Table 3. Reference intervals of serum cystatin C in young and old subjects.

	<60 y				≥60 y
	n	Reference interval	Mean	Standard deviation	n	Reference interval	Mean	Standard deviation
G1	218	0.56–1.27	0.84	0.18	20	0.71–1.38	0.99*	0.17
G2	223	0.72–1.51	1.04	0.21	136	0.83–1.67	1.18*	0.22
G3a	45	0.98–2.61	1.59	0.44	61	1.02–2.61	1.64	0.43
G3b	22	1.57–4.01	2.50	0.60	42	1.32–4.48	2.43	0.87
G4-5	8	1.80–10.49	4.76	1.51	25	1.95–6.11	3.59	0.84

^* P<0.05 compared with the young.