A specific biomarker that can separate active renal vasculitis from other causes of renal dysfunction is lacking, with a kidney biopsy often being required. Soluble CD163 (sCD163), shed by monocytes and macrophages, has been reported as a potential biomarker in diseases associated with excessive macrophage activation. Thus, we hypothesized that urinary sCD163 shed by crescent macrophages correlates with active glomerular inflammation. We detected sCD163 in rat urine early in the disease course of experimental vasculitis. Moreover, microdissected glomeruli from patients with small vessel vasculitis (SVV) had markedly higher levels of CD163 mRNA than did those from patients with lupus nephritis, diabetic nephropathy, or nephrotic syndrome. Both glomeruli and interstitium of patients with SVV strongly expressed CD163 protein. In 479 individuals, including patients with SVV, disease controls, and healthy controls, serum levels of sCD163 did not differ between the groups. However, in an inception cohort, including 177 patients with SVV, patients with active renal vasculitis had markedly higher urinary sCD163 levels than did patients in remission, disease controls, or healthy controls. Analyses in both internal and external validation cohorts confirmed these results. Setting a derived optimum cutoff for urinary sCD163 of 0.3 ng/mmol creatinine for detection of active renal vasculitis resulted in a sensitivity of 83%, specificity of 96%, and a positive likelihood ratio of 20.8. These data indicate that urinary sCD163 level associates very tightly with active renal vasculitis, and assessing this level may be a noninvasive method for diagnosing renal flare in the setting of a known diagnosis of SVV.

♦BackgroundPeritoneal dialysis (PD) is the preferred available option of renal replacement therapy for a significant number of end-stage kidney disease patients. A major limiting factor to the successful continuation of PD is the long-term viability of the PD catheter (PDC). Bedside percutaneous placement of the PDC is not commonly practiced despite published data encouraging use of this technique. Its advantages include faster recovery and avoidance of general anesthesia.♦ MethodsWe carried out a retrospective analysis of the outcomes of 313 PDC insertions at our center, comparing all percutaneous PDC insertions between July 1998 and April 2010 (group P, n = 151) with all surgical PDC insertions between January 2003 and April 2010 (group S, n = 162).♦ ResultsCompared with group P patients, significantly more group S patients had undergone previous abdominal surgery or PDC insertion (41.8% vs 9.3% and 33.3% vs 3.3% respectively, p = 0.00). More exit-site leaks occurred in group P than in group S (20.5% vs 6.8%, p = 0.002). The overall incidence of peritonitis was higher in group S than in group P (1 episode in 19 catheter–months vs 1 episode in 26 catheter–months, p = 0.017), but the groups showed no significant difference in the peritonitis rate within 1 month of catheter insertion (5% in group P vs 7.4% in group S, p = 0.4) or in poor initial drainage or secondary drainage failure (9.9% vs 11.7%, p = 0.1, and 7.9% vs 12.3%, p = 0.38, for groups P and S respectively). Technical survival at 3 months was significantly better for group P than for group S (86.6% vs 77%, p = 0.037); at 12 months, it was 77.7% and 68.7% respectively ( p = 0.126). No life-threatening complications attributable to the insertion of the PDC occurred in either group.♦ ConclusionsOur analysis demonstrates further encouraging outcomes of percutaneous PDC placement compared with open surgical placement. However, the members of the percutaneous insertion group were primarily a selected subset of patients without prior abdominal surgery or PDC insertion, therefore limiting the comparability of the groups. Studies addressing such confounding factors are required. Local expertise in catheter placement techniques may affect the generalizability of results.

High field 1H NMR spectroscopy was used for the rapid multicomponent analysis of low molecular wt compounds in urine in order to investigate the patterns of metabolic changes associated with early renal allograft dysfunction. Urine samples were collected daily for 14 days from 33 patients who underwent primary renal allograft transplantation, and analyzed by 500 and/or 600 MHz 1H NMR spectroscopy. All patients received 20 mg prednisolone and 5 mg/kg b.d. oral cyclosporin A (CsA) solution. In this study no patient showed clinical or histopathological evidence of CsA nephrotoxicity. For each patient the NMR-generated metabolite data were correlated with the clinical observations, graft biopsy pathology, and data from conventional laboratory techniques for assessing renal function. The NMR spectra of urine from patients with immediate functioning grafts were similar with respect to their patterns of amino acids, organic acids and organic amines, whereas the patients with delayed or non-functioning grafts showed significantly different metabolite excretion patterns. In longitudinal studies on individual patients there were increased urinary levels of trimethylamine-N-oxide (TMAO), dimethylamine (DMA), lactate, acetate, succinate, glycine and alanine during episodes of graft dysfunction. However, only the urinary concentration of TMAO was statistically significantly higher (P < 0.025) in the urine collected from patients during episodes of graft dysfunction (410 +/- 102 microM TMAO/mM creatinine) than in patients with good graft function (91 +/- 18 microM TMAO/mM creatinine) or healthy control subjects (100 +/- 50 microM TMAO/mM creatinine). These findings suggest that graft dysfunction is associated with damage to the renal medulla which causes the release of TMAO into the urine from the damaged renal medullary cells. This provides a possible novel urinary marker for post-transplant graft dysfunction. This study shows that NMR spectroscopy of biofluids, when used in combination with conventional laboratory techniques, is a valuable aid to renal transplant monitoring.

♦ Background: The percutaneous Seldinger method of peritoneal dialysis catheter (PDC) insertion has gained favor over recent years whereas traditionally it was reserved for patients considered not fit for general anesthesia. This blind technique is believed to be less safe, and is hence avoided in patients with previous laparotomy incisions. Reports on the success of this method may therefore be criticized for selection bias. In those with no prior abdominal surgery the optimal method of insertion has not been established. ♦ Methods: We retrospectively reviewed the outcomes of first-time PDC placements comparing the percutaneous (group P) and surgical (group S) insertion techniques in patients without a history of previous abdominal surgery in a single center between January 2003 and June 2010. We assessed catheter survival at 3 and 12 months postinsertion and compared complication rates between the two groups. ♦ Results: A total of 63 percutaneous and 64 surgical catheter insertions were analyzed. No significant difference was noted in catheter survival rates between group P and group S (86.2% vs 80% at 3 months, p = 0.37; and 78.3% vs 71.2% at 12 months, p = 0.42 respectively). Early and overall peritonitis rates were similar (5% vs 5.3%; p = 1, and 3.5 vs 4.9 episodes per 100 patient-months; p = 0.13 for group P and group S respectively). There were also no significant differences between the two groups in exit site leaks (15.9% in group P vs 6.3% in group S; p = 0.15), poor initial drainage (9.5% in group P vs 10.9% in group S, p = 0.34) or secondary drainage failure (7.9% in group P vs 18.8% in group S, p = 0.09).