Comparison between 24-h proteinuria, urinary protein/creatinine ratio and dipstick test in patients with nephropathy: patterns of proteinuria in dipstick-negative patients.
OBJECTIVE
Three main tests are commonly employed for the measurement of proteinuria: the dipstick test, the urinary protein/creatinine ratio (P/C) and the 24-h urine collection. The aim of this study was to evaluate the correlation between these methods, comparing linear regression and ROC curve data.


METHODS
A total of 297 consecutive outpatients with different renal diseases were included in the study. Twenty-four-hour proteinuria was considered the reference test.


RESULTS
A high degree of correlation was observed between all the tests (p<0.0001), the highest regression coefficient being between 24-h proteinuria and P/C (R=0.82), and the lowest between P/C and the dipstick test (R=0.72). The dipstick test failed to detect pathological proteinuria in 94 patients (31.6%). Therefore, in these subjects, the patterns of proteinuria were assessed by immunofixation and sodium dodecyl sulphate (SDS) electrophoresis.


CONCLUSIONS
Our data strongly support the use of urinary P/C for the detection of proteinuria, at least in nephrology units, where the prevalence of proteinuria is likely to be high.
Gai
M
M
Laboratory of Nephrology, Nephrology Unit, Department of Internal Medicine, University of Turin - Molinette Hospital, Turin, Italy. massimogai@katamail.com
Motta
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D
Giunti
S
S
Fop
F
F
Masini
S
S
Mezza
E
E
Segoloni
G P
GP
Lanfranco
G
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D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003404:Creatinine / Q000652:urine*; D006801:Humans; D007674:Kidney Diseases / Q000175:diagnosis* / Q000652:urine; D016014:Linear Models; D008875:Middle Aged; D011507:Proteinuria / Q000175:diagnosis* / Q000209:etiology / Q000652:urine; D012372:ROC Curve; D011934:Reagent Strips; D012016:Reference Values; D013997:Time Factors
D011934:Reagent Strips; D003404:Creatinine