Creatinine clearance, cystatin C, beta2-microglobulin and TATI as markers of renal function in patients with proteinuria.
BACKGROUND
Proteinuria is a risk factor for end-stage renal disease (ESRD). Creatinine clearance (CrCl) is usually used as a marker to monitor the progression of ESRD, while cystatin C (CYST) has also been considered as a marker of renal function. Tumor-associated trypsin inhibitor (TATI) has been shown to be a promising marker of renal function. The aim of this study was to examine the relationship between CrCl, CYST, ß(2)-microglobulin (B2M) and TATI, with glomerular filtration rate (GFR) in patients with different levels of proteinuria.


METHODS
Seventy-one patients (37 males, 34 females, mean age 53 ± 15 years) were included in the study. GFR was measured by the bladder cumulative method using (99m)Tc-DTPA. Blood levels of CYST, B2M and TATI were also measured. CrCl and proteinuria were determined by 24-hour urine collection. Statistical analysis was performed with multivariate analysis.


RESULTS
The results are expressed as the ratio to GFR of CrCl and reciprocals of CYST (100/CYST), B2M (100/B2M) and TATI (100/TATI). The ratio CrCl/GFR increased from 1.41 in patients with proteinuria <1 g/day, to 1.66 (p<0.05) in those with proteinuria >3 g/day. The ratio 100/CYST/GFR was 1.67 and 2.28 (p<0.05), 100/B2M/GFR 0.90 and 0.69 and 100/TATI/GFR 0.14 and 0.19, respectively. Multivariate analysis demonstrated that ClCr/GFR as well as 100/CYST/GFR was independently related to the degree of proteinuria.


CONCLUSIONS
CrCl and CYST overestimate GFR in patients with heavy proteinuria, while the ratios 100/TATI and 100/B2M with GFR do not significantly change. The direct measurement of GFR still remains the best method to assess the progression of renal damage in patients with heavy proteinuria.
Nephrology Unit, Department of Internal Medicine, University of Pisa, Pisa, Italy. g.tramonti@med.unipi.it
Gianfranco
G
Tramonti
Ilaria
I
Cipollini
Carmela
C
Annichiarico
Paolo
P
Lorusso
Erica
E
Panicucci
Giuliano
G
Mariani
Giuliano
G
Barsotti
D000293:Adolescent; D000328:Adult; D000368:Aged; D015415:Biomarkers / Q000097:blood / Q000652:urine; D002352:Carrier Proteins / Q000097:blood*; D003404:Creatinine / Q000097:blood* / Q000652:urine; D055316:Cystatin C / Q000097:blood*; D018450:Disease Progression; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D007668:Kidney / Q000378:metabolism* / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D008954:Models, Biological; D015999:Multivariate Analysis; D011237:Predictive Value of Tests; D011379:Prognosis; D011507:Proteinuria / Q000097:blood* / Q000175:diagnosis / Q000503:physiopathology / Q000652:urine; D012044:Regression Analysis; D012720:Severity of Illness Index; D014359:Trypsin Inhibitor, Kazal Pancreatic; D055815:Young Adult; D001613:beta 2-Microglobulin / Q000097:blood*
D015415:Biomarkers; C525030:CST3 protein, human; D002352:Carrier Proteins; D055316:Cystatin C; C486642:SPINK1 protein, human; D001613:beta 2-Microglobulin; D014359:Trypsin Inhibitor, Kazal Pancreatic; D003404:Creatinine