Urinary L-FABP and anaemia: distinct roles of urinary markers in type 2 diabetes.
BACKGROUND
Urinary liver-type fatty acid binding protein (L-FABP) and kidney injury molecule (KIM)-1, novel urinary biomarkers of renal tubulointerstitial function, have previously been associated with acute ischaemic kidney injury. We studied the clinical significance of urinary L-FABP, KIM-1 and N-acetyl-beta-glucosaminidase (NAG) as potential markers of renal function and chronic ischaemic injury in patients with diabetic nephropathy.


METHODS
A total of 130 type 2 diabetes patients with early diabetic nephropathy and 40 healthy controls were studied. Urinary L-FABP, KIM-1, NAG, albumin excretion rate (AER) and creatinine clearance were obtained from 24-h urine samples, and correlated with measures of red blood cell count, renal function and metabolic control.


RESULTS
Urinary L-FABP was significantly increased in diabetes patients compared with healthy controls [8.1 (interquartile 0.6-11.6) vs. 2.4 (0.5-3.6) microg/g creatinine, P < 0.001] and correlated with AER (r = 0.276, P = 0.002), creatinine clearance (r = -0.189, P = 0.033) and haemoglobin levels (r = -0.190, P = 0.030). In multivariable linear regression analysis, haemoglobin (beta = -0.247, P = 0.015) and AER (beta = 0.198, P = 0.046) were significant predictors of urinary L-FABP. Prevalent anaemia was independently associated with a 6-fold risk for increased tubulointerstitial kidney damage (upper vs. lower two L-FABP tertiles: OR, 6.06; 95% CI: 1.65-22.23; P = 0.007). Urinary KIM-1 was not significantly associated with kidney function, AER, or measures of red blood cell count while urinary NAG was associated with parameters of glucose control and renal function.


CONCLUSIONS
Different urinary biomarkers may reflect distinct pathophysiological mechanisms of tubulointerstitial damage in early diabetic nephropathy: Urinary L-FABP could be a novel biomarker for chronic intrarenal ischaemia.
von Eynatten
M
M
Technical University Munich, Munich, Germany.
Baumann
M
M
Heemann
U
U
Zdunek
D
D
Hess
G
G
Nawroth
P P
PP
Bierhaus
A
A
Humpert
P M
PM
D000368:Aged; D000418:Albumins / Q000032:analysis; D000740:Anemia / Q000175:diagnosis / Q000453:epidemiology / Q000652:urine*; D015415:Biomarkers / Q000652:urine; D003404:Creatinine / Q000652:urine; D003924:Diabetes Mellitus, Type 2 / Q000150:complications / Q000652:urine*; D003928:Diabetic Nephropathies / Q000652:urine*; D004906:Erythrocyte Count; D050556:Fatty Acid-Binding Proteins / Q000652:urine*; D005260:Female; D005947:Glucose / Q000378:metabolism; D006454:Hemoglobins / Q000032:analysis; D000072596:Hepatitis A Virus Cellular Receptor 1; D006801:Humans; D007676:Kidney Failure, Chronic / Q000453:epidemiology / Q000652:urine*; D007677:Kidney Function Tests; D008297:Male; D008562:Membrane Glycoproteins / Q000652:urine*; D008875:Middle Aged; D015999:Multivariate Analysis; D009363:Neoplasm Proteins / Q000652:urine; D011991:Receptors, Virus
D000418:Albumins; D015415:Biomarkers; D050556:Fatty Acid-Binding Proteins; C491143:HAVCR1 protein, human; D006454:Hemoglobins; D000072596:Hepatitis A Virus Cellular Receptor 1; D008562:Membrane Glycoproteins; C117339:NBAS protein, human; D009363:Neoplasm Proteins; D011991:Receptors, Virus; D003404:Creatinine; D005947:Glucose