Dysmorphic vs. Isomorphic Hematuria in the Diagnostic Approach to Glomerular Diseases

Background: Dysmorphic hematuria has been associated with glomerulonephritis(GN).The detection of dysmorphism is a qualitative analysis with high specificity and variable sensitivity.The objetive was to evaluate patients diagnosed with GN by assessing the prevalence of dysmorphic and isomorphic microhematuria, as well as factors associated with the presence of dysmorphic hematuria. Methods: We analyzed patients diagnosed of glomerulonephritis(GN) at our hospital.Clinical and laboratory data were collected, including the presence of isomorphic or dysmorphic hematuria and evaluated differences between groups. Results: we included 243 patients: 128 males(52.7%), mean age 54.8(±19)years; 50.2%(n=122) were hypertensive. At the time of renal biopsy, mean serum creatinine was1.94 mg/dl, estimated glomerular filtration rate(eGFR)33[14-68]mL/min and albumin to creatinine ratio was 500mg/g. The most common indication for renal biopsy was acute kidney injury and diagnoses was IgA nephropathy. Hematuria was observed in 224 patients(92.2%), of whom 77(34.3%) were dysmorphic. A higher percentage of dysmorphism was detected in IgA nephropathy. Lower prevalence of dysmorphic hematuria were detected in lupus nephritis class IV, thrombotic microangiopathy and crescentic GNs.A higher frequency of dysmorphism was noted in patients whose renal biopsy was indicated for proteinuria and hematuria or isolated hematuria(p<0.001). Younger patients(p=0.015), better renal function(p=0.013) and lower level of proteinuria(p=0.017) demonstrated a higher incidence of dysmorphism. Patients without dysmorphism had a higher prevalence of ischemic heart disease(p=0.038) and hypertension(p=0.046).In the logistic regression analysis adjusted for previous variables, nephrotic proteinuria(1.5–29.2OR:6.5,p=0.014) and better renal function(0.79–0.99 OR:0.89,p=0.039) were associated to dysmorphic hematuria. A ROC curve with an area under the curve of 0.659(0.586–0.733p<0.001) was obtained. Conclusion: In our cohort of patients diagnosed with GN, dysmorphism was detected in less than half of the cases, with a sensitivity of 77.2% and a specificity of 100%. The presence of nephrotic proteinuria and better renal function were associated with the presence of dysmorphic hematuria.