Table 1.
Population Characteristics of Adults Aged 25 Years and Older From the NHANES I and NHEFS Studies With Normal (≤45%) or Increased (>45%) Transferrin Saturation (TS) Levels and Low (≤18 mg) or High (>18 mg) Iron Uptake Levels
| Variable | Normal TS, Low Iron Intake n = 48,398,797 | Normal TS, High Iron Intake n = 9,720,794 | Increased TS, Low Iron Intake n = 3,994,430 | Increased TS, High Iron Intake n = 606,162 |
| Age, y | ||||
| 25–34 | 22.07 | 34.63 | 23.63 | 37.23 |
| 35–44 | 20.99 | 25.05 | 19.87 | 21.18 |
| 45–54 | 23.47 | 20.26 | 25.71 | 26.67 |
| 55–64 | 20.90 | 14.18 | 19.14 | 7.37 |
| >64 | 12.58 | 5.89 | 11.65 | 7.54 |
| Sex | ||||
| Male | 39.88 | 79.02 | 45.61 | 75.42 |
| Female | 60.12 | 20.98 | 54.39 | 24.58 |
| Race | ||||
| White | 90.35 | 91.58 | 94.46 | 93.58 |
| Black | 8.94 | 7.60 | 4.23 | 6.42 |
| Other | 0.71 | 0.82 | 1.31 | 0 |
| Ever smoker | ||||
| Yes | 60.70 | 76.21 | 66.21 | 87.39 |
| No | 39.30 | 23.79 | 33.79 | 12.61 |
| Body mass index, kg/m2 | ||||
| <30 | 83.00 | 85.27 | 90.01 | 99.56 |
| ≥30 | 17.00 | 14.73 | 9.99 | 0.44 |
NHANES = National Health and Nutrition Examination Survey; NHEFS = NHANES I Epidemiologic Follow-Up Study.