Table 1.
Participant Characteristics by Quartiles of Full Anion Gap in 11,957 participants of NHANES 1999–2004
| Full Anion Gap (mEq/L) | |||||
|---|---|---|---|---|---|
| Characteristic | < 3.62 | 3.62 – 5.35 | 5.36 – 7.23 | > 7.23 | P |
| Number | 2783 | 3044 | 3033 | 3097 | |
| Age (years) | 44.1 (0.3) | 46.1 (0.5) | 46.6 (0.5) | 47.9 (0.5) | <0.001 |
| Women (%) | 47.1 (1.0) | 51.4 (1.3) | 51.9 (1.0) | 52.6 (1.0) | <0.001 |
| Race/Ethnicity (%) | 0.46 | ||||
| Non-Hispanic White | 72.6 (2.1) | 72.5 (2.0) | 71.9 (2.4) | 72.6 (2.7) | |
| Mexican American | 7.8 (1.1) | 7.7 (1.1) | 7.0 (1.1) | 6.5 (1.3) | |
| Non-Hispanic Black | 9.6 (1.1) | 11.7 (1.2) | 10.1 (1.0) | 9.3 (1.8) | |
| Body-mass index (kg/m2) | <0.001 | ||||
| < 20 | 5.8 (0.5) | 5.3 (0.6) | 5.0 (0.6) | 5.1 (0.5) | |
| 20 – 25 | 34.2 (1.3) | 29.6 (0.9) | 28.7 (1.1) | 24.0 (1.1) | |
| 25 – 29 | 36.0 (0.9) | 34.2 (1.2) | 35.2 (1.4) | 34.0 (1.0) | |
| 30 – 35 | 15.7 (0.7) | 19.7 (1.0) | 18.5 (0.8) | 20.1 (0.8) | |
| > 35 | 8.2 (0.7) | 11.3 (0.9) | 12.5 (0.9) | 16.7 (0.9) | |
| Less than high-school diploma (%) | 16.6 (1.2) | 18.5 (0.9) | 22.0 (1.0) | 23.1 (1.2) | <0.001 |
| Activity Level (MET-min/wk, %) | <0.001 | ||||
| 0 | 12.7 (0.8) | 15.0 (0.8) | 17.8 (0.9) | 20.7 (1.7) | |
| < 500 | 20.8 (1.1) | 22.8 (0.8) | 20.1 (1.2) | 19.9 (0.9) | |
| 500 – 2000 | 37.0 (1.1) | 37.3 (0.9) | 34.3 (1.1) | 32.0 (1.3) | |
| > 2000 | 29.5 (1.2) | 24.9 (1.2) | 27.9 (1.3) | 27.4 (1.6) | |
| Smoking (%) | 0.13 | ||||
| Never | 53.1 (1.1) | 50.4 (1.2) | 47.6 (1.3) | 48.6 (2.4) | |
| Former | 24.5 (1.1) | 24.3 (0.9) | 26.0 (1.1) | 26.0 (1.4) | |
| Current | 22.4 (1.3) | 25.3 (1.1) | 26.4 (1.2) | 25.4 (1.4) | |
| Hypertension (%) | 32.6 (1.3) | 39.3 (1.3) | 41.5 (1.2) | 47.2 (1.6) | <0.001 |
| Diabetes mellitus (%) | 4.0 (0.5) | 6.4 (0.7) | 8.2 (0.6) | 9.9 (0.7) | <0.001 |
| Cardiovascular disease (%) | 5.3 (0.6) | 8.5 (0.8) | 9.2 (0.7) | 10.7 (0.7) | <0.001 |
| eGFR (mL/min/1.73m2) | <0.001 | ||||
| 15 – 59 | 3.7 (0.4) | 5.7 (0.6) | 6.7 (0.5) | 9.2 (0.6) | |
| 60 – 89 | 34.9 (1.4) | 34.7 (1.4) | 35.9 (1.2) | 35.4 (0.9) | |
| 90 – 119 | 50.7 (1.3) | 49.4 (1.5) | 48.0 (1.3) | 46.7 (1.2) | |
| ≥ 120 | 10.6 (0.8) | 10.2 (0.7) | 9.4 (0.7) | 8.8 (0.8) | |
| UACR > 30 mg/g (%) | 5.8 (0.6) | 8.7 (0.7) | 9.6 (0.6) | 12.9 (0.8) | <0.001 |
| Hemoglobin (g/dL) | 14.49 (0.05) | 14.44 (0.06) | 14.55 (0.05) | 14.64 (0.07) | 0.02 |
| Serum bicarbonate (mEq/L) | 25.5 (0.1) | 24.6 (0.1) | 23.8 (0.1) | 22.6 (0.1) | <0.001 |
| Serum albumin (g/dL) | 4.40 (0.01) | 4.32 (0.01) | 4.34 (0.01) | 4.34 (0.01) | 0.03 |
| Serum calcium (mg/dL) | 9.49 (0.02) | 9.49 (0.01) | 9.47 (0.02) | 9.49 (0.02) | 0.61 |
| Serum phosphate (mg/dL) | 3.70 (0.02) | 3.71 (0.01) | 3.63 (0.02) | 3.59 (0.02) | <0.001 |
Abbreviations: MET, metabolic equivalent; eGFR, estimated glomerular filtration rate; UACR, urinary albumin-creatinine ratio.
Data are expressed as mean (SE) or percent (SE).