Distribution of pathologic findings in individuals with nephrotic proteinuria according to serum albumin.

BACKGROUND: Previous studies of the nephrotic syndrome have not carefully examined the relationship between serum albumin and the distribution of pathologic diagnoses found at the time of biopsy. The spectrum of pathologic findings in individuals with nephrotic proteinuria and a normal serum albumin has not been determined. Knowledge regarding the spectrum of findings in nephrotic proteinuria according to serum albumin levels may help nephrologists in the clinical decision making of when to perform a renal biopsy and in determining proper management of these patients.

METHODS: Pathologic reports of native kidney biopsies performed for idiopathic proteinuria >3 g/24 h were reviewed. Clinical characteristics and biopsy findings were compared for individuals with serum albumin <30 g/L (Group I), 30 to <35 g/L (Group II) and >/=35 g/L (Group III).

RESULTS: There were 57 patients in Group I, 20 in Group II and 35 in Group III. The proportion of individuals with focal and segmental glomerulosclerosis (FSGS) increased according to group: 26% in Group I, 45% in Group II and 74% in Group III. Of 35 patients in Group III, 34 had FSGS or advanced nephrosclerosis from another cause. Seven of 17 Group III patients with follow-up required dialysis after a mean interval of 6 years. Few of these patients received immunosuppressive therapy.

CONCLUSIONS: As serum albumin increases in the nephrotic syndrome, the proportion of patients with FSGS increases. Patients with nephrotic proteinuria and a serum albumin >35 g/L suffer from FSGS, nephrosclerosis and have poor renal survival. When evaluating nephrotic patients, nephrologists should use this knowledge about the spectrum of disease in the clinical decision making of when to perform a biopsy and in providing the patient more precise information regarding risks, benefits and alternatives of the kidney biopsy procedure.