The incidence of IgG4-positive plasma cells staining TIN in patients with biopsy-proven tubulointerstitial nephritis.

AIM: IgG4 disease is rare. However, IgG4 tubulointerstitial nephritis (TIN) is the most common renal manifestation. IgG4 disease is usually associated with elevated serum IgG4 levels and other organ involvement, low-density renal lesions on enhanced CT imaging and immune activation. The incidence of IgG4-TIN may be underestimated, as staining for IgG4 is not routine. This study sought to describe the prevalence of previously undiagnosed IgG4-TIN. Due to the complexity of the diagnosis, we only attempt to look at IgG4-positive plasma cell TIN as a potential indication for IgG4 renal disease. METHODS: A retrospective review of native renal biopsies performed between 2002 and 2012 with a primary diagnosis of TIN was selected. Samples for which interstitial nephritis was secondary to a glomerular disease were excluded. The tissues were stained for IgG4 and scored by two blinded observers. Demographic and follow-up details were collected. This study was approved by the local ethics committee. RESULTS: 82 cases of interstitial nephritis from a total of 1238 renal biopsies (2002-2012) were available after staining for further assessment. 12 samples demonstrated staining consistent with the criteria for IgG4-positive plasma cell TIN, of which 3 had mildly positive staining, 7 moderately positive staining and 2 had markedly positive staining. There were no statistically significant differences in the baseline characteristics between the positive and negative staining groups. CONCLUSIONS: A number of cases of IgG4-positive plasma cell TIN were observed histologically that had been previously diagnosed as non-specific chronic TIN. IgG4-positive plasma cell TIN made up 1% of all renal biopsies performed over 10 years and 13% of all biopsies demonstrating TIN not related to glomerular disease. IgG4 staining should be considered routinely in biopsies demonstrating primary TIN.

Cefepime induced acute interstitial nephritis--a case report.

BACKGROUND: Nephrotoxicity due to drugs especially beta lactams and cephalosporins has been well recognised. Cefepime is a fourth-generation cephalosporin that is widely prescribed with few severe adverse reactions reported. Although cefepime induced neurotoxicity has frequently been reported, there is yet no reported case of acute interstitial nephritis caused by this drug. We report a biopsy proven case of acute kidney injury due to acute interstitial nephritis associated with use of cefepime for treatment of mastoiditis and temporal bone osteomyelitis. CASE PRESENTATION: A 62-year-old Caucasian female presented with symptoms of right sided mastoiditis. A brain Magnetic Resonance Imaging scan revealed presence of right sided mastoiditis with concurrent temporal bone osteomyelitis. Microbiological specimen isolated an Escherichia coli. Therapy was commenced with intravenous cefepime. After 4 weeks of therapy with intravenous cefepime she developed acute kidney injury. No other medications were taken by the patient. Urine analysis revealed non-nephrotic range proteinuria. There was no red cell casts or white cell casts. Renal biopsy confirmed acute interstitial nephritis as cause of acute kidney injury. Cefepime therapy was ceased and treatment with ciprofloxacin was given to complete the treatment course. Renal function improved only partially with conservative management without any corticosteroid use. To our knowledge this is the first report of cefepime induced interstitial nephritis. CONCLUSIONS: Although cefepime has been considered to be a safe antibiotic from nephrotoxicity point, like other cephalosporins this adverse effect can occur rarely. Physicians need to be mindful of nephrotoxicity associated with its use and careful monitoring of renal parameters should be performed in patients on prolonged therapy with cefepime.

High-sensitivity troponin as a predictor of cardiac events and mortality in the stable dialysis population.

BACKGROUND: High-sensitivity cardiac troponin T (hs-cTnT) is a biomarker used in diagnosing myocardial injury. The clinical utility and the variation of this biomarker over time remain unclear in hemodialysis (HD) and peritoneal dialysis (PD) patients. We sought to determine whether hs-cTnT concentrations were predictive of myocardial infarction (MI) and death and to examine hs-cTnT variability over a 1-year period. METHODS: A total of 393 nonacute HD and PD patients (70% HD and 30% PD) were followed in a prospective observational study for new MI and death. RESULTS: Median hs-cTnT was 57 ng/L (interquartile range, 36-101 ng/L) with no observed difference between HD and PD patients (P = 0.11). Incremental increases in mortality (P = 0.024) and MI (P = 0.001) were observed with increasing hs-cTnT quartiles. MI incidence increased significantly across quartiles in both HD and PD patients (P = 0.012 and P = 0.025, respectively), whereas mortality increased only in HD patients (P = 0.015). For every increase of 25 ng/L in hs-cTnT, the unadjusted hazard ratio (HR) was 1.10 for mortality in the whole group (95% CI, 1.04-1.16, P = 0.001) and 1.16 for MI (95% CI, 1.08-1.23, P < 0.001). Adjusted HR for mortality was 1.07 (95% CI, 1.01-1.15, P = 0.04) and 1.14 for MI (95% CI, 1.06-1.22, P < 0.001). Changes in hs-cTnT from baseline concentrations after 1 year were minimal (55 ng/L vs 53 ng/L, P = 0.22) even in patients who had an MI (P = 0.53). CONCLUSIONS: hs-cTnT appears to have a useful role in predicting MI and death in the dialysis population. Over a 1-year period concentrations remained stable even in patients who sustained a new cardiac event.