Table 2.

Urinary sodium and potassium excretion and creatinine clearance rate in different age groups

Sex	Age group, years	n	Urinary Na excretion (mmol/24 h)	Urinary K excretion (mmol/24 h)	Na/K ratio	CCR (mL/min)	Salt intake (g/d)
Men	60–69	75	223.6 ± 18.2	70.1 ± 15.3	3.29 ± 1.56	153.6 ± 20.1	13.1 ± 1.1
	70–79	94	218.3 ± 19.1	68.0 ± 14.7	3.31 ± 1.33	151.2 ± 19.8	12.7 ± 1.1
	80–89	96	182.5 ± 20.7	57.3 ± 13.6	3.35 ± 1.26	133.4 ± 18.6	10.6 ± 1.2
	≥90	51	178.4 ± 17.8	47.6 ± 12.2	3.26 ± 1.80	103.5 ± 20.5	10.4 ± 1.0
	Subtotal	316	211.4 ± 19.5	60.6 ± 13.8	3.32 ± 1.72	134.5 ± 20.5	12.4 ± 1.1
Women	60–69	77	217.1 ± 19.3	68.2 ± 17.6	3.28 ± 2.06	150.1 ± 24.0	12.7 ± 1.5
	70–79	53	195.7 ± 22.4	65.6 ± 16.9	3.38 ± 1.83	150.3 ± 21.2	11.4 ± 1.4
	80–89	65	175.9 ± 23.2	60.3 ± 12.8	3.51 ± 1.41	137.8 ± 23.4	10.3 ± 1.1
	≥90	30	166.0 ± 19.9	45.9 ± 13.1	3.40 ± 1.21	119.6 ± 18.7	9.7 ± 1.6
	Subtotal	225	200.2 ± 17.6	59.5 ± 12.7	3.36 ± 1.81	138.5 ± 20.5	11.7 ± 1.0
Total	60–69	152	221.6 ± 31.1	68.3 ± 19.5	3.24 ± 1.93	151.2 ± 26.9	12.9 ± 1.8
	70–79	147	205.8 ± 27.7	66.2 ± 18.5	3.20 ± 1.71	150.7 ± 21.8	12.0 ± 1.6
	80–89	161	181.1 ± 19.8	58.9 ± 16.6	3.37 ± 1.62	135.9 ± 19.5	10.6 ± 1.2
	≥90	81	172.5 ± 18.2	47.7 ± 13.1	3.65 ± 1.80	101.0 ± 19.9	10.1 ± 1.1
	Subtotal	541	200.4 ± 19.1	59.6 ± 17.3	3.36 ± 1.91	138.5 ± 20.5	11.7 ± 1.1

Data are presented as mean ± standard deviation.

Na/K ratio, sodium/potassium ratio; CCR, creatinine clearance rate.

Salt intake was estimated as follows: urinary sodium (mmol/L) × 24-h urine volume (L) × 58.5 g.