Evaluation of red blood cell parameters provided by the UF-5000 urine auto-analyzer in patients with glomerulonephritis

Comparison of Urinary Red Blood Cell Distribution (URD) and Dysmorphic Red Blood Cells for Detecting Glomerular Hematuria: A Multicenter Study

BACKGROUND

The clinical utility of urinary red blood cell (RBC) distribution (URD) remains limited. This study aimed to compare the diagnostic performance of URD and dysmorphic RBC (dRBC) in a multicenter study.

METHODS

This study enrolled 703 patients who visited four tertiary medical centers in Korea. Patients were classified into glomerular diseases with biopsy (N = 169), renal diseases including chronic kidney disease (N = 194), nephrotic syndrome (NS; N = 88), tubulointerstitial diseases (N = 36), acute kidney injury (N = 32), others (N = 10), and extrarenal diseases (N = 174). Renal parameters, urine microscopic examination, urinalysis, and URD assessments were conducted. The diagnostic performances of dRBC and URD were evaluated.

RESULTS

Median values of both dRBC and URD were significantly elevated in patients with glomerular diseases. URD exhibited a significant correlation with dRBC (r = 0.536) and albumin creatinine ratio (r = 0.186), while no significant correlation was observed with specific gravity (r = -0.03). Among renal diseases, dRBC and URD values were notably higher in patients with NS. The agreement rate between dRBC and URD results was 78.3% (112/143), with 31 instances showing discrepancies. ROC curve analysis comparing glomerular and extrarenal diseases yielded cutoff values of 18% for dRBC and 31.9% for URD, resulting in corresponding areas under the curve (AUC) of 0.79 and 0.83, respectively.

CONCLUSIONS

URD exhibited a comparable diagnostic performance, as indicated by a similar AUC value to that of dRBC, while offering the added advantage of providing objective and standardizable results. This attribute enhances its utility as a parameter for distinguishing between patients with glomerular hematuria (GH) and those with non-GH.

UF-5000 urinary erythrocyte parameters versus urinary aberrant erythrocytes and acanthocytes for diagnosing IgA glomerular hematuria

This study evaluated the diagnostic value of the automated UF-5000 parameters and compared it with that of aberrant erythrocytes and acanthocytes classified by microscopy for identifying IgA glomerular hematuria to propose a predictive model for clinical use. It also compared correlations between erythrocyte parameters and malformed erythrocytes. Urine samples from 53 biopsy-proven IgA hematuria cases and 143 non-IGA nephropathic hematuria cases as controls were analyzed. The ratio of small red blood cells to nonlysed red blood cells (UF-sRBC%) and lysed red blood cells (lysed RBCs) showed good diagnostic performance for IgA glomerular hematuria (area under the curve [AUC] = 0.857 [P = 0.000] and AUC = 0.860 [P = 0.000], respectively). Combining UF-sRBC%, lysed RBCs, and urine protein dry chemistry improved the diagnostic accuracy (AUC = 0.967; positive predictive value [PPV] = 91.89%; negative predictive value [NPV] = 93.10%; P = 0.000). This approach surpassed traditional microscopy for aberrant erythrocytes (AUC = 0.895; PPV = 62.27%; NPV = 88.66%; P = 0.008) and acanthocytes (AUC = 0.868; PPV = 72.97%; NPV = 83.65%; P = 0.006). The erythrocyte size index was negatively correlated with the proportion of urinary aberrant erythrocytes (r = - 0.787; P = 0.000). The UF-5000 erythrocyte parameters facilitate rapid identification of IgA nephropathy and could replace manual microscopy.

Evaluation of the fully automated urine particle analyzer UF-1500

BACKGROUND AND AIMS

This study primarily assessed the performance of the UF-1500, the novel and compact model of the fully automated urine particle analyzer and evaluated its performance against the existing UF-5000 instrument.

MATERIALS AND METHODS

A total of 648 residual urine specimens were randomly collected and examined using both the UF-1500 and UF-5000 instruments as well as manual microscopy. For each parameter, the concordance rates and detection accuracy of the UF-1500 against manual microscopy were compared with the UF-5000.

RESULTS

The concordance rates between the UF-1500 and manual microscopy were 75.3%-98.5%. The UF-1500 concordance rates within one group agreement were observed to be >90%, for all parameters except for YLCs. The differences within one group agreement between the UF-1500 and manual microscopy were insignificant, in comparison to the UF-5000, with exceptions noted for ECs and YLCs. The sensitivity and specificity of the UF-1500 for RBCs, WBCs, Squa.ECs, and BACT exceeded 80%, while the positive predictive values of ECs and CASTs were below 70%.

CONCLUSION

The UF-1500 exhibited a performance that was comparable to the existing instrument, the UF-5000, and was suitable to be introduced in clinical practice. For the samples with suspected false-positive or false-negative results, a manual microscopic examination is required for accurate testing.

Microscopic hematuria as a risk factor for IgAN progression: considering this biomarker in selecting and monitoring patients

Hematuria-either macroscopic hematuria or asymptomatic microscopic hematuria-is a clinical feature typical but not specific for immunoglobulin A nephropathy (IgAN). The only biomarker supported by the Kidney Disease: Improving Global Outcomes group as a predictor of progression, identifying patients needing treatment, is proteinuria >1 g/day persistent despite maximized supportive care. However, proteinuria can occur in the setting of active glomerulonephritis or secondary to sclerotic renal lesions. Microscopic hematuria is observed in experimental models of IgAN after IgA-IgG immunocomplex deposition, activation of inflammation and complement pathways. Oxidative damage, triggered by hemoglobin release, is thought to contribute to the development of proteinuria and progression. Despite being a clinical hallmark of IgAN and having a rational relationship with its pathophysiology, the value of microscopic hematuria in assessing activity and predicting outcomes in patients with IgAN is still debated. This was partly due to a lack of standardization and day-to-day variability of microhematuria, which discouraged the inclusion of microhematuria in large multicenter studies. More recently, several studies from Asia, Europe and the USA have highlighted the importance of microhematuria assessment over longitudinal follow-up, using a systematic approach with either experienced personnel or automated techniques. We report lights and shadows of microhematuria evaluation in IgAN, looking for evidence for a more consistent consensus on its value as a marker of clinical and histological activity, risk assessment and prediction of treatment response. We propose that hematuria should be included as part of the clinical decision-making process when considering when to use immunosuppressive therapy and as part of criteria for enrollment into clinical trials to test drugs targeting the inflammatory reaction elicited by immune pathway activation in IgAN.