Urinary beta 2-microglobulin as a marker for vesicoureteral reflux

Reference values for urinary protein, albumin, beta 2-microglobulin, and the alpha 1-microglobulin-to-creatinine ratio in Japanese children

BACKGROUND

The importance of the ratio of creatinine to urinary protein, albumin, and low-molecular weight protein as a urinary marker in chronic kidney disease patients is widely recognized. However, no reference values have hitherto been established for these markers in Japanese children. The present study aimed to establish the reference values for these urinary markers in Japanese children.

METHODS

The first morning urine was randomly collected from 1712 pupils aged ≥ 3 to < 18 years during school and kindergarten mass urinary screenings. The upper limit of the reference values was set at the 97.5th percentile of the creatinine ratio per marker.

RESULTS

The urinary protein-to-creatinine ratio (PCR), urinary albumin-to-creatinine ratio (ACR), urinary beta 2-microglobulin-to-creatinine ratio (BMCR), and urinary alpha 1-microglobulin-to-creatinine ratio (AMCR) showed an age-related decrease at the 50th percentile reflecting an age-related increase in urinary creatinine. The appropriate reference value for the PCR and ACR was 0.12 g/gCr and 35 mg/gCr, respectively, in the entire cohort. The appropriate reference value for the BMCR was 0.5 μg /mgCr for age ≥ 3 to < 6 years and 0.35 μg/mgCr for age 6 years or older. The appropriate reference value for the AMCR was 5.0 μg/mgCr for age ≥ 3 to < 6 years and 3.5 μg /mgCr for age 6 years or older.

CONCLUSION

The present study was the first to determine appropriate reference values for the PCR, ACR, BMCR, and AMCR based on an analysis of the first morning urine samples of a large number of children.

Increased urinary B2-microglobulin is associated with poor prognosis of upper tract urothelial carcinoma

BACKGROUND

Kidney tubular damage markers are biomarkers of acute or chronic kidney injury. Hypothetically, upper tract urothelial cancer (UTUC), which induces obstructive uropathy or direct invasion of the renal parenchyma, may also induce increased excretion of urinary tubular damage proteins. Therefore, this study aimed to investigate the use of tubular damage biomarker as prognostic markers for UTUC.

METHODS

The records of 417 surgically resected patients with UTUC were obtained from the Seoul National University Prospectively Enrolled Registry for urothelial cancer-upper tract urothelial cancer (SUPER-UC-UTUC) between January 2016 and December 2020. Patients with non-urothelial cancer or without urinary tubular injury marker measurement were excluded, and finally, 296 patients were finally included. B2-microglobulin (B2-MG) was an injury marker, and a value higher than 0.3 was considered abnormally elevated, according to previous studies.

RESULTS

The mean age was 70.9 years, and the male sex was predominant (n = 211, 71.3%). The incidences of renal pelvis and ureter cancer were similar (50.7% vs. 49.3%). Most patients had high-grade diseases (n = 254, 88.8%). The high urine B2-MG group was older, had decreased renal function, and had a higher pathologic T stage than did the low group. Multivariate Cox regression analysis of disease-free survival (DFS), open surgical method (Hazard ratio (HR) 1.52, p = 0.027), large tumor size (HR 1.06, p = 0.017), tumor multifocality (HR 1.90, p = 0.038), lymphovascular invasion (HR 2.19, p < 0.001), and high urine B2-MG (HR 1.57, p = 0.021) were significantly associated with shortened metastasis-free survival (MFS). Kaplan-Meier curve analysis revealed short DFS (median survival 15.5 months vs. unattained, log-rank p = 0.001) and MFS (unattained median survival in both groups, log-rank p = 0.003) for the high urine B2-MG group compared to the low urine B2-MG group.

CONCLUSION

Patients with UTUC presenting with increased pre-operative urine B2-MG levels were associated with disease recurrence and metastasis. This biomarker may aid in performing pre-operative risk stratification and in assessing the individual prognosis of patients with UTUC.

The Growing Epidemic of Chronic Kidney Disease: Preventive Strategies to Delay the Risk for Progression to ESRD

Hypertension, obesity and metabolic syndromes are leading risk factors for the development of chronic kidney disease (CKD). Considering the high prevalence of hypertension and obesity in children and adolescents and it's risk of progression to cardiovascular disease, CKD should be considered a serious long-term health issue in children with metabolic syndrome. Prevention of CKD requires a professional teamwork consisting of primary care physicians, nephrologists, nutritionist, pharmacist, and social work to identify and manage children at risk of developing CKD in order to provide a highly valuable management strategies. This review focuses on the principles underlying the importance of a team approach for CKD prevention.

Urinary excretion of EGF and MCP-1 in children with vesicoureteral reflux

Purpose

The aim of this study was to investigate the urinary concentration of epidermal growth factor (EGF) and monocyte chemotactic protein-1 (MCP-1) as reflux nephropathy (RN) biomarkers before and after endoscopic treatment of moderate to severe vesico-ureteral reflux (VUR).

Materials and methods

A prospective study was carried out on 72 children with moderate to severe VUR. All patients underwent endoscopic treatment using Macroplastique® or Deflux®. Vesico-ureteral reflux resolution was tested by post-operative voiding cystourethrography after 3 months and 2 years. Follow-up urinary samples were collected at that time. Control samples were taken from healthy children with no clinical evidence of renal and bladder disease and no history of UTI.

Results

In VUR patients, pre-operative urinary EGF levels had a down-regulation when compared to controls. Following successful VUR repair, urinary EGF levels of VUR children progressively increased only at long term follow-up but without returning to normal levels. Urinary MCP-1 levels were highly expressed in pre-operative samples and decreased markedly during early post-operative measurements. Urinary MCP-1 levels did not further decreased in late post-operative follow-up. In fact, these levels remained significantly higher when compared to controls.

Conclusions

Urinary levels of EGF and MCP-1 may become useful markers for monitoring the response to surgical treatment in VUR patients. Although endoscopic VUR treatment is effective in reducing the inflammatory response, the persistence of significant abnormal levels of inflammatory cytokines (such as urinary MCP-1) at long term follow-up suggests that surgery alone may not completely treat the chronic renal inflammation evidenced in these children.

The ratios of urinary β2-microglobulin and NAG to creatinine vary with age in children

BACKGROUND

Although urinary biochemical markers can be assessed by their ratio to urinary creatinine (U-Cr) concentration, reference values in adults may not be applicable to children because the amount of Cr excreted varies by body size. We therefore measured the relationship between age and the ratios of urinary β-2-microglobulin (U-β2MG), N-acetyl-β-d-glucosaminidase (U-NAG), calcium (U-Ca) and protein (U-Pr) concentration to those of U-Cr in children.

METHODS

Fifty-seven patients aged >1 year with benign familial hematuria (median age, 6.3 years) were divided into three age groups: 1-4, 5-9, and ≥10 years. Urinary biomarkers were assayed using actual values; ratios to actual U-Cr values; and our standardized metric, namely 100-fold the ratio of serum Cr to U-Cr concentration; and the relationship of each of these to age was determined.

RESULTS

The ratios of U-β2MG, U-NAG and U-Ca to Cr varied significantly by age, being higher in younger than in older children, but the actual and standardized values of each did not vary by age, nor did any measurement of U-Pr.

CONCLUSIONS

The ratios of urinary markers of tubular function, including U-β2MG, U-NAG and U-Ca, to Cr vary by age, being higher in younger children. In contrast, the ratios of urinary markers of glomerular filtration (such as U-Pr)to Cr do not vary by age, making them suitable for corrections relative to Cr.

Effects of an ACE inhibitor/calcium antagonist combination on proteinuria in diabetic nephropathy

BACKGROUND

The degree of proteinuria in patients with diabetes correlates strongly with both an increase in progression of nephropathy as well as cardiovascular events. Moreover, post hoc analyses of recent clinical trials support the concept that reductions of blood pressure and proteinuria correlate with a slowed progression of nephropathy. Both angiotensin converting enzyme (ACE) inhibitors and the nondihydropyridine calcium antagonists, (non-DHPCAs) reduce both arterial pressure and proteinuria in those with diabetic nephropathy.

METHODS

The present randomized, open label, parallel group designed study tests the hypothesis that, at similar levels of blood pressure, the combination of an ACE inhibitor, trandolapril (T) with the non-DHPCA, verapamil (V) produces a greater reduction in proteinuria over either agent alone at one year. Thirty-seven participants, mean age 59.6 +/- 5.8 years, with nephropathy (baseline creatinine 1.4 +/- 0.3 mg/dl and proteinuria of 1342 +/- 284 mg/dl) secondary to type 2 diabetes completed the study. Doses of drug were titrated in each group over eight weeks to achieve a goal blood pressure of < 140/90 mm Hg. All participants were counseled to ingest a sodium diet of < 120 mEq/day.

RESULTS

Proteinuria reduction from baseline was significantly greater in the T+V group compared to either T alone (-33 +/- 8%, T vs. -62 +/- 10%, T+V; P < 0.001) or V alone (-27 +/- 8%, V vs. -62 +/- 10%, T+V; P < 0.001). No significant differences in either glomerular filtration rate, arterial pressure, fasting blood glucose or urinary sodium excretion were noted at one year. The mean daily dose of the individual components of T+V (2.9 +/- 0.8 mg, T/219 +/- 21.1 mg V) was significantly lower than the dose of either T alone 5.5 +/- 1.1 mg/day (P < 0.01) or V alone 314.8 +/- 46.3 mg, given in two divided doses (P < 0.01).

CONCLUSION

These data support the concept that the combination of an ACE inhibitor with a non-DHPCA reduce proteinuria to a greater extent than either agent alone. This added antiproteinuric effect occurs at lower doses of each drug and is independent of further reductions in arterial pressure. These findings could have ramifications for slowing renal disease progression in patients with nephropathy from type 2 diabetes.