Table 3.
Independent Predictors of Serum Bicarbonate and Anion Gap
| Characteristic | Serum Bicarbonate | Anion Gap | ||
|---|---|---|---|---|
|
| ||||
| Change (mEq/L) | P | Change (mEq/L) | P | |
| Age (per 10 years) | 0.14 (0.01 to 0.26) | 0.03 | −0.17 (−0.35 to 0.01) | 0.06 |
| Women | −1.28 (−1.61–−0.95) | <0.001 | 0.76 (0.33–1.19) | 0.001 |
| Race/Ethnicity | ||||
| Mexican American | −0.31 (−0.72–0.10) | 0.13 | 0.11 (−0.43–to 0.64) | 0.69 |
| Non-Hispanic Black | 0.10 (−0.28 to 0.48) | 0.60 | 0.10 (−0.41 to 0.61) | 0.69 |
| Other | −0.27 (−0.72 to 0.17) | 0.22 | 0.39 (−0.13 to 0.91) | 0.14 |
| Body-mass index (per 1 kg/m2) | −0.03 (−0.05 to −0.01) | 0.003 | 0.003 (−0.02 to 0.03) | 0.83 |
| Poverty (<100% poverty index) | −0.14 (−0.48 to 0.20) | 0.41 | 0.20 (−0.22 to 0.63) | 0.34 |
| Less than high-school diploma | −0.23 (−0.55 to 0.10) | 0.17 | 0.21 (−0.17 to 0.60) | 0.27 |
| Activity Level (MET-min/wk) | ||||
| < 500 | −0.13 (−0.48 to 0.21) | 0.44 | −0.07 (−0.53 to 0.39) | 0.76 |
| 500–2000 | −0.17 (−0.43 to 0.09) | 0.20 | 0.11 (−0.23 to 0.46) | 0.52 |
| > 2000 | −0.25 (−0.53 to 0.04) | 0.09 | 0.25 (−0.10 to 0.61) | 0.16 |
| Smoking | ||||
| Former | −0.11 (−0.33 to 0.12) | 0.35 | 0.11 (−0.20 to 0.42) | 0.48 |
| Current | −0.44 (−0.75 to −0.14) | 0.006 | 0.24 (−0.11 to 0.60) | 0.17 |
| Estimated NEAP (per 10 mEq/day) | −0.04 (−0.08 to 0.01) | 0.08 | 0.02 (−0.03 to 0.07) | 0.48 |
| Fasting length | to | to | ||
| 2–6 hours | −0.61 (−1.37 to 0.16) | 0.12 | 0.76 (−0.06 to 1.57) | 0.07 |
| > 6 hours | −0.69 (−1.32 to −0.06) | 0.03 | 0.67 (0.13 to 1.20) | 0.02 |
| Soft drink consumption | ||||
| 1 | −0.26 (−0.57 to 0.05) | 0.10 | 0.48 (0.06 to 0.90) | 0.03 |
| ≥ 2 | −0.30 (−0.58 to −0.02) | 0.04 | 0.60 (0.17 to 1.04) | 0.008 |
| Diuretic use | 0.94 (0.34 to 1.55) | 0.003 | −0.28 (−1.22 to 0.65) | 0.54 |
| Cholesterol-lowering medication | 0.13 (−0.59 to 0.86) | 0.71 | −0.24 (−1.19 to 0.69) | 0.60 |
| Diabetes Mellitus | −0.15 (−0.92 to 0.63) | 0.71 | 0.64 (−0.25 to 1.53) | 0.15 |
| Systolic BP (per 10 mmHg) | −0.16 (−0.25 to −0.07) | 0.001 | 0.22 (0.09 to 0.35) | 0.002 |
| eGFR | ||||
| 75–89 mL/min/1.73m2 | −0.08 (−0.33 to 0.16) | 0.49 | 0.07 (−0.25 to 0.40) | 0.65 |
| < 75 mL/min/1.73m2 | −0.52 (−1.23 to 0.18) | 0.14 | 0.45 (−0.55 to 1.45) | 0.37 |
| UACR > 30 mg/g (%) | −0.04 (−0.42 to 0.35) | 0.85 | 0.10 (−0.33 to 0.53) | 0.65 |
| Serum albumin (g/dL) | −0.33 (−1.01 to 0.35) | 0.33 | −0.50 (−1.31 to 0.32) | 0.22 |
| Serum sodium (mg/dL) | 0.44 (0.36 to 0.52) | <0.001 | …… | |
| Serum chloride (mg/dL) | −0.33 (−0.42 to −0.24) | <0.001 | …… | |
| Serum potassium (mg/dL) | 0.32 (−0.09 to 0.73) | 0.12 | −0.38 (−1.00 to 0.24) | 0.22 |
| Serum calcium (mg/dL) | 0.20 (−0.38 to 0.77) | 0.50 | 0.08 (−0.62 to 0.79) | 0.81 |
| Serum phosphate (mg/dL) | −0.34 (−0.50 to −0.18) | <0.001 | 0.52 (0.26 to 0.77) | <0.001 |
| Hemoglobin (g/dL) | −0.25 (−0.39 to −0.10) | 0.001 | 0.31 (0.11 to 0.52) | 0.003 |
| Total cholesterol (per 10 mg/dL) | −0.004 (−0.03 to 0.02) | 0.71 | 0.04 (0.01 to 0.07) | 0.01 |
| HDL cholesterol (per 10 mg/dL) | 0.08 (−0.02 to 0.17) | 0.10 | −0.04 (−0.14 to 0.07) | 0.49 |
| C-reactive protein | ||||
| 0.14–0.99 mg/dL | −0.06 (−0.25 to 0.14) | 0.57 | 0.29 (0.05 to 0.54) | 0.02 |
| ≥ 1.0 mg/dL | −0.18 (−0.61 to 0.24) | 0.39 | 0.73 (0.11 to 1.35) | 0.02 |
Abbreviations: MET, metabolic equivalent; BP, blood pressure; NEAP, net endogenous acid production; eGFR, estimated glomerular filtration rate; UACR, urinary albumin-creatinine ratio.
Multivariable model adjusted for all variables listed in the Table. Reference categories are non-Hispanic white for race/ethnicity; 0 Met-min/wk for activity level; non-smokers for smoking status; fasting length ≤2 hours; no soft drink consumption; eGFR ≥90 mL/min/1.73m2 for eGFR; and CRP <0.14 mg/dL