The urine protein to creatinine ratio as a predictor of 24-hour urine protein excretion in type 1 diabetic patients with nephropathy. The Collaborative Study Group.
The purpose of this study was to determine the usefulness of a random urine specimen protein to creatinine (P/C) ratio in predicting 24-hour urine protein excretion (24 UP) in type 1 diabetic patients with overt nephropathy. Two hundred twenty-nine outpatient diabetic subjects enrolled in the Collaborative Study Group's multicenter clinical trial of "Angiotensin-Converting Enzyme Inhibition in Type 1 Diabetic Nephropathy" provided specimens for study, which encompassed a wide range of proteinuria (0.05 to 13.3 g/d). Twenty-four hour urine collections for total protein and creatinine (g/d) were obtained in the outpatient setting. This was followed shortly thereafter by an untimed single urine specimen for protein and creatinine (mg/dL). For longitudinal analysis, 33 patients provided two 24-hour urine collections with concomitant random urine specimens, separated by at least a 3-month period. Across the range of proteinuria that we studied, the log random urine P/C ratio correlated to log 24 UP (r = 0.90). The regression line was almost identical to the line of unity, which indicates that a patient's 24 U/P (in g/d) can be predicted directly from the random urine specimen P/C ratio (P/C = 24 UP in g/d). However, the standard deviations associated with these predictions were large, especially at the higher 24 UP values. Of the 33 patients who provided two time-separated specimens, the direction of change in P/C ratio was discordant with the direction of change in 24 UP in 14 of the 33 repeat specimens.(ABSTRACT TRUNCATED AT 250 WORDS)
Rodby
R A
RA
Department of Medicine, Rush-Presbyterian St Luke's Medical Center, Chicago, IL 60612, USA.
Rohde
R D
RD
Sharon
Z
Z
Pohl
M A
MA
Bain
R P
RP
Lewis
E J
EJ
D000328:Adult; D003404:Creatinine / Q000652:urine*; D003922:Diabetes Mellitus, Type 1 / Q000652:urine*; D003928:Diabetic Nephropathies / Q000652:urine*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011507:Proteinuria / Q000652:urine*
D003404:Creatinine