Our objective was to more precisely determine glomerular function in patients with systemic lupus erythematosus (SLE), without abnormalities in renal function, as determined by standard clinical laboratory tests. Our long-term goal is to identify patients during clinical quiescence who may be at high risk of developing progression to renal failure from lupus nephritis. We studied three groups of subjects: 8 patients with SLE and a history of nephritis, now in remission; 25 patients with SLE, without clinical evidence of nephritis, now or in the past; and 5 healthy women (normal controls). At the time of study, urinalysis, serum creatinine and 24-hour urine total protein excretion were within the normal range in each subject. We measured glomerular filtration rate (GFR) by 125I-iothalamate clearance, and albumin excretion rate (AER) by enzyme-linked immunosorbent assay (ELISA) in timed urine specimens. In addition, we compared 4-hour AER with 24-hour AER and spot urine albumin/creatinine ratio (A/C). Among patients with a history of nephritis now in remission, mean GFR was slightly but not significantly lower and mean AER was elevated (p < 0.03). Among patients with SLE without a history of nephritis, mean GFR was normal, but the variance in GFR was greater than normal (p < 0.005). Seven patients without nephritis (28%) had either hyperfiltration or hypofiltration. Mean AER was normal, but 3 other patients (12%) had elevated AER. There was no correlation of GFR and AER among patients in either group. Correlations (r) of spot urine A/C and 24-hour AER with 4-hour AER were 0.93 (p < 0.001) and 0.88 (p < 0.001), respectively.(ABSTRACT TRUNCATED AT 250 WORDS)