Advances in Urine Microscopy.

Urine microscopy is an important tool for the diagnosis and management of several conditions affecting the kidneys and urinary tract. In this review, we describe the automated instruments, based either on flow cytometry or digitized microscopy, that are currently in use in large clinical laboratories. These tools allow the examination of large numbers of samples in short periods. We also discuss manual urinary microscopy commonly performed by nephrologists, which we encourage. After discussing the advantages of phase contrast microscopy over bright field microscopy, we describe the advancements of urine microscopy in various clinical conditions. These include persistent isolated microscopic hematuria (which can be classified as glomerular or nonglomerular on the basis of urinary erythrocyte morphology), drug- and toxin-related cystalluria (which can be a clue for the diagnosis of acute kidney injury associated with intrarenal crystal precipitation), and some inherited conditions (eg, adenine phosphoribosyltransferase deficiency, which is associated with 2,8-dihydroxyadenine crystalluria, and Fabry disease, which is characterized by unique urinary lamellated fatty particles). Finally, we describe the utility of identifying "decoy cells" and atypical malignant cells, which can be easily done with phase contrast microscopy in unfixed samples.

Lipiduria--with special relevance to Fabry disease.

Examination of the urine under the microscope using polarised light is invaluable for detecting and identifying lipid particles. Attention to the shape of these Maltese cross bearing bodies can distinguish conventional fat particles from Fabry bodies with great sensitivity and specificity across a wide phenotypic spectrum. This could be a cheap and rapid tool for screening subjects suspected of having Fabry disease for renal involvement. It remains to be seen whether there is value in integrating polarised light into automated urine microscopy machines, but potentially this could greatly help the pathologist or nephrologist in identifying unusual urinary particles, and broaden the capacity for larger scale screening.

Summary of KDIGO guideline. What do we really know about management of blood pressure in patients with chronic kidney disease?

The Kidney Disease: Improving Global Outcomes Clinical Practice Guideline for management of blood pressure (BP) in chronic kidney disease (CKD) supersedes the 2004 Kidney Disease Quality Outcomes Initiative document on this topic. The new guideline has been designed to assist clinical decision making in patients with CKD who are not receiving dialysis. The recommendations in the guideline acknowledge that no single BP target is optimal for all CKD patients and encourage individualization of treatment depending on age, the severity of albuminuria, and comorbidities. In general, the available evidence indicates that in CKD patients without albuminuria the target BP should be ≤140 mm Hg systolic and ≤90 mm Hg diastolic. However, in most patients with an albumin excretion rate of ≥30 mg/24 h (i.e., those with both micro- and macroalbuminuria), a lower target of ≤130 mm Hg systolic and ≤80 mm Hg diastolic is suggested. In achieving BP control, the value of lifestyle changes and the need for multiple pharmacological agents is acknowledged. Use of agents that block the renin-angiotensin-aldosterone system is recommended or suggested in all patients with an albumin excretion rate of ≥30 mg/24 h. Recommendations are almost identical in CKD patients with and without diabetes. Special considerations relevant to children and those of older age and those who have received a kidney transplant are included. Ongoing controversies in BP management in the context of CKD are highlighted along with key areas for future research.

Animal models of chronic kidney disease: useful but not perfect.

Animal models of chronic kidney disease (CKD) approximate the human condition and are keys to understanding its pathogenesis and to developing rational treatment strategies. The ethical use of animals requires a detailed understanding of the strengths and limitations of each species and the disease model, and the way in which findings can be translated from animals to humans. While not perfect, the careful use of animal experiments offers the opportunity to examine individual mechanisms in an accelerated time frame.

Long-term mineralocorticoid receptor blockade ameliorates progression of experimental diabetic renal disease.

The final end point of diabetic renal disease is the accumulation of excess collagen. A number of studies have shown that aldosterone antagonism ameliorates progression of renal fibrosis. This study was designed to examine the effect of the mineralocorticoid receptor blocker eplerenone (EPL) on progression in streptozotocin (STZ)-treated spontaneously hypertensive rats (SHR), an accelerated model of Type I diabetes. STZ-treated SHRs with a blood glucose >18 mmol/L were randomly divided into treatment (100 mg/kg/day EPL) and non-treatment groups. Sham-injected SHR animals were used as a control. Functional parameters were monitored for 16 weeks, with structural parameters assessed at completion. Both hyperglycaemic groups developed progressive albuminuria, but the increase was ameliorated by EPL from Week 12. STZ-SHRs had elevated kidney weight/body weight ratio, glomerular size, glomerular macrophages (ED-1-positive cells), tissue transforming growth factor beta 1 (TGFß1) concentrations and glomerular collagen IV staining (all P < 0.05 versus control animals). EPL reduced glomerular volume, TGFß1 expression and glomerular collagen IV without changing glomerular macrophage infiltration. The ability of EPL to ameliorate these functional and structural changes in hyperglycaemic SHRs suggest that EPL has a renoprotective role in diabetic renal disease.

Mortality in dialysis patients may not be associated with ESA dose: a 2-year prospective observational study.

BACKGROUND: Anaemia of chronic kidney disease increases the risk of death and adverse events, but can be managed using erythropoiesis stimulating agents (ESAs). However, recent evidence suggests that targeting a higher haemoglobin concentration ([Hb]) increases mortality risk, and both higher [Hb] targets and ESA doses have been implicated. Nonetheless, a causative role has not been demonstrated, and this potential relationship requires further appraisal in such a complex patient group. METHODS: The relationship between the haematopoietic response to ESAs and patient survival in 302 stable, prevalent dialysis patients was explored in a prospective, single-centre study. Clinical and laboratory parameters influencing mortality and ESA resistance were analysed. Patients were stratified into 5 groups, according to their [Hb] and ESA dosage, and were followed for 2 years. RESULTS: Little difference in co-morbidities between groups was identified. 73 patients died and 36 were transplanted. Initial analysis suggested a direct relationship between mortality and ESA dosage. However, Cox proportional hazards multivariate analysis demonstrated mortality risk was associated only with age (adjusted HR per year: 1.061, 95% CI 1.031-1.092), dialysis duration (adjusted HR: 1.010, 95% CI 1.004-1.016), peripheral vascular disease (adjusted HR: 1.967, 95% CI 1.083-3.576) and CRP (adjusted HR: 1.024, 95% CI 1.011-1.039). Mortality was increased in patients poorly responsive to ESAs (55.5%). CONCLUSION: ESA dose does not appear to contribute substantially to mortality risk in dialysis patients. Instead, age and co-morbidities appear to be the critical determinants. A poor response to ESAs is a marker of overall poor health status.

Explanting is an ex vivo model of renal epithelial-mesenchymal transition.

Recognised by their de novo expression of alpha-smooth muscle actin (SMA), recruitment of myofibroblasts is key to the pathogenesis of fibrosis in chronic kidney disease. Increasingly, we realise that epithelial-mesenchymal transition (EMT) may be an important source of these cells. In this study we describe a novel model of renal EMT. Rat kidney explants were finely diced on gelatin-coated Petri dishes and cultured in serum-supplemented media. Morphology and immunocytochemistry were used to identify mesenchymal (vimentin+, α-smooth muscle actin (SMA)+, desmin+), epithelial (cytokeratin+), and endothelial (RECA+) cells at various time points. Cell outgrowths were all epithelial in origin (cytokeratin+) at day 3. By day 10, 50 ± 12% (mean ± SE) of cytokeratin+ cells double-labelled for SMA, indicating EMT. Lectin staining established a proximal tubule origin. By day 17, cultures consisted only of myofibroblasts (SMA+/cytokeratin-). Explanting is a reproducible ex vivo model of EMT. The ability to modify this change in phenotype provides a useful tool to study the regulation and mechanisms of renal tubulointerstitial fibrosis.

Targeted urine microscopy in Anderson-Fabry disease: a cheap, sensitive and specific diagnostic technique.

BACKGROUND: Anderson-Fabry disease (AFD) is an X-linked lysosomal storage disorder resulting from the deficiency of trihexosylceramide α-galactosidase (α-Gal A). The diagnosis is often missed or delayed, and specific diagnostic tests (serum α-Gal A activity, genotyping or biopsy) are expensive and not widely available. We evaluated the diagnostic potential of urine microscopy in AFD. METHODS: We studied 35 male and female AFD patients across a wide phenotypic spectrum and 21 controls with other renal diseases. Fresh urine sediment was examined under phase-contrast microscopy using polarized light for Maltese cross (MC) particles, anti-CD77 antibody to detect globotriaosylceramide (GL3, the substrate of α-Gal A), and anti-podocalyxin antibody to assess podocyte excretion. RESULTS: Characteristic MC 2 particles and anti-CD77 binding within vacuolated urinary epithelial cells were both detected in AFD with high sensitivity and specificity (MC 2 detection sensitivity 100%, 95% confidence interval (CI) 85.4-100%, specificity 100%, CI 80.8-100%; anti-CD77-binding sensitivity 97.1%, CI 83.3-99.9, specificity 100%, CI 80.8-100%). Albuminuria (urinary albumin-to-creatinine ratio, ACR) correlated with quantitative particle excretion--in low, intermediate and high MC excretors, and median ACR was 1.6, 6.9 and 20.0 mg/µmol, respectively (analysis of variance P = 0.017). Podocyte staining was positive in ~50% of all AFD patients and was similar in those with and without clinical Fabry nephropathy (FN), whether or not treated with enzyme replacement. CONCLUSIONS: Targeted urinary microscopy is a non-invasive, inexpensive, accessible and rapid diagnostic technique, especially applicable where serum α-Gal A activity and genotyping are not affordable or available. As the number of urinary MC 2 particles increases with rising albuminuria, the technique may also be useful in assessing FN burden.

Improving CKD-MBD management in haemodialysis patients: barrier analysis for implementing better practice.

BACKGROUND: Although clinical guidelines exist for optimal levels of serum markers of chronic kidney disease mineral and bone disorder (CKD-MBD), target parameters are not achieved in many haemodialysis (HD) patients. The reason for this evidence-practice gap is unclear and more information from patients and healthcare professionals is required to improve knowledge transfer. We aimed to determine potential barriers by surveying HD patients and staff about awareness and management of CKD-MBD. METHODS: A total of 136 prevalent HD patients, 25 nephrologists and 58 dialysis nurses/technicians were surveyed. Three separate questionnaires included issues of knowledge and awareness of CKD-MBD and factors limiting management (including compliance, medications and general understanding). RESULTS: Of patients surveyed, 84% had heard of phosphate, but 42% were unsure of high phosphate foods and 46% unaware of consequences of elevated phosphate. Twenty-seven percent and thirty-five percent of patients, respectively, had difficulty taking or forgetting to take phosphate binders. Seventy-four percent of patients wanted to know more about CKD-MBD (40% via written material). Of nephrologists surveyed, 76% thought non-compliance with phosphate binders was the main reason for poor control of phosphate (predominantly related to poor patient understanding); 84% thought patients wanted to know more but only 28% provided written material on CKD-MBD. Of dialysis staff surveyed, 63% thought non-compliance with binders explained poor control, the main reason being lack of patient understanding; 88% thought patients wanted to know more but only 17% provided written education. CONCLUSIONS: Implementation of an intensive educational programme, with a multi-faceted approach, for HD patients may promote better control of CKD-MBD and improve achievement of target levels.

Lateral lumbar X-ray assessment of abdominal aortic calcification in Australian haemodialysis patients.

AIM: Vascular calcification is prevalent in patients with chronic kidney disease. Abdominal aortic calcification (AAC) can be detected by X-ray, although AAC is less well documented in anatomical distribution and severity compared with coronary calcification. Using simple radiological imaging we aimed to assess AAC and determine associations in prevalent Australian haemodialysis (HD) patients. METHODS: Lateral lumbar X-ray of the abdominal aorta was used to determine AAC, which is related to the severity of calcific deposits at lumbar vertebral segments L1 to L4. Two radiologists determined AAC scores, by semi-quantitative measurement using a validated 24-point scale, on HD patients from seven satellite dialysis centres. Regression analysis was used to determine associations between AAC and patient characteristics. RESULTS: Lateral lumbar X-ray was obtained in 132 patients. Median age of patients was 69 years (range 29-90), 60% were male, 36% diabetic, median duration of HD 38 months (range 6-230). Calcification (AAC score ≥ 1) was present in 94.4% with mean AAC score 11.0 ± 6.4 (median 12). Independent predictors for the presence and severity of calcification were age (P = 0.03), duration of dialysis (P = 0.04) and a history of cardiovascular disease (P = 0.009). There was no significant association between AAC and the presence of diabetes or time-averaged serum markers of mineral metabolism, lipid status and C-reactive protein. CONCLUSIONS: AAC detected by lateral lumbar X-ray is highly prevalent in our cohort of Australian HD patients and is associated with cardiovascular disease, increasing age and duration of HD. This semi-quantitative method of determining vascular calcification is widely available and inexpensive and may assist cardiovascular risk stratification.

Small animal models of kidney disease: a review.

Animal models of renal disease have provided valuable insights into the pathogenesis of acute and chronic kidney disease. Extension of these models to the mouse has become an increasingly important with the development of gene knockout and transgenic animals. In this review we discuss a range of models that can be used to mimic the mechanisms of human renal disease. While not perfect, the careful and ethical use of these models offers the opportunity to examine individual mechanisms in an accelerated time frame.

Increased iron requirement in hemodialysis patients on antiplatelet agents or warfarin.

BACKGROUND/AIMS: Many hemodialysis patients receive antiplatelet therapy or warfarin; however, little is known about the effect of this on iron requirements. Given the association of antiplatelet therapy with bleeding we hypothesized that there should be a greater need for iron in such patients, which we tested in this study. METHODS: Retrospective 1-year cohort study of 205 chronic hemodialysis patients. The primary outcome variable was total iron dose, which was analyzed according to antiplatelet/warfarin use. Data were also collected on potential confounders, allowing for both unadjusted and adjusted (multiple regression) analysis. RESULTS: 97/205 patients received antiplatelet/warfarin therapy. This group was older, with a higher incidence of macrovascular disease and diabetes and a higher median C-reactive protein (6.0 vs. 3.75 mg/l). Overall, median iron requirement was 1,300 mg/year. In a multiple regression analysis, antiplatelet/warfarin use was associated with an additional iron requirement of 703 mg (95% confidence interval 188-1,220 mg), with the strongest effect observed in patients with normal inflammatory markers. CONCLUSION: We found a high requirement for iron in patients receiving antiplatelet agents/warfarin. We argue that the most likely mechanism for this association is chronic, low-grade blood loss, although further study is required before causality can be established.

Role of the phosphatidylinositol 3-kinase and mTOR pathways in the regulation of renal fibroblast function and differentiation.

Tubulointerstitial fibrosis is largely mediated by (myo)fibroblasts present in the interstitium. In this study, we investigated the role of mTOR and phosphatidylinositol 3-kinase in the regulation of fibroblast kinetics, fibroblast differentiation, and collagen synthesis. Rat renal fibroblasts were propagated from kidneys 3 days post-ureteric obstruction and specific inhibitors of mTOR (RAD) and phosphatidylinositol 3-kinase (LY294002) were used to examine the regulation of fibrogenesis. LY294002 but not RAD completely inhibited phosphorylation of Akt, while both inhibitors decreased phosphorylation of the S6 ribosomal protein. RAD and LY decreased foetal calf serum stimulated proliferation and DNA synthesis. In addition to their individual effects, treatment with both RAD and LY294002 decreased serum-induced fibroblast proliferation and DNA synthesis significantly more than either drug alone. TUNEL positive cells (apoptosis) in RAD and LY294002 treated groups were not different from control groups. In addition to their effect on proliferation, both inhibitors also reduced total collagen synthesis. Differentiation studies indicated an increase in alpha-smooth muscle actin expression relative to beta-actin (western blotting), with cytochemistry confirming that all doses of RAD and LY294002 increased the proportion of alpha-smooth muscle actin positive cells, and hence myofibroblasts. Effects were independent of cell toxicity. These results highlight the potential significance of PI3K and mTOR, in the regulation of renal (myo)fibroblast activity. The synergistic effects of LY and RAD on proliferation suggest that mTOR signalling involves pathways other than phosphatidylinositol 3-kinase. These results provide a novel insight into the mechanisms of fibroblast regulation during fibrogenesis.

Endogenous relaxin is a naturally occurring modulator of experimental renal tubulointerstitial fibrosis.

Relaxin is a naturally occurring regulator of collagen turnover. In this study, we determined the role of endogenous relaxin in the pathogenesis of primary tubulointerstitial fibrosis after unilateral ureteric obstruction (UUO). Four- to 6-wk-old relaxin (RLX) gene-knockout (RLX(-/-)) and age-matched wild-type (RLX(+/+)) mice, with equivalent baseline collagen levels, were subjected to UUO. Obstructed and contralateral kidneys were collected at d 0, 3, and 10 after surgery and analyzed for changes in inflammatory and fibrosis-related markers. UUO was associated with a progressive increase in fibrosis in all obstructed, but not contralateral kidneys. The increase in total collagen (hydroxyproline analysis) was associated with more alpha-smooth muscle actin (alpha-SMA) staining (myofibroblasts) and interstitial collagen sub-types (SDS-PAGE; types I, III, and V), whereas gelatin zymography demonstrated increased expression of matrix metalloproteinase-2 after surgery. By d 10 after UUO, there was a 5-fold decrease in RLX mRNA expression (quantitative RT-PCR) in RLX(+/+) animals. Total collagen and alpha-SMA expression were significantly greater in the obstructed kidneys of RLX(-/-) mice 3 d after UUO (both P < 0.05 vs. RLX(+/+) D3 after UUO), but comparable to that in RLX(+/+) animals 10 d after UUO. Administration of recombinant H2 relaxin to RLX(-/-) mice 4 d before UUO ameliorated the increase in collagen and alpha-SMA expression (both P < 0.05 vs. untreated RLX(-/-) mice) by d 3 after UUO. Expression of monocyte chemoattractant protein-1 and macrophage infiltration (inflammation) in addition to that of matrix metalloproteinases was unaffected by genotype after UUO. These combined data demonstrate that endogenous RLX acts as a modulating factor in tubulointerstitial fibrosis, a hallmark of progressive renal disease. This is likely to be via direct effects on renal myofibroblast function.

Pharmacokinetic studies of dalteparin (Fragmin), enoxaparin (Clexane), and danaparoid sodium (Orgaran) in stable chronic hemodialysis patients.

BACKGROUND: Low molecular weight heparins (LMWHs) and danaparoid are an alternative to unfractionated heparin (UH) for anticoagulation during hemodialysis. Few data are available concerning their duration of action and whether drug accumulation occurs with continued use. We performed a prospective randomized study of the pharmacokinetics of dalteparin and enoxaparin plus danaparoid in 21 hemodialysis patients. METHODS: Patients were randomly assigned to administration of enoxaparin, 40 mg; dalteparin, 2,500 U; or danaparoid, 34 U/kg, for 4 weeks. Antifactor Xa levels were measured at the end of weeks 1 and 4 immediately before the injection and at prescribed intervals up to 48 hours postinjection. RESULTS: No bleeding or thrombotic episodes occurred during the study. Mean antifactor Xa activities 4 hours postinjection were 0.2 +/- 0.035 (SEM), 0.38 +/- 0.028, and 0.54 +/- 0.051 U/mL week 1 and 0.26 +/- 0.038, 0.40 +/- 0.055, and 0.64 +/- 0.050 U/mL week 4 for dalteparin, enoxaparin, and danaparoid, respectively. Both weeks 1 and 4, antifactor Xa activity 3 hours postdose was significantly greater for danaparoid sodium compared with enoxaparin and dalteparin. There were no significant differences between antifactor Xa activity week 4 versus week 1 for enoxaparin and dalteparin; however, danaparoid sodium levels during dialysis were significantly greater after 4 weeks of treatment (P = 0.0328, 1 hour; P = 0.003, 2 hours; P = 0.0128, 3 and 4 hours). CONCLUSION: Dalteparin and enoxaparin provide adequate anticoagulation for hemodialysis using single bolus injections at relatively low doses. Danaparoid sodium at the current recommended dosage resulted in greater anticoagulation than enoxaparin or dalteparin and may have an

Which albumin should we measure?

Albumin circulates in the blood as a single homogeneous protein. During passage to the urine it can undergo configuration and digestive change, producing moieties not equally detected by the various methods currently routinely used for quantifying albuminuria. In normal urine, albumin is not the most common protein. In microalbuminuric states, detection techniques of great sensitively and specificity are required, looking for the whole molecule, immunoreactive moieties, peptide fragments, or all of these. We are unsure of the most accurate technique in terms of patient prognosis; accordingly, we must now ask "Which albumin should we measure?"