Introduction:
IgA nephropathy (IgAN) stands as the most prevalent form of glomerulonephritis and ranks among the leading causes of end-stage renal disease worldwide. Immunosuppressant therapy may further improve kidney outcomes, although the efficacy of immunological treatment, especially in the setting of impaired renal function, is unclear. To fill this knowledge gap, we retrospectively evaluated the efficacy of treatment in patients with impaired renal function by dividing patients treated with immunological treatment into three groups according to eGFR values at the time of kidney biopsy.
Methods:
A retrospective review was conducted on the medical records of the patients diagnosed with primary IgAN and treated with immunosuppressant therapy at Juntendo University Hospital from January 1, 2012 to December 31, 2021. Patients with a urine protein/creatinine ratio (UPCR) ≥ 0.5 g/gCr at the time of kidney biopsy were included in this study. These patients were divided into three groups: high eGFR group; eGFR ≧ 60, medium eGFR group; eGFR 45 to 60, low eGFR group; eGFR ≦ 45.
Results:
Total 195 patients were divided into, 141 (72.3%) in the high eGFR group, 34 (17.4%) in the medium eGFR group, and 20 (10.3%) in the low eGFR group. The low eGFR group showed higher blood pressure and massive proteinuria as well as high levels of microscopic hematuria. In fact, the degree of hematuria did not differ among the three groups. We next evaluated pathological biomarkers of IgAN in each group. such as IgA levels, IgA/C3 ratio. Serum and urine galactose-deficient IgA1 (Gd-IgA1), which is associated with IgAN disease severity, was higher in the eGFR low group. It is pretty obvious that the low eGFR group showed a higher proportion of tubular atrophy and interstitial fibrosis histologically. Meanwhile, ratio of acute lesions such as endocapillary hypercellularity and crescentic lesions also high in the low eGFR group. Next, we examined the remission rate in each group and analyzed clinical significance of persisted urinary abnormalities after immunosuppressant therapy. Remission rates of proteinuria and hematuria were 87.2% and 87.2% in the high eGFR group, 73.5% and 91.2% in the medium eGFR group, and 65.0% and 90.0% in the low eGFR group, respectively. Renal prognosis correlated with persistent proteinuria as well as microscopic hematuria. Importantly, average eGFR slope during 3years after immunosuppressant therapy in the low eGFR group was -1.1 mL/min/1.73m2 per a year.
Conclusions:
We found that in IgAN patients with impaired renal function showed high percentage of histological acute lesion with elevation of serum and urine Gd-IgA1. Thus, evaluation of disease activity of IgAN is important even in the patients with low eGFR. Low dose and short duration of immunosuppressant therapy may be useful to achieve remission. Moreover, SGLT2 inhibitor and endothelin receptor blocker in addition to RAS inhibitor may be beneficial for further reduction of proteinuria to improve renal prognosis.
I have no potential conflict of interest to disclose.
I did not use generative AI and AI-assisted technologies in the writing process.