A single cystatin C determination before coronary angiography can predict short and long-term adverse events.

BACKGROUND: Cystatin C (CyC) role in the detection of contrast induced acute kidney injury (CIAKI) is controversial. This study assessed whether a single CyC determination before coronary angiography (CA)could predict CIAKI and long-term adverse events. METHODS: CyC was assessed before CA in 713 consecutive patients. CIAKI was the primary endpoint, defined as ≥0.3 mg/dl creatinine (sCR) increase at 48 h or ≥50% in 7-days. All-cause death, cardiovascular (CV)death and MACE (acute coronary syndrome, acute pulmonary edema,CV death) were secondary endpoints. Re-hospitalization, in-hospital death and worsening renal function were tertiary endpoints. RESULTS: CIAKI occurred in 47 (6.7%) patients. ROC analysis showed a good accuracy of CyC in the prediction of CIAKI (AUC 0.82,p < 0.01), compared with baseline sCR and sCR-eGFR (AUC 0.70 and 0.75 respectively, both p < 0.01). CyC was associated with 10-year CV-death, all-cause death and MACEs (AUC 0.76,0.74 and 0.64 respectively,all p < 0.01). A CyC cut-off value of 1.4 mg/L was not only accurate in predicting or ruling-out CIAKI following CA (97% negative predictive value, 84% specificity), but also useful as a prognostic marker for 10-year adverse events (50% vs.16% all cause mortality, 29% vs.3% CV death, 39% vs.13% MACE,all p < 0.01), re-hospitalizations (54% vs.35%,p < 0.01) and worsening renal function (34% vs.19%,p < 0.01). The strongest and independent risk factor for 10-year CV death was baseline CyC>1.4 mg/L (HR 17.3, 95% CI 1.94-155.1). CONCLUSIONS: A baseline determination of CyC before CA can accurately rule out CIAKI and predict adverse events in the long term. CIAKI can be ruled out before CA in 97% patients with a CyC value < 1.4 mg/L.

Polymyxin-B hemoperfusion inactivates circulating proapoptotic factors.

OBJECTIVE: To test the hypothesis that extracorporeal therapy with polymyxin B (PMX-B) may prevent Gram-negative sepsis-induced acute renal failure (ARF) by reducing the activity of proapoptotic circulating factors. SETTING: Medical-Surgical Intensive Care Units. PATIENTS AND INTERVENTIONS: Sixteen patients with Gram-negative sepsis were randomized to receive standard care (Surviving Sepsis Campaign guidelines) or standard care plus extracorporeal therapy with PMX-B. MEASUREMENTS AND RESULTS: Cell viability, apoptosis, polarity, morphogenesis, and epithelial integrity were evaluated in cultured tubular cells and glomerular podocytes incubated with plasma from patients of both groups. Renal function was evaluated as SOFA and RIFLE scores, proteinuria, and tubular enzymes. A significant decrease of plasma-induced proapoptotic activity was observed after PMX-B treatment on cultured renal cells. SOFA and RIFLE scores, proteinuria, and urine tubular enzymes were all significantly reduced after PMX-B treatment. Loss of plasma-induced polarity and permeability of cell cultures was abrogated with the plasma of patients treated with PMX-B. These results were associated to a preserved expression of molecules crucial for tubular and glomerular functional integrity. CONCLUSIONS: Extracorporeal therapy with PMX-B reduces the proapoptotic activity of the plasma of septic patients on cultured renal cells. These data confirm the role of apoptosis in the development of sepsis-related ARF.

Urinalysis: do not forget this type of cell in renal transplantation.

Microscopic sediment analysis of urine from a 56-year-old woman who underwent renal transplantation showed many uncommon clusters of rounded and translucent cells containing globular mucous cytoplasmic inclusions (HPF, x400). These cells were bigger than leukocytes and, compared with uroepithelial cells, showed a smaller nucleus to cytoplasm ratio and appeared eosinophilic, being pink rather than azurophilic with Sternheimer-Malbin stain. They were also unlikely to be tubular cells, which are usually smaller, singly distributed and associated with dysmorphic erythrocytes and/or casts and/or a worsening in renal function. A review of the patient's history showed that a pretransplantation urologic surgical treatment, including ileal bladder reconstruction, had been performed. Intestinal epithelial cells should be remembered when examining urinary sediment.

Cystatin C as a marker of renal function immediately after liver transplantation.

To verify whether cystatin C may be of some use as a renal function marker immediately after orthotopic liver transplantation (OLT), we compared serum cystatin C (S(Cyst)), serum creatinine (S(cr)), and creatinine clearance (C(cr)) levels with the glomerular filtration rate (GFR). On postoperative days 1, 3, 5, and 7, S(Cyst) and S(cr) was measured in simultaneously drawn blood samples, whereas C(cr) was calculated using a complete 24-hour urine collection. The GFR was determined on the same days by means of iohexol plasma clearance (I-GFR). The correlation between 1/S(Cyst) and I-GFR was stronger than that of 1/S(cr) or C(cr) (P< 0.01). In the case of moderate reductions in I-GFR (80-60 mL/minute/1.73 m), S(cr) remained within the normal range, whereas the increase in S(cyst) was beyond its upper limit; for I-GFR reductions to lower levels (59-40 mL/minute/1.73 m), S(cr) increased slightly, whereas S(cyst) was twice its upper normal limit. When we isolated all of the I-GFR values on days 3, 5, and 7 that were > or = 30% lower than that recorded on the first postoperative day, S(Cyst)(P< 0.0001) and S(cr) (P< 0.01) levels were increased, whereas C(cr) remained unchanged (P = 0.09). Receiver operating characteristic (ROC) area-under-the-curve analysis showed that the diagnostic accuracy of S(cyst) was better than that of S(cr) and C(cr). S(cyst) levels of 1.4, 1.7, and 2.2 mg/L respectively predicted I-GFR levels of 80, 60, and 40 mL/minute/1.73 m. In conclusion, cystatin C is a reliable marker of renal function during the immediate post-OLT period, especially when the goal is to identify moderate changes in GFR.

Tailoring high-cut-off membranes and feasible application in sepsis-associated acute renal failure: in vitro studies.

BACKGROUND: As removal of pro-inflammatory cytokines is limited in conventional diffusive or convective extracorporeal therapies, we studied in two polysulphone membranes with an industrial albumin sieving coefficient of 0.05 (Type A) and 0.13 (Type B) cytokine (IL-6, IL-8, IL-1beta, IL-1ra, TNF-alpha) and plasma protein (albumin, cystatin C, total proteins) permeability profiles. Based on the convective membrane permeability, we evaluated in vitro the dialytic modality that could provide an acceptable balance between high cytokine and low albumin clearances. METHODS: Cytokine and plasma protein sieving coefficient (SC) and clearance were studied in (i) post-dilutional haemofiltration mode at 20% fixed ultrafiltration rate; (ii) haemodialysis mode (dialysate flow rate of 3 and 5 l/h); and (iii) haemodiafiltration mode (dialysate flow rate of 3 or 5 l/h with 0.5 l/h of ultrafiltrate). RESULTS: In haemofiltration mode both Type A and Type B haemodialysers at QB 150 ml/min exhibited similar median SC nearly up to 1 for IL-1beta and IL-1ra, at about 0.6 for IL-6, 0.4 for IL-8 and 0.7 for TNF-alpha, with clearance values ranging from 15 to 30 ml/min. SC were independent of blood flow and were stable throughout the whole experiment. Albumin SC was higher in Type B than in Type A and rapidly decreased from 0.2 to 0.02 and from 0.5 to 0.04 within 3 h for haemodialyser Types A and B, respectively. Cytokine SC was lower in haemodialysis than in haemodiafiltration and haemofiltration mode, and by increasing dialysate flow from 3 up to 5 l/h in both haemodialysis and haemodiafiltration mode, SC for all tested cytokines decreased. However, at 5 l/h clearances were not different or were higher, since increased amounts of dialysate outlet compensated for the decreased SC. Albumin clearances in haemodialysis and haemodiafiltration mode after 360 min at 5 l/h were 0.81 and 0.91 ml/min, respectively. CONCLUSIONS: Our studies show that a mixed convective and diffusive technique ensures high cytokine clearances with an acceptable loss of albumin.

Long-term, low-dose, intravenous vitamin C leads to plasma calcium oxalate supersaturation in hemodialysis patients.

BACKGROUND: Ascorbate supplementation for patients on regular dialysis treatment (RDT) is advised to obviate deficiency and improve epoetin response in those with functional iron deficiency. However, clear-cut safety concerns regarding hyperoxalemia are still poorly understood. This study tries to establish safety/efficacy profiles of ascorbate and oxalate during long-term intravenous ascorbate supplementation. METHODS: A prospective study was performed in 30 patients on RDT showing ascorbate deficiency (plasma ascorbate < 2.6 mg/L [<15 micromol/L]): 18 patients were administered intravenous ascorbate during 18 months (250 mg/wk, subsequently increased to 500 mg), and 12 patients were taken as reference untreated cases. Plasma ascorbate and oxalate assays and dialytic balance determinations were performed (ion chromatography and reverse-phase high-performance liquid chromatography, respectively) at baseline, during treatment, and 12 months after withdrawal. RESULTS: Plasma ascorbate levels increased dose dependently with supplementation (1.6 +/- 0.8 mg/L [9.1 +/- 4.6 mumol/L] at baseline, 2.8 +/- 1.8 mg/L [15.9 +/- 10.1 micromol/L]) with 250 mg of ascorbate, and 6.6 +/- 2.8 mg/L [37.5 +/- 16.0 micromol/L] with 500 mg/wk of ascorbate), but only normalized with greater dosages for several months in 94% of patients. Baseline plasma oxalate levels increased from 3.2 +/- 0.8 mg/L (35.8 +/- 8.8 micromol/L) to 3.6 +/- 0.8 mg/L (39.5 +/- 9.1 micromol/L) and 4.5 +/- 0.9 mg/L (50.3 +/- 10.4 micromol/L) with 250 and 500 mg, respectively ( P < 0.001). The calcium oxalate saturation threshold was exceeded by 7 of 18 patients (40%) during 6 months therapy with 500 mg/wk. Ascorbate dialysis removal increased from 37.8 +/- 23.2 mg (215 +/- 132 micromol) to 99.6 +/- 51.7 mg (566 +/- 294 micromol) during supplementation (P < 0.001), with corresponding increases in oxalate removal from 82.5 +/- 33.2 mg (917 +/- 369 micromol) to 111.2 +/- 32.6 mg/L (1,236 +/- 362 micromol; P < 0.01). Withdrawal reverted plasma levels and dialysis removal to initial values. Values for untreated patients did not change during 1 year of follow-up. CONCLUSION: Patients on RDT may resolve ascorbate deficiency with intravenous supplementation of 500 mg/wk, but this implies a significant risk for oxalate supersaturation. Oxalate measurements are strongly recommended during long-term ascorbate therapy.

Could plasma cystatin C be useful as a marker of hemodialysis low molecular weight proteins removal?

BACKGROUND: Plasma cystatin (pCyst) is a well-assessed tool for measuring renal function, and it could also play a part in hemodialysis adequacy. METHODS: pCyst and other uremic toxins (urea, creatinine, parathyroid hormone, prolactin) were assessed before and after a dialysis session in 18 hemodialysis patients: 7 on bicarbonate hemodialysis (BHD) and 11 on mixed convective dialysis (MCD; 6 standard hemodiafiltration and 5 acetate-free biofiltration). Plasma levels and reduction ratios (RR) were then compared between the BHD and MCD groups. RESULTS: The mean pre-dialysis pCyst level is nearly the same in both groups (5.3 +/- 0.8 vs. 5.7 +/- 1 mg/l, p = ns), although a substantial decrease occurs after MCD only (mean 2.4 +/- 1 vs. 6.2 +/- 2.2 mg/l after BHD, p = 0.002). The mean pCyst RR (PCRR) of 55.5% after MCD is poorly related to prolactin and urea RR, fairly comparable to parathyroid hormone RR and very close to creatinine RR (58.4%). CONCLUSIONS: Only MCD removes pCyst, but the amount of removal is different for other low molecular weight proteins (prolactin and parathyroid hormone) and similar for creatinine, a classic 'little molecule'. In view of the discrepancy of these findings, the use of pCyst in hemodialysis still seems premature and needs further studies.

The grafted kidney takes over: disappearance of the nephrotic syndrome after preemptive pancreas-kidney and kidney transplantation in diabetic nephropathy.

This report describes the rapid and complete reversal of proteinuria after preemptive transplantation in diabetic nephropathy. Case 1 was a 42-year-old woman with type 1 diabetes (before pancreas-kidney graft: serum creatinine 1.6 mg/dL and proteinuria 9.1 g/day; 1 month after pancreas-kidney graft: proteinuria 0.3 g/day and creatinine 1.3 mg/dL). Case 2 was a 48-year-old man with type 2 diabetes (before kidney graft: creatinine 2 mg/dL and proteinuria 5.9 g/day; 1 month after: proteinuria 0.7 g/day and creatinine 1.1 mg/dL). The proteinuria pattern changed (pre: glomerular nonselective, tubular complete; post: physiologic). Renal scintiscan (99mTC-MAG3) demonstrated functional exclusion of the native kidneys, despite high pretransplant clearance (> 50 mL/min). The effect was not linked to euglycemia or readily explainable by pharmacologic effects (no difference in renal parameters after pancreas transplantation with the same protocols). These data confirm the efficacy of preemptive kidney and kidney-pancreas transplantation in diabetic nephrotic syndrome and indicate that a regulatory hemodynamic effect should be investigated.

The verapamil versus amlodipine in nondiabetic nephropathies treated with trandolapril (VVANNTT) study.

BACKGROUND: We tested whether the combination of verapamil (V) or amlodipine (A) with trandolapril (T) affected proteinuria differently from T alone in patients with nondiabetic nephropathies. METHODS: After T, 2 mg, in open conditions for 1 month, 69 patients were randomly assigned to be administered T, 2 mg, combined with V, 180 mg, plus a placebo or T, 2 mg, plus A, 5 mg, once a day in a double-blind fashion. Patients were followed up for 8 months. RESULTS: Proteinuria diminished significantly after T treatment from mean protein excretion of 3,078 +/- 244 (SEM) to 2,537 +/- 204 mg/24 h (P = 0.018). In the randomized phase, there was a slight reduction in proteinuria in both groups without significant differences within and between treatments (T + V, protein from 2,335 +/- 233 to 2,124 +/- 247 mg/24 h; T + A, protein from 2,715 +/- 325 to 2,671 +/- 469 mg/24 h). The selectivity index (SI; calculated as the ratio of immunoglobulin G to albumin clearance) was slightly and not significantly reduced in patients treated with T plus V from a median of 0.20 (interquartile range, 0.13) to 0.16 (interquartile range, 0.15; P = not significant), whereas it significantly increased from 0.20 (interquartile range, 0.14) to 0.30 (interquartile range, 0.14; P = 0.0001) in patients treated with T plus A. Modifications in SI and serum creatinine levels at the end of the study from randomization were significantly directly correlated (r = 0.45; P = 0.001). The number of patients reporting adverse effects was significantly higher in the T plus A than T plus V group (63.8% versus 33.3%; P = 0.016). CONCLUSION: In patients with nondiabetic proteinuric nephropathies treated with T, the combination of V or A does not significantly increase its antiproteinuric effect.

Biochemical and microscopic urinalysis: time and cost in a nephrology laboratory.

BACKGROUND: Urinalysis is a fundamental test in internal medicine and nephrology. Figures for costs are available in the general laboratory, where biochemical and microscopic urinalysis are commonly performed as semiautomated screening tests. Information on costs is lacking in the nephrology laboratory, where a time-consuming morphological analysis is usually preferred. This study analyses the costs of urinalysis in a nephrology laboratory. METHODS: In the nephrology laboratory at the University of Turin - Italy, biochemical urinalysis consists of multi-property strip and proteinuria/creatininuria, done by laboratory technicians. Phase-contrast microscopy is done by a nephrologist or biologist. Time dedicated to the tests was recorded by the same operator over 20 working days, during which 350 urine samples were processed (median 19/day, range 842). The production costs were calculated with the logic bottom-up technique. RESULTS: Overall time needed was 11.9 minutes/sample. Biochemical urinalysis required 6.6 minutes/sample; time required and samples processed were inversely related (< or =19 samples: 7.95 minutes/sample; >19 samples: 5.6 minutes/sample, p=0.01). Microscopic urinalysis took 5.3 minutes/slide; the best time-to-samples ratio was at 18-22 samples per day (with peak efficiency at 21 samples: 4.6 minutes). Cost of reagents and disposables was Euro1.06/sample. Time accounted for euro 5.32/sample (technicians, nephrologist-biologist), with total direct cost of euro 6.38/sample. CONCLUSION: In a nephrology laboratory, microscopic urinalysis is a time-consuming, expensive test. Analysis of cost and modalities may be useful, in a time of budget constrains, to maintain a role for this precious semeiotic art.