Long-term outcome of adult patients with minimal urinary abnormalities and normal renal function

To define the long-term outcome of patients with minimal urinary abnormalities (defined by the presence of microscopic hematuria with no or less than 1 gm/day proteinuria), and normal renal function (defined by a serum creatinine < 1.3 mg/dl), we retrospectively studied patients who fulfilled the above criteria and had a kidney biopsy done before the year of 1992 (i.e. at least followed up for 5 years), with a definite pathological diagnosis.

A total of 41 cases among 719 cases of primary glomerulonephritis (5.7%) were enrolled into the study. There were 19 males and 22 females with a mean age of 35.4+/-14.7 years at biopsy. The duration of renal disease was 116.0+/-60.5 months and the duration of follow-up post biopsy was 100.2+/-38.1 months. The pathological diagnosis was: IgA nephropathy (21 cases), focal glomerulosclerosis (9 cases), mesangial proliferative glomerulonephritis (8 cases), membranous glomerulonephritis (2 cases) and acute glomerulonephritis (1 case).

At the end of follow-up, 8 cases (19.5%) had a certain degree of renal insufficiency including 2 (4.9%) in end-stage renal disease. The other cases were either in complete remission (6 cases) or stable condition (27 cases) with persistent microscopic hematuria and normal renal function. The long-term outcome was not correlated with any of the following parameters: age, sex, disease duration, serum creatinine at presentation, daily protein loss at presentation, degree of glomerular change and degree of interstitial inflammatory cell infiltration. However, a poor long-term outcome was correlated with tubular atrophy (p < 0.05) and interstitial fibrosis (p < 0.05).

We conclude that a minimal urinary abnormality with normal renal function at presentation does not necessarily imply a favorable long-term outcome in certain patients. Tubular atrophy and interstitial fibrosis but not glomerular change correlates with a worse prognosis. This further emphasizes the importance of renal biopsy in such cases.