronic TIN, without response to steroid or other immunosuppressive treatment, is possible. As the largest part of TIN is secondary to certain drugs, clear indications in particular for NSAID or antibiotics should be respected to reduce the number of TIN cases.

Recurrent tubulointerstitial nephritis and uveitis syndrome in a renal transplant recipient

We report for the time a patient with recurrence of tubulointerstitial nephritis and uveitis (TINU) following renal transplantation. Our patient was diagnosed at the age of 8 years and, despite treatment with systemic steroids, developed established renal failure. At the age of 17 years, he underwent a live-related donor renal transplant. Immunosuppression included tacrolimus, mycophenolate mofetil and prednisolone. Having had normal renal function for 3 years after transplantation, he developed uveitis and decline in the graft function. A biopsy of the allograft demonstrated recurrent granulomatous interstitial nephritis. The recurrence of TINU following transplantation suggests a role for circulating autoantibodies in the disease pathology.

Clinical outcome and occurrence of uveitis in children with idiopathic tubulointerstitial nephritis

Acute idiopathic tubulointerstitial nephritis (TIN) is considered a condition with a good long-term prognosis. However, there is evidence that some patients develop permanent renal impairment. The aim of this study was to evaluate the clinical characteristics of TIN at the time of diagnosis in children and determine whether the findings upon presentation predict renal outcome. The clinical data and biopsy findings from 26 children with idiopathic TIN admitted to four Finnish university hospitals were analyzed retrospectively. Twenty-five patients (96%) manifested renal insufficiency. After the mean follow-up time of 2.75 years (SD 2.5; 0.9-13.5), 4 patients (15%) had permanent renal insufficiency and 8 patients (31%) had persistent low-molecular weight proteinuria. Uveitis was found in 12 patients (46%). Four of these patients (33%) developed chronic uveitis. Our analysis showed that none of the laboratory or biopsy findings upon presentation prognosticated renal outcome. No correlation between renal disease and uveitis could be found either. The occurrence of uveitis among TIN patients was higher than previously reported. Uveitis may develop late and without recurrence of renal dysfunction. Therefore, follow-up by a pediatrician and by an ophthalmologist is warranted in children with acute TIN for at least 12 months from diagnosis.

Tubulointerstitial Nephritis and Uveitis (TINU) Syndrome in a 52-Year-Old Female: A Case Report and Review of the Literature

Tubulointerstitial nephritis and uveitis (TINU) syndrome is a rare entity first described in 1975, affecting mainly young women and adolescents. We present a case of a 52-year-old female patient (one of the oldest in the literature) who complained of fever, anorexia, nausea, and vomiting. After she was admitted to our hospital, laboratory tests revealed tubular proteinuria, elevated erythrocyte sedimentation rate (ESR), anemia, and renal insufficiency (serum creatinine 4.2 mg/dL) with metabolic acidosis. Ophthalmologic examination revealed anterior uveitis (iritis) and renal biopsy showed acute tubulointerstitial nephritis. The diagnosis of TINU syndrome was established and the patient was treated with oral corticosteroids. All symptoms and ophthalmologic abnormalities disappeared after 6 weeks of treatment. Renal function also recovered completely and remained stable at follow-up. TINU syndrome should be considered in the differential diagnosis of unexplained tubulointerstitial nephritis, especially in the presence of ocular findings. Corticosteroid therapy is still controversial, but it helps in the quick resolution of renal and mainly eye abnormalities.

Serial renal biopsies in three girls with tubulointerstitial nephritis and uveitis syndrome

Tubulointerstitial nephritis and uveitis (TINU) syndrome is considered to have a good prognosis even without any immunosuppressive therapy, although there is no histological evidence to support this. The objective of this study was to evaluate, retrospectively, serial renal biopsy findings in three girls with TINU syndrome who were treated with prednisolone. At presentation, all patients had significantly elevated urinary beta(2)-microglobulin levels (7583-19,313 microg/l) and high serum creatinine levels (0.93-1.3 mg/dl). The elevated beta(2)-MG and creatinine levels persisted for 1 month, and renal biopsies were performed to establish a definitive diagnosis. The initial biopsy specimens of all patients revealed marked interstitial enlargement consisting of infiltration of lymphocytes; there was also notable tubulitis and infiltration of eosinophils. All patients received prednisolone therapy following the diagnosis. A second renal biopsy was performed 9 months after the first biopsy for two of three patients, and 2 years later for the third patient. The biopsy specimens taken at 9 months still showed histological changes of acute inflammation; in contrast, that taken at 2 years showed a lower degree of acute inflammation, but scar formation was observed in some regions. Based on these results, we conclude that selected TINU syndrome patients require some immunosuppressive therapy.

Acute kidney injury in children

Acute kidney injury (AKI) (previously called acute renal failure) is characterized by a reversible increase in the blood concentration of creatinine and nitrogenous waste products and by the inability of the kidney to regulate fluid and electrolyte homeostasis appropriately. The incidence of AKI in children appears to be increasing, and the etiology of AKI over the past decades has shifted from primary renal disease to multifactorial causes, particularly in hospitalized children. Genetic factors may predispose some children to AKI. Renal injury can be divided into pre-renal failure, intrinsic renal disease including vascular insults, and obstructive uropathies. The pathophysiology of hypoxia/ischemia-induced AKI is not well understood, but significant progress in elucidating the cellular, biochemical and molecular events has been made over the past several years. The history, physical examination, and laboratory studies, including urinalysis and radiographic studies, can establish the likely cause(s) of AKI. Many interventions such as 'renal-dose dopamine' and diuretic therapy have been shown not to alter the course of AKI. The prognosis of AKI is highly dependent on the underlying etiology of the AKI. Children who have suffered AKI from any cause are at risk for late development of kidney disease several years after the initial insult. Therapeutic interventions in AKI have been largely disappointing, likely due to the complex nature of the pathophysiology of AKI, the fact that the serum creatinine concentration is an insensitive measure of kidney function, and because of co-morbid factors in treated patients. Improved understanding of the pathophysiology of AKI, early biomarkers of AKI, and better classification of AKI are needed for the development of successful therapeutic strategies for the treatment of AKI.

A Case of Tubulointerstitial Nephritis and Uveitis (TINU) Syndrome with High ASLO Titer

Tubulointerstitial nephritis and uveitis (TINU) syndrome is a rare autoimmune disease and the pathogenesis is still unknown. We report a case of TINU syndrome with high ASLO titer.

Uveitis improved and urine β₂-MG normalized with low dose systemic predonisolone and cyclosporin A. The high ASLO titer in early phase suggested that streptococcal infection might have triggered TINU syndrome. Lymphocyte phenotypes normalized after treatment with low dose systemic predonisolone and cyclosporin A.

Tubulointerstitial nephritis and uveitis syndrome in a mother and her son

A mother and her son, both with tubulointerstitial nephritis and uveitis syndrome (TINU) are reported. The nephritis presented itself at 13 years in the mother and at 10 years in her son. Glomerular filtration (GFR) decreased in both, and renal biopsies confirmed the diagnosis. Nephritis preceded the onset of uveitis in both. Clinical course and renal function improved quickly on oral steroids in the boy. The mother's hyperazotemia decreased spontaneously (without steroids), but not to normal range, and remained stable for 35 years of follow-up. Local steroids due to recurrences of uveitis were repeatedly needed in both. We believe this is the first report on familial occurrence of inherited TINU syndrome in two generations.

A case of tubulointerstitial nephritis and uveitis syndrome with severe immunologic dysregulation

Idiopathic tubulointerstitial nephritis and uveitis (TINU) syndrome is an uncommon condition, characterized by acute tubulointerstitial nephritis (TIN) with a favorable course and uveitis with a chronic relapsing course. The pathogenesis remains unclear, but a lymphocyte-mediated immune mechanism has been suggested. A 9-year-old boy was evaluated for fatigue and 2 kg of weight loss. Renal glucosuria, elevated urine beta(2)-microglobulin (MG), progressive renal dysfunction, polyclonal hypergammaglobulinemia, various autoantibodies and abnormal lymphocyte phenotypes were found. A renal biopsy revealed acute TIN. After 2 months of treatment with prednisolone, renal function and polyclonal hypergammaglobulinemia were normalized. While tapering prednisolone, anterior uveitis developed, which was improved with topical steroid. But abnormal lymphocyte phenotypes and autoantibodies persisted on low-dose prednisolone. Uveitis became aggravated, and urine beta(2)-MG increased again. The second renal biopsy (7 months later) was normal except for minimal focal interstitial fibrosis. Uveitis was not responsive to systemic steroids, but improved with additional cyclosporin. Abnormal lymphocyte phenotypes improved, and most autoantibodies disappeared. We report a rare case of idiopathic TINU syndrome with severe immunologic dysregulation, which correlated with the clinicopathological and biochemical parameters. The information about lymphocyte phenotypes and autoantibodies may provide more insight into the pathophysiology and the clinical course of uveitis in this rare disorder.

Adult onset tubulointerstitial nephritis and uveitis syndrome

A Turkish woman aged 44 years who presented with a 1 month history of abdominal pain, fatigue and weight loss of 10 kg was diagnosed as having acute tubulointerstitial nephritis. Opthalmological evaluation revealed unilateral uveitis and contralateral chorioretinal scarring. X-ray films of the pelvis revealed unilateral sacroileitis. An elevated erythrocyte sedimentation rate, C-reactive protein, tubular proteinuria and renal glucosuria returned to normal 2 weeks after treatment was started. It is important to be aware of tubulointerstitial nephritis and uveitis syndrome in order to achieve a quick diagnosis in patients with renal impairment and tubular dysfunction with minor symptoms so that appropriate management can be started early.

A Case of Tubulointerstitial Nephritis and Uveitis in an Adult Male

We report a case of tubulointerstitial nephritis and uveitis (TINU) syndrome in an adult male. A 40-year-old man was found to have bilateral anterior uveitis and mild renal insufficiency with high urinary beta-2 microglobulin. Work up for connective tissue and infectious diseases were negative. His kidney function normalized spontaneously and remained normal at 1 year without intervention. Uveitis responded completely to local corticosteroid treatment and has not recurred.

Tubulointerstitial nephritis and uveitis in monozygotic twin boys

We describe monozygotic male twins who developed tubulointerstitial nephritis and uveitis (TINU) almost 2 years apart. They presented with non-specific symptoms and were noted to have glycosuria and renal impairment. Both children have uveitis. One had biopsy-proven interstitial nephritis and the other had biochemical evidence of transient tubular dysfunction. While the renal parameters improved, they are still under treatment for uveitis. The occurrence of TINU in identical twins at an interval of just under 2 years supports a strong genetic element in the aetiology of this syndrome. We believe this is the first report of male twins with TINU.

Tubulointerstitial Nephritis With Uveitis (TINU): A Syndrome Rheumatologists Should Recognize

Patients with uveitis such as the patient whose case is reported here are often referred to rheumatologists for investigation of possible underlying systemic diseases. This patient presented with decreased vision, photophobia, weight loss, and fevers and was found to have uveitis, elevated creatinine, and interstitial nephritis. This raised consideration of a variety of systemic diseases before she was determined to have the tubulointerstitial nephritis with uveitis (TINU) syndrome. The TINU syndrome, although known to some ophthalmologists and nephrologists, is still rather obscure. Uncommon but not rare with 133 cases in the literature, TINU syndrome should be one more diagnosis to be considered in patients with uveitis. The median age of onset is 15, but it ranges from 9 to 74. There is a 3:1 female preponderance. Response to corticosteroids, which are used in 80% of reported cases, is rapid. The prognosis for the renal disorder is excellent, although the uveitis often recurs or remains chronic.

Repeat renal biopsy in children with severe idiopathic tubulointerstitial nephritis

Idiopathic (primary) tubulointerstitial nephritis (TIN) of childhood is relatively rare. Four children, two with concomitant uveitis, aged 8-14 years, with idiopathic TIN who underwent repeat renal biopsy were retrospectively evaluated. At presentation, all had a significant elevation of the urinary beta(2)-microglobulin/creatinine ratio (beta2MG ratio), ranging from 10100 to 44550, with increased histological indices of tubulointerstitial scores (TI scores) in excess of 6 points. Three of the children received prednisolone (PSL) therapy following diagnosis, while the remaining child received the therapy 30 months after the first renal biopsy. In the children that received prompt PSL therapy, a rapid decrease in urinary beta2MG ratio was observed and the TI scores obtained at a mean interval of 16 months after the first biopsy decreased to less than 5, while preserving renal function. In the remaining child that received delayed PSL therapy, persistent elevations of urinary beta2MG ratio and TI scores were observed. He subsequently progressed to chronic renal insufficiency. These clinical findings suggest that persistent elevations of urinary beta2MG ratio and TI scores are indicators of progression of renal failure in TIN. For successful treatment, early therapeutic intervention should be deployed in selected patients with severe idiopathic TIN.

Tubulointerstitial nephritis and uveitis syndrome in Southern Spain

OBJECTIVE

To examine immunogenetic and clinical features in a series of patients with the idiopathic tubulointerstitial nephritis and uveitis (TINU) syndrome diagnosed at the single referral hospital for a defined population in Southern Spain.

PATIENTS AND METHODS

Retrospective study of the case records of all patients diagnosed with the TINU syndrome in the Departments of Ophthalmology and Medicine of the Valme University Hospital (Seville, Spain) from January 1996 through October 2000. Patients were included in this study if they had a renal biopsy showing interstitial edema and infiltration by lymphocytes, plasma cells, macrophages, eosinophils, and neutrophils. In these cases fibrosis was occasionally seen, but no glomerular changes were found. In addition, a diagnosis of uveitis by expert ophthalmologists was always required. Underlying diseases, which might be responsible for the renal or ocular manifestations, were excluded. Patients were HLA-DRB1 genotyped from DNA by using molecular-based methods.

RESULTS

Six patients (4 females) fulfilled the definitions described above. Four were younger than 18 years. In addition to tubulointerstitial nephritis, non-granulomatous uveitis (anterior or panuveitis) associated with low visual acuity was present at the time of diagnosis. Leukocytosis and increase of acute phase reactants were also commonly observed at the time of diagnosis. Topical and oral corticosteroids were prescribed to all the patients. Cyclosporine A therapy was required in 2 cases. After a 2.5-year median follow-up, visual acuity had improved in all cases. Of note, 4 of 6 patients carried the HLA-DRB1*01 allele.

CONCLUSION

The TINU syndrome should be considered in the differential diagnosis of patients presenting with visual and renal manifestations. The presence of renal dysfunction in patients with uveitis may be of some help, as a warning sign, for the recognition of patients who require a rapid diagnosis and therapy. In Southern Spain, the TINU syndrome appears to be associated with HLA-DRB1*01 allele.

Fluorescein angiographic features of tubulointerstitial nephritis and uveitis syndrome

OBJECTIVE

To explain fluorescein angiographic features in patients with tubulointerstitial nephritis and uveitis syndrome.

DESIGN

Retrospective observational case series.

PARTICIPANTS

Four consecutive patients with tubulointerstitial nephritis and uveitis syndrome seen at Uveitis Service of Okayama University Hospital from 1995 to 2000.

METHODS

Patients' characteristics obtained from medical records were analyzed. In addition, characteristics of 15 patients reported previously as case reports in the Japanese literature were reviewed.

MAIN OUTCOME MEASURES

Clinical and fluorescein angiographic features.

RESULTS

The present four patients showed varying degrees of retinal capillary leakage on fluorescein angiography, ranging from capillary leakage limited to the peripheral fundus to cystoid macular edema. The same angiographic features were found in 15 patients reported previously in the Japanese literature.

CONCLUSIONS

Retinal capillary leakage of varying degrees was a common fluorescein angiographic feature in patients with tubulointerstitial nephritis and uveitis syndrome. Fluorescein angiography is valuable in assessing the extent of retinal involvement.

The tubulointerstitial nephritis and uveitis syndrome

The world's medical literature on tubulointerstitial nephritis and uveitis (TINU) syndrome was reviewed, and data on 133 patients with TINU syndrome were identified. The median age of onset was 15 years (range 9-74 years) with a 3:1 female-to-male predominance. Common laboratory abnormalities included elevated Westergren erythrocyte sedimentation rates and elevated urinary beta-2-microglobulin levels. Ocular symptoms preceded systemic symptoms in 21% of cases, and followed systemic symptoms by up to 14 months in 65% of cases. Uveitis involved only the anterior segment in 80% of cases. Uveitis was bilateral at presentation in 77% of cases. Patients were treated with systemic corticosteroids in 80% of cases and with immunosuppressive drugs in 9% of cases. Uveitis recurred or followed a chronic course in 56% of patients and persisted for several years in some cases. Ocular complications (including posterior synechiae, cataracts, and elevated intraocular pressure) were reported in 21% of cases. The visual prognosis appears to be good. Persistent renal dysfunction was reported in 11% of cases, including five patients who required renal dialysis. TINU syndrome is a distinct clinical entity that may be under-recognized and may account for some cases of unexplained chronic or recurrent uveitis. It is important for ophthalmologists, nephrologists, and primary care providers to be familiar with this disorder to ensure early diagnosis and appropriate treatment.