Usefulness of a highly sensitive urinary and serum IL-6 assay in patients with diabetic nephropathy.
OBJECTIVE
Interleukin-6 (IL-6) promotes the growth of renal mesangial cells. IL-6 may play a major role in such mesangial proliferation, but there has been little research on IL-6 in relation to diabetic nephropathy because of the difficulty in measuring urinary and serum IL-6 levels. Using a newly developed, highly sensitive IL-6 assay, we studied the relationship between serum and urinary IL-6 and diabetic nephropathy.


METHODS
We investigated 72 patients with type 2 diabetes. Urinary and serum IL-6 concentrations were measured using a chemiluminescent enzyme immunoassay with a detection limit of 0.11 pg/ml.


RESULTS
There was a significant increase of the serum IL-6 level as diabetic nephropathy progressed, with the level being 1.4 +/- 0.3 pg/ml in patients with normal albuminuria, rising to 2.4 +/- 0.6 pg/ml in patients with microalbuminuria and then to 4.4 +/- 0.8 pg/ml in those having proteinuria. The serum IL-6 level was also significantly correlated with fibrinogen and aortic pulse wave velocity. The urinary IL-6 level was also significantly increased in diabetic patients as nephropathy progressed. Both serum and urinary IL-6 levels were high in the group with nephropathy, but there was no correlation between the two.


CONCLUSIONS
The urinary IL-6 level seems to be a good indicator of diabetic nephropathy, and atherosclerotic changes were related to the serum IL-6 level. The serum IL-6 may, therefore, be useful in the evaluation of atherosclerosis including nephropathy.
Shikano
M
M
Department of Nephrology, Fujita Health University, Toyoake, Japan. shikano@fujita-hu.ac.jp
Sobajima
H
H
Yoshikawa
H
H
Toba
T
T
Kushimoto
H
H
Katsumata
H
H
Tomita
M
M
Kawashima
S
S
D000419:Albuminuria / Q000097:blood / Q000652:urine; D001161:Arteriosclerosis / Q000097:blood / Q000652:urine; D003924:Diabetes Mellitus, Type 2 / Q000097:blood / Q000652:urine; D003928:Diabetic Nephropathies / Q000097:blood* / Q000652:urine*; D005260:Female; D006801:Humans; D007118:Immunoassay / Q000379:methods*; D015850:Interleukin-6 / Q000097:blood* / Q000652:urine*; D008163:Luminescent Measurements; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D012680:Sensitivity and Specificity
D015850:Interleukin-6