Urinary Alpha 1-microglobulin Research Articles

Biomarker Panels for Discriminating Risk of CKD Progression in Children.

We have previously studied biomarkers of tubular health (EGF), injury (KIM-1), dysfunction (alpha-1 microglobulin), and inflammation (TNFR-1, TNFR-2, MCP-1, YKL-40, suPAR), and demonstrated that plasma KIM-1, TNFR-1, TNFR-2 and urine KIM-1, EGF, MCP-1, urine alpha-1 microglobulin are each independently associated with CKD progression in children. In this study, we used bootstrapped survival trees to identify a combination of biomarkers to predict CKD progression in children. The CKiD Cohort Study prospectively enrolled children 6 months to 16 years old with an eGFR of 30-90 ml/min/1.73m2. We measured biomarkers in stored plasma and urine collected 5 months after study enrollment. The primary outcome of CKD progression was a composite of 50% eGFR decline or kidney failure. We constructed a regression tree-based model for predicting the time to the composite event, using a panel of clinically relevant biomarkers with empirically derived thresholds, in addition to conventional risk factors. Of the 599 children included, the median age was 12 years [IQR, 8 - 15], 371 (62%) were male, baseline urine protein to creatinine ratio was 0.33 [IQR: 0.12 - 0.95] mg/mg, and baseline eGFR was 53 [IQR, 40 - 66] ml/min/1.73m2. Overall, 205 (34%) children reached the primary outcome of CKD. A single regression tree-based model using the most informative predictors with data driven biomarker thresholds suggested a final set of 4 prognosis groups. In the final model, urine albumin/creatinine was the variable with the highest importance, and along with urine EGF/creatinine identified the highest risk group of 24 children, 100% of whom developed CKD progression at a median time of 1.3 years [95% CI: 1.0, 1.7]. When the regression tree-derived risk group classifications were added to prediction models including the clinical risk factors, the C-statistic increased from 0.76 [95%CI: 0.71 - 0.80] to 0.85 [95%CI: 0.81 - 0.88]. Using regression tree-based methods, we identified a biomarker panel of urine albumin/creatinine, urine EGF/creatinine, plasma KIM-1, and eGFR which significantly improved discrimination for CKD progression.

Correlation of Renal Oxygenation with Renal Function in Chronic Kidney Disease: A Preliminary Prospective Study

Introduction: Chronic hypoxia is prevalent in chronic kidney disease (CKD), and blood oxygenation level-dependent magnetic resonance imaging (BOLD-MRI) provides noninvasive evaluation of renal oxygenation. This study aimed to explore the correlation of renal oxygenation evaluated by BOLD-MRI with renal function. Methods: 97 non-dialysis patients with CKD stages 1–5 and healthy volunteers (HVs) were recruited in the study, all participants without diabetes. Based on their estimated glomerular filtration rate (eGFR), the patients were divided into two groups: CKD stages 1–3 (CKD 1–3) and CKD stages 4–5 (CKD 4–5). We measured cortical and medullary T2* (COT2* and MET2*) values in all participants by BOLD-MRI. Physiological indices were also recorded and compared among three groups. Correlation of T2* values with clinical characteristics was determined. Results: The COT2* values were significantly higher than MET2* values in all participants. The COT2* and MET2* values of three groups were ranked as HV > CKD 1–3> CKD 4–5 (p < 0.0001). There were positive correlations between the COT2* values, MET2* values and eGFR, hemoglobin (r > 0.4, p < 0.01). The 24-h urinary protein (24-h Upr) showed weak correlation with the COT2* value (rs = −0.2301, p = 0.0265) and no correlation with the MET2* value (p > 0.05). Urinary microprotein, including urinary alpha1-microglobulin, urinary beta2-microglobulin (β2-MG), and urinary retinol-binding protein (RBP), showed strong correlation with COT2* and MET2* values. According to the analysis of receiver operating characteristic curve, the optimal cut-points between HV and CKD 1–3 were “<61.17 ms” (sensitivity: 91.23%, specificity: 100%) for COT2* values and “<35.00 ms” (sensitivity: 77.19%, specificity: 100%) for MET2* values, whereas COT2* values (“<47.34 ms”; sensitivity: 90.00%, specificity: 92.98%) and MET2* values (“<25.09 ms”; sensitivity: 97.50%, specificity: 80.70%) between CKD 1–3 and CKD 4–5. Conclusion: The decline of renal oxygenation reflected on T2* values, especially in cortex, may be an effective diagnostic marker for early detection of CKD.

Clinical and prognostic values of urinary alpha1-microglobulin as a tubular marker in acute heart failure

BackgroundAlthough urinary alpha-1-microglobulin has been used as a marker of tubular dysfunction, its clinical and prognostic values in patients with acute heart failure have not been validated. MethodsWe analyzed 623 patients (74 ± 13 years old, 60.0% male) with acute heart failure in whom urinary alpha-1-microglobulin (A1MG) levels were measured as tubular markers at the time of admission. The primary endpoint was all-cause mortality. ResultsThe median levels of urinary alpha-1-microglobulin with and without correction for urinary creatinine concentration were 8.80 (interquartile range: 4.20–17.7) mg/dL and 12.9 (5.92–30.7) mg/gCr, respectively. Urinary A1MG levels were significantly correlated with all of beta-2-microglobulin (r = 0.77), N-acetyl-β-D-glucosaminidase (r = 0.51), and estimated glomerular filtration rate (r = −0.42); however, alpha-1-microglobulin was most often predicted using beta-2-microglobulin or N-acetyl-β-D-glucosaminidase. During the 488-day (interquartile range: 185–938 days) follow-up, 141 deaths occurred. Higher A1MG levels were associated with higher mortality even after adjustment for other covariates. Only A1MG, but not beta-2-microglobulin or N-acetyl-β-D-glucosaminidase, yielded incremental prognostic information in addition to the preexisting prognostic factors (net-reclassification improvement: 0.254, P = 0.023; integrated discrimination improvement: 0.015, P = 0.028). ConclusionsIn patients hospitalized due to acute heart failure, urinary alpha-1-microglobulin was a marker of tubular dysfunction. High alpha-1-microglobulin was associated with all-cause mortality independent of glomerular function and was a better predictor of mortality than urinary beta-2-microglobulin.

TCTAP A-008 Urinary Alpha1-microglobulin as a Novel Predictor for In-hospital All-cause Mortality in Patients with ST-Segment Elevation Myocardial Infarction

TCTAP A-008 Urinary Alpha1-microglobulin as a Novel Predictor for In-hospital All-cause Mortality in Patients with ST-Segment Elevation Myocardial Infarction

Urinary Alpha1-Microglobulin: A New Predictor for In-Hospital Mortality in Patients with ST-Segment Elevation Myocardial Infarction.

BackgroundAlpha1-microglobulin (A1MG) is a small molecular protein related to oxidation and inflammation. It exists in diverse body fluids, including urine. Results from urine tests are sometimes neglected when predicting in-hospital prognosis. It remains unclear whether urinary A1MG (UA1MG) can predict short-term prognosis of ST-elevated myocardial infarction (STEMI).Material/MethodsA total of 1854 hospitalized patients with acute STEMI were retrospectively enrolled in our study. Medical records were used to obtain patient demographic and clinical information, UA1MG values (which were used to divide patients into groups of low, medium, or high), and other laboratory parameters. Principal clinical outcomes of interest were all-cause in-hospital deaths, cardiac deaths, and major adverse cardiac events (MACEs).ResultsAmong the 1854 enrolled patients, 43 (2.3%) died in the hospital, of which 33 (1.8%) were cardiac deaths. MACEs were noted in 113 patients (6.1%) during hospitalization. The group with the highest UA1MG value showed a significantly higher frequency of in-hospital deaths, cardiac deaths, and MACEs, compared to those of the lowest UA1MG value group (4.4% vs. 1.0%, P<0.001; 3.1% vs. 0.6%, P<0.005; and 8.6% vs. 4.7%, P=0.007, respectively). Multivariate regression analysis revealed that UA1MG levels (odds ratio 1.109, 95% confidence interval (CI) 1.027–1.197, P=0.008) independently predicted all-cause in-hospital mortality. A UA1MG value of 3.23 mg/dL was considered as an optimal cutoff point in STEMI to predict all-cause mortality after receiver operating characteristic curve analysis (area under the curve 0.73, 95% CI 0.65–0.80, P<0.001).ConclusionsThe UA1MG value at hospital admission could be an independent prognostic factor of all-cause in-hospital mortality in patients with STEMI.

Clinical effect and mechanism of total glucosides of paeony in the adjuvant therapy for children with Henoch-Schönlein purpura nephritis: a prospective randomized controlled study

OBJECTIVE To study the clinical effect and mechanism of total glucosides of paeony (TGP) in the adjuvant therapy for children with Henoch-Schonlein purpura nephritis (HSPN). METHODS Sixty-four HSPN children with moderate proteinuria were divided into a TGP treatment group (n=34) and a routine treatment group (n=30) using a random number table. Thirty healthy children who underwent physical examination were enrolled as the healthy control group. The children in the routine treatment group were given conventional treatment alone, and those in the observation group were given TGP in addition to the conventional treatment. The two groups were compared in the clinical outcome after 4 weeks of treatment. The proportion of follicular helper T (Tfh) cells in peripheral blood and the plasma levels of interleukin-21 (IL-21) and interleukin-4 (IL-4) were measured in the healthy control group and the two HSPN groups. The changes in serum cystatin C (CysC) level and urinary alpha 1-microglobulin (A1M) concentration were compared before and after treatment in the two HSPN groups. RESULTS Compared with the healthy children before treatment, the children with HSPN had higher proportion of Tfh cells and expression levels of IL-21 and IL-4 (P < 0.01). The TGP treatment group had a higher overall response rate to treatment than the routine treatment group (94% vs 67%, P < 0.05). After treatment, both groups had reductions in the proportion of Tfh cells in peripheral blood, the expression levels of IL-21, IL-4, serum CysC, and urinary A1M concentration. The TGP treatment group had greater reductions in these indices than the routine treatment group (P < 0.01). CONCLUSIONS TGP has a marked clinical effect in the treatment of HSPN and can reduce the inflammatory response of the kidney and exert a protective effect on the kidney by inhibiting the proliferation of Tfh cells and downregulating the expression of IL-21 and IL-4 in plasma.

HCV cirrhotic patients treated with direct-acting antivirals: Detection of tubular dysfunction and resolution after viral clearance.

Hepatitis C virus (HCV) has been identified in tubular epithelial cells of infected patients; however, the presence of tubular dysfunction, which is a risk factor for chronic kidney disease (CKD), has never been examined in vivo. The present prospective longitudinal study aimed to estimate the prevalence of tubular dysfunction alone or with glomerular damage and its evolution after HCV clearance in cirrhotic patients. One hundred and thirty-five consecutive Child-Pugh A cirrhotic patients were evaluated before antiviral treatment and 6months after the end of therapy. Tubular dysfunction was evaluated by urinary alpha1-microglobulin to creatinine ratio (α1-MCR), and glomerular damage was assessed by urinary albumin to creatinine ratio (ACR). Almost all the patients (93.3%) showed a normal or mildly decreased e-GFR (KDIGO-G1/G2-categories). Tubular dysfunction was found in 23.7% (32/135) of patients, co-occurring with glomerular damage in 37.5% (12/32) of cases, while glomerular damage was found in 16.3% (22/135) of patients. In multiple logistic regression, glomerular damage and the concomitant presence of diabetes and hypertension were the only predictors significantly associated with tubular dysfunction. After HCV clearance, patients experienced a significant reduction of α1-MCR levels (21.0 vs 10.5μg/mg, P=.009) and tubular dysfunction resolved in 57.1% of subjects. Tubular dysfunction is an unrecognized feature of HCV-related kidney disease in cirrhotic patients and its presence should be primarily investigated in subjects with glomerular damage, diabetes and hypertension, despite normal e-GFR. Tubular dysfunction resolves in the majority of cases after HCV clearance; however, it may persist after antiviral treatment and further studies should evaluate its long-term impact on kidney function.

Expression and clinical significance of thrombospondin-1 and plasminogen activator inhibitor-1 in patients with mesangial proliferative glomerulonephritis.

As a common pathological type of glomerular disease in China, mesangial proliferative glomerulonephritis is related to plasminogen activator inhibitor-1 (PAI-1) and thrombospondin-1 (TSP-1). Here, this study aims to investigate the expression and clinical significance of TSP-1 and PAI-1 in patients with mesangial proliferative glomerulonephritis. Renal tissue specimens from 46 patients with mesangial proliferative glomerulonephritis admitted to this hospital were selected as the subjects, and 8 specimens of renal tissue from autopsy were used as controls. The expression levels of TSP-1 and PAI-1 were detected by immunohistochemistry and analyzed. The 24-hour urine protein, triglyceride, and total cholesterol levels of patients with severe mesangial hyperplasia were significantly higher than those of patients with mild and moderate mesangial hyperplasia, and serum albumin was lower than that of patients with mild and moderate mesangial hyperplasia (P<0.05). The 24-hour urine protein level of patients with moderate mesangial hyperplasia was higher than that of patients with mild mesangial hyperplasia while the albumin level was lower (P<0.05), but there was no significant difference in triglyceride and total cholesterol (P>0.05). There was no significant difference in creatinine clearance (Ccr) between the three groups (P>0.05).The 24-hour urine protein and urine alpha-1-microglobulin (A1M) levels in patients with renal interstitial disease were higher than those in patients without renal interstitial disease, while their Ccr level was lower (P<0.05). TSP-1 and PAI-1 were not positively expressed in the glomeruli and renal tubules of specimens of the control group. However, in mesangial hyperplasia patients, the expression of TSP-1 and PAI-1 in mesangial hyperplasia with varying degrees and in different renal tubular damage were as follows: mild degree < moderate degree < severe degree (P<0.05). The pathological changes of mesangial proliferative glomerulonephritis are related to 24- hour urine protein, triglyceride, total cholesterol level, urine A1M, and Ccr level. The expression of TSP1 and PAI-1 in the mesenchyme of glomerular and renal tubules significantly increased with the severity of the disease, suggesting that TSP-1 and PAI-1 play an important role in the occurrence and development of mesangial proliferative glomerulonephritis.

Therapy with 2′-O-Me Phosphorothioate Antisense Oligonucleotides Causes Reversible Proteinuria by Inhibiting Renal Protein Reabsorption

Antisense oligonucleotide therapy has been reported to be associated with renal injury. Here, the mechanism of reversible proteinuria was investigated by combining clinical, pre-clinical, and in vitro data. Urine samples were obtained from Duchenne muscular dystrophy (DMD) patients treated with drisapersen, a modified 2′O-methyl phosphorothioate antisense oligonucleotide (6 mg/kg). Urine and kidney tissue samples were collected from cynomolgus monkeys (Macaca fascicularis) dosed with drisapersen (39 weeks). Cell viability and protein uptake were evaluated in vitro using human conditionally immortalized proximal tubule epithelial cells (ciPTECs). Oligonucleotide treatment in DMD patients was associated with an increase in urinary alpha-1-microglobulin (A1M), which returned to baseline following treatment interruptions. In monkeys, increased urinary A1M correlated with dose-dependent accumulation of oligonucleotide in kidney tissue without evidence of tubular damage. Furthermore, oligonucleotides accumulated in the lysosomes of ciPTECs and reduced the absorption of A1M, albumin, and receptor-associated protein, but did not affect cell viability when incubated for up to 7 days. In conclusion, phosphorothioate oligonucleotides appear to directly compete for receptor-mediated endocytosis in proximal tubules. We postulate that oligonucleotide-induced low molecular weight proteinuria in patients is therefore a transient functional change and not indicative of tubular damage.

The Association of Serum hsCRP and Urinary Alpha1-Microglobulin in Patients with Type 2 Diabetes Mellitus.

This study aimed to investigate the association of serum hsCRP and urinary A1MG in patients with T2DM. Numerous investigations have proven that serum hypersensitive C-reactive protein (hsCRP) concentration in patients with type 2 diabetes mellitus (T2DM) is increased. Also, increased urinary alpha-1 microglobulin (A1MG) can be an early sign of renal damage, primarily on the proximal tubules in T2DM. Little information is available with respect to the associations of serum hsCRP levels and urinary A1MG in T2DM. A total of 520 patients with T2DM were recruited to participate in this study. Serum hsCRP and UA1MG (urinary alpha1-microglobulin to creatinine ratio), UACR (urinary microalbumin to creatinine ratio), UIGG (urinary immunoglobulin G to creatinine ratio), and UTRF (urinary transferrin to creatinine ratio) were obtained. The association of serum hsCRP level and each urinary protein parameter was analyzed by using the regression analysis, respectively. LnhsCRP was positively associated with the lnUA1MG in all three linear regression models (adjusted β in model 3=0.122, SE=0.027, P<0.001). Furthermore, the high hsCRP group (hsCRP > 3mg/L) was associated with increasing risk of high UA1MG (adjusted OR in model 3=1.610, 95% CI 1.037–2.499, P=0.034) by logistic regression. This study suggests that serum hsCRP levels independently associate with UA1MG in patients with T2DM. Further research is warranted to elucidate these interactions.

Unique proximal tubular cell injury and the development of acute kidney injury in adult patients with minimal change nephrotic syndrome

BackgroundAdult patients with minimal change nephrotic syndrome (MCNS) are often associated with acute kidney injury (AKI). To assess the mechanisms of AKI, we examined whether tubular cell injuries unique to MCNS patients exist.MethodsWe performed a retrospective analysis of clinical data and tubular cell changes using the immunohistochemical expression of vimentin as a marker of tubular injury and dedifferentiation at kidney biopsy in 37 adult MCNS patients. AKI was defined by the criteria of the Kidney Disease: Improving Global Outcomes (KDIGO) Clinical Practice Guidelines for AKI.ResultsThirteen patients (35.1%) were designated with AKI at kidney biopsy. No significant differences in age, history of hypertension, chronic kidney disease, diuretics use, proteinuria, and serum albumin were noted between the AKI and non-AKI groups. Urinary N-acetyl-β-D-glucosaminidase (uNAG) and urinary alpha1-microglobulin (uA1MG) as markers of tubular injury were increased in both groups, but the levels were significantly increased in the AKI group compared with the non-AKI group. The incidence of vimentin-positive tubules was comparable between AKI (84.6%) and non-AKI (58.3%) groups, but vimentin-positive tubular area per interstitial area was significantly increased in the AKI group (19.8%) compared with the non-AKI group (6.8%) (p = 0.011). Vimentin-positive injured tubules with tubular simplification (loss of brush-border of the proximal tubule/dilated tubule with flattening of tubular epithelium) were observed in the vicinity of glomeruli in both groups, suggesting that the proximal convoluted tubules were specifically injured. Two patients exhibited relatively severe tubular injuries with vimentin positivity and required dialysis within 2 weeks after kidney biopsy. The percentage of the vimentin-positive tubular area was positively correlated with uNAG but not with uA1MG in the non-AKI group.ConclusionsProximal tubular injuries with increased uNAG exist in MCNS patients without renal dysfunction and were more severe in the AKI group than they were in the non-AKI group. The unique tubular injuries probably due to massive proteinuria might be a predisposing factor for the development of severe AKI in adult MCNS patients.

The physiological determinants of low-level urine cadmium: an assessment in a cross-sectional study among schoolchildren

BackgroundRecent studies in children have reported associations of urinary cadmium (U-Cd), used as biomarker of Cd body burden, with renal dysfunction, retarded growth and impaired cognitive development in children. Little is known, however, about factors influencing U-Cd in children and likely to act as confounders.MethodsIn a cross-sectional study involving 249 schoolchildren (mean age, 5.72 years; 138 boys), we measured the urine concentrations of cadmium, zinc, lead, albumin, alpha1-microglobulin (A1M), retinol-binding protein, β2-microglobulin and club cell protein (CC16). Determinants of U-Cd expressed per creatinine or adjusted to specific gravity were identified by multiple regression analyses.ResultsGirls and boys had similar median concentrations of U-Cd (0.22 and 0.24 μg/L, 0.33 and 0.35 μg/g creatinine, respectively). When models were run without including creatinine or specific gravity among independent variables, urinary zinc, urinary A1M and age emerged as the strongest predictors of U-Cd expressed per g creatinine or adjusted to SG. When adding creatinine among predictors, urinary creatinine emerged as an additional strong predictor correlating negatively with U-Cd per g creatinine. This strong residual influence of diuresis, not seen when adding specific gravity among predictors, linked U-Cd to U-A1M or U-CC16 through secondary associations mimicking those induced by Cd nephrotoxity.ConclusionsIn young children U-Cd largely varies with diuresis, zinc metabolism and urinary A1M. These physiological determinants, unrelated to Cd body burden, may confound the child renal and developmental outcomes associated with low-level U-Cd.

A study on the biological reference interval of urinary alpha 1-microglobulin in a group of Chinese people.

The aim of this study was to explore the possible influences of age and gender on urinary Alpha 1-Microglobulin (α1-MG) concentrations and establish specific reference values of urinary α1-MG in a group of healthy adults. Two hundred and ninety-nine adults (141 males and 158 females) aged 20-60 were selected and grouped by gender and age. Urinary levels of α1-MG were detected in morning spot-urine samples, and statistical analysis was performed to explore the association between urinary α1-MG and clinical parameters, and the differences between groups were compared. The 95th percentile of distribution was used as the normal upper limit. The value of urinary α1-MG was sex-dependent (P<0.001), the 95th percentile of urinary α1-MG of males was 26.4mg/L, whereas females was 8.6mg/L. Whereas urinary α1-microglobulin-to-creatinine ratio (α1-MG/Cr) was both gender-and age-dependent (both P<0.001), and age 30 may be the cut-off point in this study. The 95th percentile of males and females aged 20-30 was 16.9mg/g, of males aged 31-60 was 19.8mg/g, of females aged 31-60 was 28.5mg/g. The relationship between urinary α1-MG concentrations and gender, age is different from previous studies. It is recommended that hospitals and laboratories should develop their own α1-MG reference intervals based on their experimental conditions.

Urinary podocyte-associated mRNA levels correlate with proximal tubule dysfunction in early diabetic nephropathy of type 2 diabetes mellitus

AimThe study assessed mRNA expression of podocyte-associated molecules in urinary sediments of patients with type 2 diabetes mellitus (DM) in relation to urinary podocytes, biomarkers of podocyte injury and of proximal tubule (PT) dysfunction.MethodsA total of 76 patients with type 2 DM and 20 healthy subjects were enrolled in a cross-sectional study, and assessed concerning urinary podocytes, urinary mRNA of podocyte-associated genes, urinary biomarkers of podocyte damage and of PT dysfunction.ResultsWe found significant differences between urinary mRNA of podocyte-associated molecules in relation with albuminuria stage. In multivariable regression analysis, urinary mRNA of nephrin, podocin, alpha-actinin-4, CD2-associated protein, glomerular epithelial protein 1 (GLEPP1), ADAM 10, and NFκB correlated directly with urinary podocytes, albuminuria, urinary alpha1-microglobulin, urinary kidney-injury molecule-1, nephrinuria, urinary vascular endothelial growth factor, urinary advanced glycation end-products (AGE), and indirectly with eGFR (p < 0.0001, R2 = 0.808; p < 0.0001, R2 = 0.825; p < 0.0001, R2 = 0.805; p < 0.0001, R2 = 0.663; p < 0.0001, R2 = 0.726; p < 0.0001, R2 = 0.720; p < 0.0001, R2 = 0.724).ConclusionsIn patients with type 2 DM there is an association between urinary mRNA of podocyte-associated molecules, biomarkers of podocyte damage, and of PT dysfunction. GLEPP1, ADAM10, and NFκB may be considered additional candidate molecules indicative of early diabetic nephropathy. AGE could be involved in this association.

Urine alpha1-microglobulin is a better marker for early tubular dysfunction than beta2-microglobulin among tenofovir-exposed human immunodeficiency virus-infected men who have sex with men

ObjectivesMen who have sex with men are at risk of tenofovir nephrotoxicity due to its wide use in both treatment and prophylaxis for human immunodeficiency virus infection, but little is known about the urinary biomarkers of early renal dysfunction in this population. This study aims to identify useful biomarkers of early renal dysfunction among human immunodeficiency virus-infected men who have sex with men exposed to tenofovir. MethodsIn a cross-sectional study urinary alpha1-microglobulin, beta2-microglobulin, N-acetyl-β-d-glucosaminidase and albumin were measured and expressed as the ratio-to-creatinine in 239 human immunodeficiency virus-infected men who have sex with men who were treatment naïve or receiving antiretroviral therapy with tenofovir-containing or non-tenofovir-containing regimens. Additionally, 56 patients in the non-antiretroviral therapy group started a tenofovir-containing regimen and were assessed after 3 and 6 months on antiretroviral therapy. ResultsBoth the frequency of alpha1-microglobulin proteinuria (alpha1-microglobulin-creatinine ratio >25.8mg/g) and the median urinary alpha1-microglobulin-creatinine ratio were higher in the tenofovir disoproxil fumarate group than the other two groups (all p<0.05). A higher frequency of beta2-microglobulin proteinuria (beta2-microglobulin-creatinine ratio >0.68mg/g) was also observed in the tenofovir group (28.9%) compared to the non-tenofovir group (13.6%, p=0.024). There were no significant differences between groups for N-acetyl-β-d-glucosaminidase and albumin. In the longitudinal study, the median urinary alpha1-microglobulin-creatinine ratio after 3 and 6 months on tenofovir-containing therapy (16.8 and 17.3mg/g) was higher than baseline (12.3mg/g, p=0.023 and 0.011, respectively), while no statistically important changes were observed in urinary beta2-microglobulin-creatinine ratio or in the other biomarkers after 3 and 6 months on antiretroviral therapy (all p>0.05). ConclusionUrinary alpha1-microglobulin seems to be a more sensitive and stable indicator of tubular dysfunction than urinary beta2-microglobulin for assessing tenofovir-related nephrotoxicity and can be significantly altered after tenofovir exposure.

Values of Alpha 1 Microglobulin Does Not Differ between Individuals with and without Family History of Balkan Endemic Nephropathy

Aim. The aim of this study was to compare urinary alpha 1 microglobulin (A1MG) in healthy individuals with and without family burden for Balkan endemic nephropathy (BEN) in an endemic village. Methods. Otherwise healthy inhabitants with microalbuminuria or proteinuria were divided into two groups: with (n = 24) and without (n = 32) family BEN burden and screened for urinary A1MG and A1MG/urine creatinine ratio. Results. Average value of urinary A1MG was 10.35 ± 7.01 mg/L in group with and 10.79 ± 8.27 mg/L in group without family history for BEN (NS, P = 0.87). A1MG was higher than 10 mg/L in eight (33.33%) inhabitants with family history and in 12 (37.5%) without (NS, P = 0.187). Average values of urinary A1MG/creatinine ratio were 1.30 ± 1.59 and 0.94 ± 0.78 in group with and group without family BEN history (NS, P = 0.39, resp.). Elevated values of this ratio were found in 13 (54.17%) inhabitants with and 14 (43.75%) without family history for BEN (NS, P = 0.415). Conclusion. We did not find statistically significant difference in the examined markers between healthy individuals with and without family burden for BEN. We concluded that these markers are not predictive of risk for BEN.

Urinary Biomarkers for Kidney Disease in ATTR Amyloidosis

Aim: The detection and prognosis of nephropathy in transthyretin amyloidosis depends on albuminuria and renal function. Knowing that urinary levels of alpha-1 microglobulin and beta-2 microglobulin reflect tubular dysfunction while urinary alpha-2 macroglobulin implies glomerular damage, we decide investigate the diagnostic value of these markers in the patients with transthyretin amyloidosis. Methods: Serum and urinary samples collected from 30 patients and 11 asymptomatic carriers were tested for alpha-1 microglobulin, beta-2 microglobulin, alpha-2 macroglobulin, albumin, creatinine and cystatin C. Results: Pathological urinary alpha-1 microglobulin was detected in 17 patients, beta-2 microglobulin in 6 and alpha-2 macroglobulin in 5; 5 patients had albuminuria (mg/g creatinine) 30-300 and in 20 patients values >300 were present. Asymptomatic carriers did not present pathological excretion of these biomarkers and albuminuria was >30 in 1 individual. The excretion rates of alpha-1 microglobulin and beta-2 microglobulin were positively correlated with albuminuria (P<0.001), serum creatinine (P<0.05) and cystatin C (P<0.001). Urinary alpha-2 macroglobulin was almost exclusively found in the presence of albuminuria, although their levels do not correlate. Conclusion: Urinary biomarkers emerge as a potential approach to detect renal disease but unexpectedly, urinary alpha-2 macroglobulin was not a marker of the severity of albuminuria

Is the urinary biomarkers assessment a non-invasive approach to tubular lesions of the solitary kidney?

Introduction: The solitary kidney (SK) is currently debated in the literature, as living kidney donation is extensively used and the diagnosis of congenital SK is frequent. Tubulointerstitial lesions associated with adaptive phenomena may occur early within the SK. Aims: Analysis of the significance of urinary biomarkers in the assessment of tubulointerstitial lesions of the SK. Methods: A cross-sectional study of 37 patients with SK included 18 patients—acquired SK (mean age 56.44 ± 12.20 years, interval from nephrectomy 10.94 ± 9.37 years), 19 patients—congenital SK (mean age 41.52 ± 10.54 years). Urinary NAG, urinary alpha-1-microglobulin, albuminuria, eGFR (CKD-EPI equation) were measured. Results: In acquired SK, NAG increased in 60.66%, urinary alpha 1-microglobulin in 16.66%, albuminuria in 55.55% of patients. Inverse correlation with eGFR presented NAG (R2 = 0.537, p = 0.022), urinary alpha 1-microglobulin (R2 = 0.702, p = 0.001), albuminuria (R2 = 0.655, p = 0.003). In congenital SK, NAG increased in 52.63%, urinary alpha 1-microglobulin in 5.26%, albuminuria in 47.36% of patients. In this group, urinary biomarkers correlated inversely with eGFR: NAG (R2 = 0.743, p < 0.001), urinary alpha 1-microglobulin (R2 = 0.701, p = 0.001), albuminuria (R2 = 0.821, p < 0.001). Significant correlations were found between the urinary biomarkers in both groups. Conclusions: Urinary biomarkers allow a non-invasive, sensitive, early assessment of the tubular lesions of the SK. Urinary biomarkers of PT injury parallel renal function decline, thus complementing the estimation of GFR. Monitoring of PT dysfunction is mandatory in patients with SK.

Urinary low-molecular-weight protein excretion in pediatric idiopathic nephrotic syndrome

Minimal change disease (MCD) and focal segmental glomerulosclerosis (FSGS) are the most common causes of idiopathic nephrotic syndrome (INS). We have evaluated the reliability of urinary neutrophil-gelatinase-associated lipocalin (uNGAL), urinary alpha1-microglobulin (uα1M) and urinary N-acetyl-beta-D-glucosaminidase (uβNAG) as markers for differentiating MCD from FSGS. We have also evaluated whether these proteins are associated to INS relapses or to glomerular filtration rate (GFR). The patient cohort comprised 35 children with MCD and nine with FSGS; 19 healthy age-matched children were included in the study as controls. Of the 35 patients, 28 were in remission (21 MCD, 7 FSGS) and 16 were in relapse (14 MCD, 2 FSGS). The prognostic accuracies of these proteins were assessed by receiver operating characteristic (ROC) curve analyses. The level of uNGAL, indexed or not to urinary creatinine (uCreat), was significantly different between children with INS and healthy children (p = 0.02), between healthy children and those with FSGS (p = 0.007) and between children with MCD and those with FSGS (p = 0.01). It was not significantly correlated to proteinuria or GFR levels. The ROC curve analysis showed that a cut-off value of 17 ng/mg for the uNGAL/uCreat ratio could be used to distinguish MCD from FSGS with a sensitivity of 0.77 and specificity of 0.78. uβNAG was not significantly different in patients with MCD and those with FSGS (p = 0.86). Only uα1M, indexed or not to uCreat, was significantly (p < 0.001) higher for patients in relapse compared to those in remission. Our results indicate that in our patient cohort uNGAL was a reliable biomarker for differentiating MCD from FSGS independently of proteinuria or GFR levels.

Urinary beta-2 microglobulin and alpha-1 microglobulin are useful screening markers for tenofovir-induced kidney tubulopathy in patients with HIV-1 infection: a diagnostic accuracy study

Kidney tubulopathy is a well-known adverse event of antiretroviral agent tenofovir. A cross-sectional study was conducted to compare the diagnostic accuracy of five tubular markers, with a collection of abnormalities in these markers as the reference standard. The study subjects were patients with HIV-1 infection on ritonavir-boosted darunavir plus tenofovir/emtricitabine with suppressed viral load. Kidney tubular dysfunction (KTD) was predefined as the presence of at least three abnormalities in the following five parameters: β2-microglobulinuria (β2M), α1-microglobulinuria (α1M), high urinary N-acetyl-β-D-glucosaminidase (NAG), fractional excretion of phosphate (FEIP), and fractional excretion of uric acid (FEUA). Receiver operating characteristic curves and areas under the curves (AUC) were estimated, and the differences between the largest AUC and each of the other AUCs were tested using a nonparametric method. The cutoff value of each tubular marker was determined using raw data of 100% sensitivity with maximal specificity. KTD was diagnosed in 19 of the 190 (10%) patients. The AUCs (95% CIs) of each tubular marker were β2M, 0.970 (0.947-0.992); α1M, 0.968 (0.944-0.992); NAG, 0.901 (0.828-0.974); FEIP, 0.757 (0.607-0.907), and FEUA, 0.762 (0.653-0.872). The AUCs of β2M and α1M were not significantly different, whereas those of the other three markers were smaller. The optimal cutoff values with 100% sensitivity were 1,123 μg/gCr (β2M, specificity 89%), 15.4 mg/gCr (α1M, specificity 87%), 3.58 U/gCr (NAG, specificity 46%), 1.02% (FEIP, specificity 0%), and 3.92% (FEUA, specificity 12%). Urinary β2M and α1M are potentially suitable screening tools for tenofovir-induced KTD. Monitoring either urinary β2M or α1M should be useful in early detection of tenofovir nephrotoxicity.