Table 7.

Precision of GFR as a function of sampling duration^a

Sampling Duration	Mean GFR CV (%)	95% CI	Difference from 10-h GFR	95% CI of Difference	P
10 h	1.67	1.38 to 2.01
9 h	1.81	1.50 to 2.18	1.09	0.93 to 1.27	>0.2
8 h	2.06	1.71 to 2.48	1.24	1.06 to 1.44	0.007
7 h	2.38	1.98 to 2.87	1.43	1.23 to 1.67	<0.001
6 h	2.85	2.37 to 3.43	1.71	1.47 to 1.99	<0.001
5 h	3.48	2.89 to 4.19	2.09	1.79 to 2.44	<0.001
4 h	4.31	3.58 to 5.19	2.59	2.22 to 3.02	<0.001
3 h	4.86	4.01 to 5.89	2.91	2.48 to 3.42	<0.001
2.5 h	6.11	5.08 to 7.36	3.67	3.15 to 4.28	<0.001
2 h	7.07	5.87 to 8.51	4.24	3.63 to 4.95	<0.001

^aMean GFR coefficient of variation (CV) calculated using a nominal mixed model with log-transformed CV using maximal likelihood estimates.