Dysmorphic vs. Isomorphic Microhematuria in the Diagnostic Approach of Glomerular Diseases

Background: Dysmorphic microhematuria has been related to glomerulonephritis(GN). This technique has a high specificity with variable sensitivity. The objective of study was to evaluate patients with GN and to study the prevalence of dysmorphic and isomorphic microhematuria and to evaluate factors associated with dysmorphia. Methods: Retrospective study of patients with GN associated with microhematuria in our hospital from 2013 to 2024. Clinical and analytical characteristics of the patients were analyzed comparing patients who presented or not dysmorphic red blood cells (dRBCs). Results: 119 patients diagnosed with GN were included:68 men(57.1%), mean age 51.6(±19)years, 55.5%(n=66) hypertension. At the time of the kidney biopsy, creatinine 1.8[0.9-3.6]mg/dl, eGFR 44[15-81] mL/min/m2 and albumin/creatinine ratio 650[281-1634]mg/gr. The more frequent indication of kidney biopsy was proteinuria and microhematuria(n=52, 43.7%). IgA nephropathy(n=34, 28.6%) was GN with more prevalence. 105 patients(88.2%) had microhematuria, of which 51(48.6%) had dRBCs. Patients with cryoglobulinemia, anti-GBM and IgA Nephropathy, a higher percentage of dRBCs was detected(80%, 57% and 51.6%, respectively p=0.013). A higher prevalence of dRBCs in acute kidney injury, proteinuria and microhematuria as indication of kidney biopsy (p=0.046). Furthermore, patients with hypertension(p=0.013) and men(p=0.038) presented more prevalence of dRBCs. However, patients who did not present dRBCs had a higher ischemic heart disease(p=0.019), antiplatelet agents(p=0.016), protein/creatinine ratio(p=0.043) and positive urine culture(p= 0.046). In the logistic regression analysis, low protein/creatinine ratio(1.03-9.09 OR:3.06, p=0.044) was the only variable associated with the presence of dysmorphia. A ROC curve was obtained with an AUC of 0.72(0.619- 0.822 p<0.001). The sensitivity was 31.9% and specificity 91.5%. Conclusion: Patients with GN and microhematuria, dysmorphia was detected in approximately half of patients. The absence of hypertension, ischemic heart disease, antiplatelet agents, negative urine culture and lower level of proteinuria were related to the presence of dysmorphia, with a sensitivity 31.9% and a specificity 91.5%.