Acanthocytes in the urine: useful tool to differentiate diabetic nephropathy from glomerulonephritis?

Analysis of clinical predictors of kidney diseases in type 2 diabetes patients based on machine learning

BACKGROUND

The heterogeneity of Type 2 Diabetes Mellitus (T2DM) complicated with renal diseases has not been fully understood in clinical practice. The purpose of the study was to propose potential predictive factors to identify diabetic kidney disease (DKD), nondiabetic kidney disease (NDKD), and DKD superimposed on NDKD (DKD + NDKD) in T2DM patients noninvasively and accurately.

METHODS

Two hundred forty-one eligible patients confirmed by renal biopsy were enrolled in this retrospective, analytical study. The features composed of clinical and biochemical data prior to renal biopsy were extracted from patients' electronic medical records. Machine learning algorithms were used to distinguish among different kidney diseases pairwise. Feature variables selected in the developed model were evaluated.

RESULTS

Logistic regression model achieved an accuracy of 0.8306 ± 0.0057 for DKD and NDKD classification. Hematocrit, diabetic retinopathy (DR), hematuria, platelet distribution width and history of hypertension were identified as important risk factors. Then SVM model allowed us to differentiate NDKD from DKD + NDKD with accuracy 0.8686 ± 0.052 where hematuria, diabetes duration, international normalized ratio (INR), D-Dimer, high-density lipoprotein cholesterol were the top risk factors. Finally, the logistic regression model indicated that DD-dimer, hematuria, INR, systolic pressure, DR were likely to be predictive factors to identify DKD with DKD + NDKD.

CONCLUSION

Predictive factors were successfully identified among different renal diseases in type 2 diabetes patients via machine learning methods. More attention should be paid on the coagulation factors in the DKD + NDKD patients, which might indicate a hypercoagulable state and an increased risk of thrombosis.

Glomerular Hematuria and the Utility of Urine Microscopy: A Review

Evaluation of hematuria and microscopic examination of urine sediment are commonly used tools by nephrologists in their assessment of glomerular diseases. Certain morphological aspects of urine red blood cells (RBCs) seen by microscopy may help in identifying the source of hematuria as glomerular or not. Recognized signs of glomerular injury are RBC casts or dysmorphic RBCs, in particular acanthocytes (ring-shaped RBCs with protruding blebs). Despite being a highly operator-dependent test, urine sediment examination revealing these signs of glomerular hematuria has demonstrated specificities and positive predictive values ranging between 90%-100% for diagnosing glomerular disease, although sensitivity can be quite variable. Hematuria is a commonly used tool for diagnosing patients with proliferative glomerulonephritis such as IgA nephropathy, antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis, and lupus nephritis, sometimes even as a surrogate for kidney involvement. Studies examining the role for hematuria in monitoring and predicting adverse outcomes in these diseases have shown inconsistent results, possibly due to inconsistent definitions that often fail to consider specific markers of glomerular hematuria such as dysmorphic RBCs, acanthocytes, or RBC casts. A consensus definition of what constitutes glomerular hematuria would help standardize use in future studies and likely improve the diagnostic and prognostic value of hematuria as a marker of glomerulonephritis.

Multi-Dose Intravenous Administration of Neutral and Cationic Liposomes in Mice: An Extensive Toxicity Study

Liposomes are widely used as delivery systems for therapeutic purposes. However, the toxicity associated with the multi-dose administration of these nanoparticles is not fully elucidated. Here, we evaluated the toxicity of the prolonged administration of liposomes composed of neutral or cationic phospholipids often used in drug and gene delivery. For that purpose, adult wild-type mice (C57Bl6) were randomly distributed into three groups receiving either vehicle (PBS), neutral, or cationic liposomes and subjected to repeated intravenous injections for a total of 10 doses administered over 3 weeks. Several parameters, including mortality, body weight, and glucose levels, were monitored throughout the trial. While these variables did not change in the group treated with neutral liposomes, the group treated with the positively charged liposomes displayed a mortality rate of 45% after 10 doses of administration. Additional urinalysis, blood tests, and behavioral assays to evaluate impairments of motor functions or lesions in major organs were also performed. The cationic group showed less forelimb peak force than the control group, alterations at the hematological level, and inflammatory components, unlike the neutral group. Overall, the results demonstrate that cationic liposomes are toxic for multi-dose administration, while the neutral liposomes did not induce changes associated with toxicity. Therefore, our results support the use of the well-known neutral liposomes as safe drug shuttles, even when repetitive administrations are needed.

Accuracy of hematuria for predicting non-diabetic renal disease in patients with diabetes and kidney disease: A systematic review and meta-analysis

AIMS

To clarify the predictive value of hematuria in patients with diabetes and non-diabetic renal disease (NDRD).

METHODS

The databases of Medline, Embase and the Cochrane Library were searched up to November 22, 2017. The pooled sensitivity, specificity, positive and negative likelihood ratio (PLR, NLR), diagnostic odds ratio (DOR), and area under the summary receiver operating characteristic (SROC) curve (AUC) were calculated using a bivariate mixed-effects regression model.

RESULTS

Thirty-eight articles were eligible, of which 35 articles with 4005 patients investigated hematuria. The pooled sensitivity and specificity of hematuria to predict NDRD were 0.42 (95% CI 0.35-0.49) and 0.72 (95% CI 0.64-0.79), respectively. The pooled PLR and NLR were 1.49 (95% CI 1.28-1.75) and 0.81 (95% CI 0.75-0.87), respectively. The DOR was 1.85 (95% CI 1.49-2.30). The pooled AUC was 0.59 (95% CI 0.54-0.63). For dysmorphic erythrocytes, the pooled sensitivity was 0.27 (95% CI 0.23-0.32), while the specificity was 0.94 (95% CI 0.91-0.97). There was heterogeneity among studies (p < 0.001), and no publication bias was identified.

CONCLUSIONS

Type 2 diabetes patients presenting with hematuria are slightly more likely to develop NDRD. Dysmorphic erythrocytes may be more useful than microhematuria in diagnosing for NDRD in type 2 diabetes with proteinuria.

Variables to Predict Nephrological Disease in General, and Glomerulonephritis in Particular, in Patients With Microhematuria

BACKGROUND

Microhematuria (MH) is a symptom frequently leading to uncertainty as to when a nephrology referral is appropriate. Because MH may be indicative of severe kidney disorders, prompt diagnosis and potential treatment initiation can be important. We aimed to identify further variables that point at a nephrological cause, in particular of glomerulonephritis (GN), when MH is diagnosed.

METHODS

A retrospective analysis of data acquired from patients attending a nephrology office due to MH was performed. Demographic information and diagnostic tests were evaluated in order to identify factors that were associated with a nephrological cause.

RESULTS

Patients with MH (n = 805) as indicated by a urine stick analysis were included. Of these, MH was confirmed by urine sediment analysis in 543 patients (67.5%). Of those, 48.3% had a nephrological cause, including 12.4% with GN and 2.9% with rapid progressive GN (RPGN). A urine dipstick finding of ≥ 250 erythrocytes per microliter, microalbuminuria and elevated leukocytes increased the probability of having a GN to 62.4%. Furthermore, the presence of microalbuminuria, GFR < 60 mL/min, history of hypertension and diabetes mellitus increased the probability for all nephrological causes to 95.4%.

CONCLUSION

There are a number of factors available that help to assess the need for a nephrology referral in patients with microhematuria.

Advanced Glycation-Modified Human Serum Albumin Evokes Alterations in Membrane and Eryptosis in Erythrocytes

Increased burden of advanced glycation end-products (AGEs) in case of hyperglycemic conditions leads to the development of retinopathy, nephropathy, and cardiovascular and neurological disorders such as Alzheimer's disease. AGEs are considered as pro-oxidants, and their accumulation increases the oxidative stress. The prolonged exposure to these AGEs is the fundamental cause of chronic oxidative stress. Abnormal morphology of red blood cells (RBCs) and excessive eryptosis has been observed in diabetes, glomerulonephritis, dyslipidemia, and obesity, but yet the contribution of extracellular AGEs remains undefined. In this study, we investigated the effect of AGEs on erythrocytes to determine their impact on the occurrence of different pathological forms of these blood cells. Specifically, carboxymethyllysine (CML), carboxyethyllysine (CEL), and Arg-pyrimidine (Arg-P) which have been reported to be the most pre-dominant AGEs formed under in vivo conditions were used in this study. Results suggested the eryptotic properties of CML, CEL, and Arg-P for RBCs, which were evident from the highly damaged cell membrane and occurrence of abnormal morphologies. Methylglyoxal-modified albumin showed more severe effects, which can be attributed to the high reactivity and pro-oxidant nature of glycation end products. These findings suggest the possible role of AGE-modified albumin towards the morphological changes in erythrocyte's membrane associated with diabetic conditions.

Dysmorphic erythrocytes are superior to hematuria for indicating non-diabetic renal disease in type 2 diabetics

AIMS/INTRODUCTION

There are sparse and limited studies on erythrocyte morphology in renal biopsy identifying nephropathic patients among type 2 diabetics. The present study sought to clarify the predictive value of dysmorphic erythrocytes in type 2 diabetics with non-diabetic renal disease and influences on hematuria.

MATERIALS AND METHODS

We examined 198 patients with type 2 diabetes who underwent kidney biopsies between 2012 and 2013. Hematuria was defined as >3 or >10 red blood cells per high-power field (RBCs/hpf) in urine sediment. If >80% of the erythrocytes were dysmorphic, glomerular hematuria was diagnosed. Clinical findings and predictive value of dysmorphic erythrocytes were compared between patients with hematuria (n = 19) and those without (n = 61). The potential risk factors for hematuria among diabetic nephropathy patients were also screened.

RESULTS

There was a statistically significant difference between the diabetic nephropathy group and the non-diabetic renal disease group (6.6 vs 16.8%; P = 0.04) when the demarcation point of hematuria was 10 RBCs/hpf. When the definition of hematuria was based on an examination of urinary erythrocyte morphology, a marked difference was seen (3.3 vs 24.8%; P < 0.001). Glomerular hematuria showed high specificity and a positive predictive value (0.97 and 0.94, respectively) in non-diabetic renal disease. A multivariate analysis showed that nephrotic syndrome was significantly associated with hematuria (odds ratio 3.636; P = 0.034).

CONCLUSIONS

Dysmorphic erythrocytes were superior to hematuria for indicating non-diabetic renal disease in type 2 diabetics. Nephrotic syndrome was an independent risk factor for hematuria.

Spectrum of renal disease in diabetes

The spectrum of renal disease in patients with diabetes encompasses both diabetic kidney disease (including albuminuric and non-albuminuric phenotypes) and non-diabetic kidney disease. Diabetic kidney disease can manifest as varying degrees of renal insufficiency and albuminuria, with heterogeneity in histology reported on renal biopsy. For patients with diabetes and proteinuria, the finding of non-diabetic kidney disease alone or superimposed on the changes of diabetic nephropathy is increasingly reported. It is important to identify non-diabetic kidney disease as some forms are treatable, sometimes leading to remission. Clinical indications for a heightened suspicion of non-diabetic kidney disease and hence consideration for renal biopsy in patients with diabetes and nephropathy include absence of diabetic retinopathy, short duration of diabetes, atypical chronology, presence of haematuria or other systemic disease, and the nephrotic syndrome.

Diabetic kidney disease; review of the current knowledge

Diabetes is the most common cause of chronic kidney disease (CKD) and end-stage renal disease (ESRD) in most parts of the world. 20 to 30% of diabetic patient have diabetic nephropathy in type 1 and type 2. Hyperglycemia is the key of nephropathy creation. Hyperglycemia also by production of toxic materials, advanced glycosylated end product (AGE), increased activity of aldose reductase has some role. Some metabolites of arachidonic acid, hemodynamic derangements and genetic factors have also some role. Although diabetic nephropathy is most common cause of nephropathy in these patients, but diabetic patients are also prone to other urinary tract and renal parenchymal disease and should not be confused with renal failure due to diabetic nephropathy. The principle of treatment of diabetic nephropathy is based on tight control of hyperglycemia, tight control of blood pressure and glomerular pressure, control of dyslipidemia, restriction of protein intake and smoking withdrawal.

Immunoglobulin G levels can predict non-diabetic renal disease in patients with type 2 diabetes mellitus

BACKGROUND

Proteinuria in patients with diabetes mellitus (DM) is sometimes caused by glomerular diseases other than diabetic nephropathy. In patients with type 2 DM (T2DM), specific predictors for non-diabetic renal disease (NDRD) are needed in addition to the traditional indicators for renal biopsy.

METHODS

From 1 January 2000 to 31 March 2011, we retrospectively enrolled 54 T2DM patients with proteinuria who had undergone renal biopsies into the present study. Associations between NDRD and 20 potential biomarkers, including serum levels of Igs and proteins associated with kidney function, and urinary protein and red blood cell levels, and hepatitis virus carrier status, were analyzed by multivariate logistic regression.

RESULTS

Multivariate logistic regression showed that reduced serum IgG (odds ratio [OR] 0.997; P = 0.006; 95% confidence interval [CI] 0.94-0.998) and creatinine (Cr; OR 0.587; P = 0.014; 95% CI 0.348-0.897) were predictors of NDRD. The area under the receiver operating characteristic curve (AUC(ROC) ) confirmed the good discriminatory power of IgG (AUC(ROC) 0.857 ± 0.058; 95% CI 0.744-0.970; P < 0.001) and Cr (AUC(ROC) 0.838 ± 0.054; 95% CI 0.732-0.943; P < 0.001). The IgG level below which the risk for NDRD increased, as calculated by obtaining the best Youden index, was 919.5 mg/dL (sensitivity 91.7%; specificity 83.3%), and the corresponding Cr level was 4.1 mg/dL (sensitivity 58.3%; specificity 96.7%).

CONCLUSION

Serum IgG levels <919.5 mg/dL and serum Cr levels <4.1 mg/dL are associated with NDRD in T2DM patients.

Proteinuria in Diabetic Patients – Is It Always Diabetic Nephropathy?

BACKGROUND

Diabetic nephropathy (dNP) is a consequence of type 1 and type 2 diabetes, typically occurring between 5 and 15 years after diabetes has been diagnosed. The coincidence of dNP and diabetic retinopathy (dRP) is well known. In this study we correlated the histological findings of the kidney biopsy with the clinically expected diagnosis of dNP.

PATIENTS AND METHODS

Over a 4-year period with a total of 326 kidney biopsies, 85 biopsies were performed on patients with diabetes. In all of these patients we had information about duration of diabetes and ophthalmological status. Additionally, data about proteinuria, urine sediment and autoantibodies were available. The nephrologist had to give the suspected diagnosis before the biopsy was performed, using the clinical data available.

RESULTS

In 57 patients (67%) dNP was predicted clinically before biopsy. In 28 patients we expected a different kind of kidney disease. Only 43 patients had dNP histologically. In 16 out of 19 patients with dRP we also found dNP. 26 patients with dNP did not have dRP. So dRP was very specific but not sensitive to predict dNP. On the other hand, all patients without dRP but acanthocytes in urine sediment had non-diabetic kidney disease (NDKD). In the case of patients with neither dRP nor acanthocytes, it was very difficult to distinguish between dNP and NDKD. Acanthocytes and antineutrophil cytoplasmatic antibodies with positive antibodies for proteinase 3 or myeloperoxidase were found only in NDKD, but ANAs were detected in a wide titer range in dNP and NDKD. The known duration of the diabetes ranged from 1 to 40 years. There were no additional parameters to differentiate this group.

CONCLUSIONS

Diabetic patients with dRP and proteinuria frequently have dNP. In patients without typical retinal findings dNP is less likely, thus a kidney biopsy is necessary to confirm the diagnosis. Additional knowledge about urine sediment and autoantibodies is helpful, but is not sufficient to differentiate NDKD from dNP in the majority of patients.