Chen et al reported an equation for estimating 24-hour urine protein excretion based off analysis of a spot urine specimen. The authors are Chang Gung University in Taiwan.
Parameters:
(1) spot urine protein to creatinine ratio in mg/mg
(2) sex
(3) age in years
(4) body weight in kilograms
(5) coefficient for CKD stage
urine protein to creatinine ratio =
= (urine protein in mg/dL) / (urine creatinine in mg/dL)
Parameter
Finding
Points
urine protein to creatinine ratio
0.814 * LOIG10(ratio)
sex
male
0.11
female
0
age
-0.004 * (age)
body weight
0.004 * (weight)
CKD stage
G0
0
G1
0.002 * 1 = 0.002
G2
0.002 * 2 = 0.004
G3a
0.002 * 3.1 = 0.0063
G3b
0.002 * 3.5 = 0.007
G4
0.002 * 4 = 0.008
G5
0.002 * 5 = 0.010
X =
= SUM(points for all of the parameters) - 0.018
24 hour urine protein in grams =
= 10^X
The equation is reasonably accurate up to 3 grams per day. Estimates at higher levels of proteinuria may be inaccurate.
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