Table 1. Clinical and dietary characteristics by quartiles of measured net acid excretion.
| Quartile of Net acid excretion (mEq/d) | |||||
|---|---|---|---|---|---|
| Characteristic in N (%) or mean ± SD | 1 (<20.4) N=245 |
2 (20.4–30.7) N=243 |
3 (30.8–41.8) N=246 |
4 (≥41.9) N=246 |
P* |
| Demographics | |||||
| Age (years) | 59 ±11 | 59 ±11 | 58 ±12 | 56 ±10 | 0.02 |
| Female sex | 140 (57%) | 125 (51%) | 95 (39%) | 66 (27%) | <0.01 |
| Race | <0.01 | ||||
| Non-Hispanic white | 70 (29%) | 82 (34%) | 114 (46%) | 133 (54%) | |
| Non-Hispanic black | 128 (52%) | 117 (48%) | 95 (39%) | 85 (35%) | |
| Hispanic | 39 (16%) | 37 (15%) | 26 (11%) | 23 (9%) | |
| Other | 8 (3%) | 7 (3%) | 11 (4%) | 5 (2%) | |
| Medical History | |||||
| Diabetes | 116 (47%) | 113 (47%) | 132 (54%) | 136 (55%) | 0.13 |
| Cardiovascular disease | 88 (36%) | 70 (29%) | 67 (27%) | 87 (35%) | 0.08 |
| Exam and Laboratory | |||||
| Body mass index (kg/m2) | 29.9 ± 8.3 | 31.5 ± 7.6 | 33.5 ± 8.5 | 33.7 ± 7.2 | <0.01 |
| Body surface area (m2) | 1.9 ± 0.3 | 2.0 ± 0.3 | 2.1 ± 0.3 | 2.2 ± 0.3 | <0.01 |
| 24 hour urine creatinine (mg/d) | 991 ± 415 | 1163 ± 410 | 1412 ± 505 | 1756 ± 645 | <0.01 |
| eGFR (ml/min/1.73m2) | 41 ± 14 | 43 ± 15 | 43 ± 14 | 49 ± 15 | <0.01 |
| Urine albumin (mg/d)† | 61 (11, 376) | 70 (9, 607) | 74 (12, 507) | 66 (10, 615) | 0.63 |
| Serum bicarbonate (mEq/l) | 24.7 ± 3.3 | 24.3 ± 3.3 | 24.2 ± 3.3 | 24.3 ± 3.4 | 0.34 |
| Serum anion gap (mEq/l) | 10.1 ± 2.8 | 10.2 ± 3.1 | 10.1 ± 3.1 | 10.3 ± 3.2 | 0.82 |
| Serum potassium (meq/l) | 4.4 ± 0.5 | 4.3 ± 0.5 | 4.4 ± 0.6 | 4.2 ± 0.5 | <0.01 |
| Dietary | |||||
| Total energy intake (kcal/day)† | 1515 (1116, 2153) | 1512 (1142, 2217) | 1701 (1230, 2256) | 1815 (1379, 2409) | <0.01 |
| Total protein intake (g/day)† | 54 (37, 79) | 59 (42, 78) | 63 (49, 87) | 72 (55, 103) | <0.001 |
| % Protein intake from plant sources | 36% (28%, 45%) | 33% (27%, 40%) | 34% (25%, 42%) | 30% (23%, 37%) | <0.001 |
| Calculated protein intake [Maroni (g/day)]‡ | 46 (35, 56) | 55 (44, 67) | 66 (53, 78) | 82 (66, 101) | <0.001 |
| Ounces of lean meat/fish/poultry (per 2000 kcal) † | 3.4 (2.4, 5.0) | 3.9 (2.7, 5.2) | 4.2 (3.1, 5.7) | 4.7 (3.6, 6.3) | <0.01 |
| Servings of fruits and vegetables (per 2000 kcal)† | 8.0 (4.9, 10.4) | 7.5 (5.2, 10.4) | 7.0 (4.4, 9.4) | 6.5 (4.6, 8.8) | <0.01 |
| Net endogenous acid production- Frasetto equation (mEq/d)ǁ | 37.6 ± 14.0 | 38.0 ± 15.7 | 41.8 ± 15.4 | 46.1 ± 15.0 | <0.01 |
*
p-value from ANOVA,kruskal-wallis or Chi-squared test, as appropriate.
†
median (25th, 75th percentile)
‡
Protein intake is calculated from 24 hour urea nitrogen excretion using the Maroni equation
ǁ
Net endogenous acid production= -10.2 + 54.5*[protein intake (g/d)/potassium intake (mEq/d)]20