Table 3.

Adjusted urine acid excretion biomarkers during the control and alkali periods by CKD status.

Urine acid excretion marker	Non-CKD (n=6)			CKD (n=8)
	Control period	Alkali period	Net difference*	Control period	Alkali period	Net difference*
NAE, mEq/d	30.4 ± 13.1	25.0 ± 13.8	−5.4 (−14.5, 3.6)	26.7 ± 8.1	13.4 ± 12.7	−13.3 (−21.1, −5.5)a
pH	6.2 ± 0.5c	6.8 ± 0.3	0.6 (0.2, 1.0)a	5.7 ± 0.2c	6.6 ± 0.3	0.9 (0.6, 1.3)a
Ammonium, mEq/d	25.7 ± 8.0c	25.0 ± 8.5d	−0.7 (−4.5, 3.1)	16.1 ± 6.5c	11.3 ± 5.2d	−4.8 (−8.1, −1.5)a
Bicarbonate, mEq/d	5.6 ± 6.1	8.1 ± 7.7	2.5 (−2.3, 7.3)	0.9 ± 1.1	5.8 ± 5.5	4.9 (0.7, 9.0)b
Citrate, mg/d	689.1 ± 219.6c	698.3 ± 215.5	9.3 (−51.0, 69.5)	422.4 ± 195.7c	485.9 ± 248.2	63.6 (11.4, 115.7)b

Data are expressed as means ± standard deviations and β coefficients (95% confidence interval). Values are regressed to mean 24-hour urine creatinine. All participants completed two consecutive 24-hour urine collections at the end of the alkali and control periods except for one participant in the Non-CKD group who completed one 24-hour urine collection at the end of the control period. Significant alkali-by-CKD interaction, with P-interaction of <0.2 for NAE, ammonium, pH and citrate; therefore, the overall result was not presented. CKD, chronic kidney disease; NAE, net acid excretion. P-value for within-group net difference

^a≤0.01 and

^b<0.05. P-value for between-group difference

^c<0.05 and

^d<0.01.

^*Net difference in urine acidity markers was defined as the value at the end of the alkali period minus the value at the end of the control period.