Urinary liver-type fatty acid-binding protein: discrimination between IgA nephropathy and thin basement membrane nephropathy.
BACKGROUND
Microscopic hematuria without proteinuria is a common clinical finding in cases of immunoglobulin A (IgA) nephropathy and of thin basement membrane nephropathy. Liver-type fatty acid-binding protein (L-FABP) is expressed in renal proximal tubules and is reported to be a useful marker of the progression of chronic glomerulonephritis.


OBJECTIVE
To assess urinary L-FABP levels for differential diagnosis in patients with microscopic hematuria but without proteinuria.


METHODS
This was a multi-center retrospective study. Thirty adult patients who underwent renal biopsy for microscopic hematuria and 20 healthy adult volunteers were included in this study. Urinary L-FABP levels were measured by enzyme-linked immunosorbent assay and compared, particularly between those diagnosed with IgA nephropathy and those diagnosed with thin basement membrane nephropathy.


RESULTS
Twelve (40%) patients had IgA nephropathy, 6 (20%) had thin basement membrane nephropathy and 12 (40%) had normal biopsy findings. The urinary L-FABP level was significantly higher in patients with IgA nephropathy (38.4 +/- 26.8 microg/g Cr) than in healthy subjects (5.8 +/- 4.0 microg/g Cr) (p < 0.01); however, the level in patients with thin basement membrane nephropathy or normal biopsy results was comparable to that in healthy subjects. Follow-up data were available for 11 of the 12 patients with IgA nephropathy who initially had no proteinuria. After 24 months, 4 of the 11 were found to have proteinuria, and the urinary L-FABP level had increased from 40.6 +/- 30.5 microg/g Cr to 58.8 +/- 40.5 microg/g Cr (p < 0.01).


CONCLUSIONS
Our data suggest that the urinary L-FABP level can be used to discriminate between IgA nephropathy and thin basement membrane nephropathy in patients with microscopic hematuria.
Nakamura
Tsukasa
T
Department of Medicine, Shinmatsudo Central General Hospital, Chiba, Japan.
Sugaya
Takeshi
T
Ebihara
Isao
I
Koide
Hikaru
H
D000328:Adult; D003937:Diagnosis, Differential; D050556:Fatty Acid-Binding Proteins / Q000652:urine*; D005260:Female; D005922:Glomerulonephritis, IGA / Q000175:diagnosis* / Q000652:urine; D015433:Glomerulonephritis, Membranous / Q000175:diagnosis* / Q000652:urine; D006801:Humans; D008297:Male; D008875:Middle Aged; D009994:Osmolar Concentration; D012189:Retrospective Studies
C493319:FABP1 protein, human; D050556:Fatty Acid-Binding Proteins