SP166THE NATURAL COURSE OF IgA NEPHROPATHY PRESENTING WITH ISOLATED HEMATURIA AT THE TIME OF DIAGNOSIS

INTRODUCTION AND AIMS: The outcome of patients with IgA nephropathy who present with isolated microscopic hematuria at the time of diagnosis is not well studied. METHODS: We investigated the long-term prognosis of 162 patients with biopsy-proven IgA nephropathy, who presented with isolated microscopic hematuria, preserved renal function (estimated glomerular filtration rate (eGFR) ≥60ml/min/1.73m2), and minimal or no proteinuria (spot urine protein/creatinine ratio ≤0.2). RESULTS: Baseline characteristics were as follows. Mean age (SD) at the time of diagnosis was 37.9 (12.5) years, median eGFR (interquartile range) at the time of diagnosis was 97.3 (88.1-110.8) ml/min/1.73m2, and proteinuria level 0.08 (0.06-0.12). After a median follow-up period of 107 months, eGFR was 87.7 (77.9-101.9) ml/min/1.73 m2 and proteinuria 0.07 (0.05-0.11). No patients progressed to advanced chronic kidney disease (eGFR below 30 ml/min/1.73 m2). Significant proteinuria (spot urine P/C ratio >0.2) developed in 20 (12.3%) patients, and median proteinuria level in this group was 0.82 (0.33-1.36). When the group of patients who developed significant proteinuria was compared to the group of patients who did not, we found that follow-up median eGFR was significantly lower in the group with proteinuria compared to the group without proteinuria (79.1[69.4-99.1] vs. 89.3[78.9-102.1], P=0.021). There was no difference of baseline characteristics (underlying diabetes, hypertension, sex, age, baseline eGFR, and use of anti-hypertensive medication) between the 2 groups. On histopathological findings using the semiquantative classification, there was no significant difference of the median activity index score (total 10) and chronicity index score (total 12) between the 2 groups. CONCLUSIONS: Our study is one of the largest single-center studies to date on the prognosis of this cohort. As reported before, the long-term prognosis of IgA nephropathy patients with isolated hematuria at the time of diagnosis is excellent.