[Serum and urinary interleukin-6 levels in patients with primary glomerulonephritis]

Several studies have suggested that the measurement of urinary interleukin-6 (IL-6) is a helpful tool for diagnosis and monitoring the progression of glomerulonephritis. The aim of this study was to determine if IL-6 level might reflect the histological type of glomerular lesions. We performed a prospective study of 43 patients who underwent renal biopsy in our hospital. There were 35 male and 8 female patients with median age of 30.5 years (range 19-50). Included among these were 13 cases of IgA nephropathy, 11 cases of membranoproliferative glomerulonephritis, 6 cases of poststreptococcal glomerulonephritis, 6 cases of mesangial proliferative glomerulonephritis, 5 cases of membranous nephropathy and 2 cases of C3 nephritis. IL-6 was measured by ELISA (Lucernachem, Switzerland). IL-6 was not detected in the serum and rine of 15 healthy controls. IL-6 was elevated in the urine of 30 patients with different histological types of glomerular lesions (range 3.7 to 433.3 pg/ml) but was not detected in the urine of remaining 13 patients. The presence of IL-6 in the urine in absence of raised serum IL-6 suggests that urinary IL-6 was produced by the kidney. We have concluded that urinary IL-6 level can be considered as a marker of glomerulonephritis but not one that is very specific for any particular histological type of primary glomerulonephritis. Thus, the urinary IL-6 level is not a useful tool in the differential diagnosis of primary glomerulonephritis. We need further studies to determine whether urinary IL-6 level could by considered for monitoring of disease activity and therapy.