Immunoglobulin a nephropathy with mild renal lesions: a call in the forest for physicians and nephrologists

Abstract

Berger’s disease, or immunoglobulin A nephropathy (IgAN), is a worldwide disease that is in first place among all glomerulonephritides in incidence and prevalence. Long-term follow-up of this disease has shown that a large number of patients (20% to 40%) develop end-stage renal disease (ESRD) after 20 years from the apparent onset of the disease (1). Since the first symptoms of the disease appear in the second and third decades of life, many patients develop ESRD while they are still relatively young, active, and working. This means that IgAN is a worldwide social problem. There are several unfavorable prognostic markers such as microscopic hematuria, hypertension, proteinuria, high serum creatinine levels (2). In addition, moderate and severe renal lesions of this disease are responsible for the ESRD. In this issue of the Journal, Szeto et al (3), for the first time, emphasize the importance of the renal biopsy and follow-up in young adult IgAN patients with mild renal lesions. During a mean follow-up of 7 years, these investigators found that many of these patients developed clinical events such as persistent urinary abnormalities (42%), mild or moderate proteinuria (33%), hypertension (26%), and renal insufficiency (7%). The onset of renal insufficiency was preceded by the development of moderate proteinuria and then hypertension. The median time for progression from proteinuria to renal insufficiency was 7 years. These results show that IgAN patients with even mild renal lesions need follow-up with accurate monitoring of blood pressure and proteinuria daily. This paper makes three important points. First, patients with hematuria, whether macroscopic or microscopic, or proteinuria or both should be referred to a nephrologist for early biopsy. This approach, which is very common in Eastern countries of the world (Japan, Singapore, Hong Kong), is rare in the United States and is not frequent in all renal units of European countries. Szeto et al (3) demonstrate that early diagnosis of IgAN is very important since a small percentage of these patients may have grade 2 lesions (,30% glomerulosclerosis and interstitial lesions) and often progress to ESRD. Second, IgAN patients with mild renal lesions need long-term follow-up with daily measurement of proteinuria and monitoring of blood pressure. In fact, during the follow-up period, clinical events developed in 42% of IgAN patients who had trace proteinuria and mild renal lesions. This means that daily proteinuria is a sensitive marker to identify high-risk patients. Third, long-term follow-up of IgAN patients with mild renal lesions, hematuria, and mild proteinuria should be carried out in the Western World. Monitoring of blood pressure monthly and proteinuria daily is recommended. The published data in the literature indicate that moderate and severe renal lesions in IgAN are unfavorable prognostic markers predisposing a large percentage of patients to ESRD; therefore, the paper by Szeto et al (3) is a call in the forest to physicians and nephrologists for early referral for renal biopsy of patients with macrohematuria or microhematuria and mild proteinuria. That will lead to making a definite diagnosis of IgAN and give patients subsequent long-term follow-up. Another similar study in the Western World might be interesting, as the clinical course of mild IgAN may be different and environmental factors may influence the prognosis of the disease.