Immunoglobulin A nephropathy and chronic kidney disease

Immunoglobulin (Ig)A nephropathy is one of the major causes of chronic kidney disease (CKD) in Japan. Despite statutory urinalysis of industrial workers and school children, Japan unfortunately still ranks among the countries with the highest CKD-5D prevalence in the world. Topics of this review are as follow: (i) early diagnosis and treatment; (ii) influence of the period from onset to medical intervention on renal prognosis; and (iii) epidemiology of IgA nephropathy patients in Japan. Some investigators have discussed the possibility of predicting the diagnosis and prognosis of this disease. We indicated that the frequency of various casts in urinary sediments and total numbers of each type of urinary cast should provide highly convincing data for prediction of the prognosis in IgA nephropathy patients prior to renal biopsy. Furthermore, early medical intervention (anti-platelet agents, anticoagulants, angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, corticosteroids and/or tonsillectomy) may lead to better renal prognosis in patients with IgA nephropathy. In a nationwide survey on IgA nephropathy in Japan, predictive factors after 10 years were as follows: (i) male sex; (ii) under 30 years old; (iii) diastolic hypertension; (iv) heavy proteinuria; (v) mild haematuria; (vi) low serum albumin; and (vii) elevated serum creatinine and impaired renal pathology. It appears that substantial renal deterioration can be validly estimated using these predictive factors in patients with IgA nephropathy. In conclusion, early diagnosis, treatment and improvement of predictive factors for a long duration may lead to better renal prognosis in patients with IgA nephropathy.