Objectives The objective of this paper was to evaluate correlations between kidney biopsy indexes (activity and chronicity) and urinary sediment findings; the secondary objective was to find which components of urinary sediment can discriminate proliferative from other classes of lupus nephritis. Methods Lupus nephritis patients scheduled for a kidney biopsy were included in our study. The morning before the kidney biopsy, we took urine samples from each patient. Receiver operating characteristic (ROC) curves were plotted to determine the area under the curve (AUC) of each test for detecting proliferative lupus nephritis; a classification tree was calculated to select a set of values that best-predicted lupus nephritis classes. Results We included 51 patients, 36 of whom were women (70.6%). Correlations of lupus nephritis activity index with the counts in the urinary sediment of erythrocytes (isomorphic and dysmorphic), acanthocytes, and leukocytes were 0.65 ( p < 0.0001) 0.62 ( p < 0.0001) and 0.22 ( p = 0.1228), respectively. Correlations of lupus nephritis chronicity index with the counts of erythrocytes, acanthocytes, and leukocytes were 0.60 ( p ≤ 0.0001), 0.52 ( p = 0.0001) and 0.17 ( p = 0.2300), respectively. Our classification tree had an accuracy of 84.3%. Conclusions Evaluation of urine sediment reflects lupus nephritis histology.

To learn more about controlling renal interstitial hydrostatic pressure (RIHP), we assessed its response to renal medullary direct interstitial volume expansion (rmDIVE = 100 μL bolus infusion/30 sec). Three experimental series (S) were performed in hydropenic, anesthetized, right‐nephrectomized, acute left renal‐denervated and renal perfusion pressure‐controlled rats randomly assigned to groups in each S. S1: Rats without hormonal clamp were contrasted before and after rmDIVE induced via 0.9% saline solution bolus (SS group) or 2% albumin in SS bolus (2% ALB + SS group). Subcapsular ΔRIHP rose slowly, progressively and similarly in both groups by ~3 mmHg. S2: Rats under hormonal clamp were contrasted before and after sham rmDIVE (time CTR group) and real rmDIVE induced via either SS bolus (SS group) or SS bolus containing the subcutaneous tissue fibroblast relaxant dibutyryl‐cAMP (SS + db‐cAMP group). ΔRIHP showed time, group, and time*group interaction effects with a biphasic response (early: ~1 mmHg; late: ~4 mmHg) in the SS group that was absent in the SS + db‐cAMP group. S3: Two groups of rats (SS and SS + db‐cAMP) under hormonal clamp were contrasted as in S2, producing similar ΔRIHP results to those of S2 but showing a slow, progressive, and indistinct decrease in renal outer medullary blood flow in both groups. These results provide highly suggestive preliminary evidence that the renal interstitium is capable of contracting reactively in vivo in response to rmDIVE with SS and demonstrate that such a response is abolished when db‐cAMP is interstitially and concomitantly infused.

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Few studies have evaluated the glomerular filtration rate (GFR) in patients with systemic lupus erythematosus (SLE). Even though the National Kidney Foundation (NKF) suggests using the equations to estimate GFR, rheumatologists continue using creatinine clearance (CCl). The main objective of our study was the assessment of different equations to estimate GFR in patients with SLE: Simplified MDRD study equation (sMDRD), CCl, Cockcroft Gault (CG), CG calculated with ideal weight (CGi), Mayo Clinic Quadratic (MCQ), and Chronic Kidney Disease Epidemiology Collaboration Equation (CKD-EPI). CKD-EPI was considered as the reference standard, and it was compared with the other equations to evaluate bias, correlation (r), sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), percentage of measurement of GFR between 70-130% of GFR measured through CKD-EPI (P30) and to compute the ROC curves. Adequacy of the 24-h urine collection was evaluated. To classify patients into GFR < 60 ml/min/1.73 m(2), the best sensitivity and NVP were obtained with sMDRD: the best PPV and specificity with MCQ. P30 was 99.3% with sMDRD, 77.5% CCl, 91.7% CG, 96.7% CGi, and 77.2% with MCQ. The lowest bias was for sMDRD and the highest for CCl. Only 159 (52.6%) urine collections were considered adequate, and when these patients were re-evaluated, the statistical results improved for CCl. CGi was better in general than CG. CCl should not be considered as an adequate GFR estimation. Ideal weight is better than real weight to calculate GFR through CG in patients with SLE.

The role of a functional renal papilla in renal interstitial hydrostatic pressure (RIHP) response to saline volume expansion (SVE, 5% bw, ~ 30 min, 0.9%) was assessed in male rats pretreated with either 0.9 % saline (CTR, 200 µl, i.a.) or 2‐bromoethylamine (BEA, 200 mg/kg, i.a.). After 7 days, RIHP (subcapsular, mmHg), renal cortical and medullary blood flows (RCBF/RMBF, L‐D, APU), urinary water (V, ml/ min/ 100 g bw), sodium (UNaV, µEq/ min/100g bw) and nitrogen oxides excretions (UNOxV, Griess, nmol/min/100g), Ht (%) and [Pr]p (g%) were measured in anesthetized animals with hormonal clamp, kidney denervation and renal perfusion pressure control at 100 mmHg (CTR: n = 9, bw = 345 ± 7 g, Uosm = 1940 ± 187 mOSM vs. BEA: n = 12, bw = 303 ± 9α g, Uosm = 371 ± 43α mOSM) during hydropenia (H), SVE, and maintained SVE (mSVE). The results are mean ± SEM. α p<0.05 between groups in the same period, * p < 0.05 vs. H in the same group. CTRBEAHSVEmSVEHSVEmSVEHt51.3±0.445.0±*0.944.2±*0.852.6±0.744.0±*1.044.0±*1.2[Pr]p5.1±0.23.2±*0.12.8±*0.25.2±0.23.3±*0.23.2±*0.2RIHP4.2±0.327.2±*4.326.0±*4.84.1±0.626.0±*1.526.0±*2.2UNOxV0.46±0.11.8±*0.42.7±*0.60.44±0.11.8±*0.52.6±*0.7RMBF431±89464±101473±95178±Î±54249±Î±54283±Î±65UNaV0.019±0.0051.07±*0.162.53±*0.420.20±Î±0.060.86±*0.121.56±Î±*0.16 Conclusions: In rats, a nonfunctional renal papilla does not attenuate enhanced RIHP, UNOxV and diuretic responses to SVE, though decreases ~35% the late natriuretic response to SVE. Apparently, RMBF is a necessary but not sufficient factor for RIHP response to SVE. Grant Funding Source: Supported by IPL's financial resources