Table 1.
General and clinical characteristics according to the quartiles of serum ferritin
| Variables | Quartiles of serum ferritin (ng/mL) | ||||
| Quartile 1 (≤ 66.82) | Quartile 2 (66.83–100.78) | Quartile 3 (100.79–149.13) | Quartile 4 (> 149.13) | P for trend | |
| N | 1111 | 1110 | 1111 | 1110 | |
| Age (year) | 43.87 (0.512) | 42.10 (0.486) | 42.34 (0.459) | 42.31 (0.443) | 0.025 |
| SBP (mm Hg) | 119.58 (0.503) | 119.15 (0.553) | 119.26 (0.545) | 120.95 (0.522) | 0.083 |
| DBP (mm Hg) | 78.96 (0.411) | 79.41 (0.422) | 79.65 (0.392) | 81.58 (0.400) | < 0.001 |
| WC (cm) | 82.29 (0.311) | 83.97 (0.376) | 84.11 (0.338) | 86.05 (0.377) | < 0.001 |
| BMI (kg/m2) | 23.56 (0.106) | 24.14 (0.132) | 24.20 (0.116) | 24.82 (0.141) | < 0.001 |
| FBS (mg/dL) | 95.48 (0.613) | 96.63 (0.673) | 98.33 (0.893) | 101.28 (0.878) | < 0.001 |
| TC (mg/dL) | 184.81 (1.204) | 188.77 (1.180) | 191.67 (1.301) | 193.25 (1.396) | < 0.001 |
| Triglyceride (mg/dL) | 130.68 (3.151) | 143.87 (3.559) | 155.31 (4.443) | 182.03 (6.145) | < 0.001 |
| AST (IU/L) | 21.08 (0.245) | 21.89 (0.228) | 23.00 (0.292) | 24.38 (0.305) | < 0.001 |
| ALT (IU/L) | 20.72 (0.371) | 23.47 (0.433) | 24.78 (0.441) | 28.70 (0.548) | < 0.001 |
| Hb (g/dL) | 15.23 (0.039) | 15.45 (0.036) | 15.49 (0.033) | 15.60 (0.041) | < 0.001 |
| TIBC (μg/dL) | 320.41 (1.401) | 309.24 (1.316) | 306.42 (1.266) | 302.56 (1.539) | < 0.001 |
| Cr (mg/dL) | 0.95 (0.004) | 0.96 (0.005) | 0.96 (0.004) | 0.96 (0.004) | 0.011 |
| WBC (103/uL) | 6.20 (0.050) | 6.29 (0.054) | 6.31 (0.050) | 6.43 (0.051) | 0.001 |
| VitD (ng/mL) | 18.36 (0.249) | 18.35 (0.243) | 18.45 (0.243) | 18.13 (0.234) | 0.540 |
| Variables | Quartiles of serum ferritin (ng/mL) | ||||
| Quartile 1 (≤ 66.82) | Quartile 2 (66.83–100.78) | Quartile 3 (100.79–149.13) | Quartile 4 (> 149.13) | p-value | |
| Smoking status (%) | |||||
| Quit smoker or non-smoker | 681 (58.7) | 635 (52.5) | 586 (46.9) | 605 (50.7) | < 0.001 |
| Current smoker | 430 (41.3) | 473 (47.5) | 524 (53.1) | 504 (49.3) | |
| Alcohol intake (%) | |||||
| Less than once a month | 445 (37.1) | 339 (29.5) | 307 (28.3) | 258 (20.6) | < 0.001 |
| More than twice a month | 664 (62.9) | 764 (70.5) | 797 (71.7) | 845 (79.4) | |
| Hypertension (%) | |||||
| Hypertension (−) | 770 (74.8) | 760 (73.7) | 779 (73.0) | 723 (68.5) | 0.029 |
| Hypertension (+) | 341 (25.2) | 350 (26.3) | 332 (27.0) | 387 (31.5) | |
Data are presented as the mean (standard deviation), or numbers (percentages)
SBP systolic blood pressure, DBP diastolic blood pressure, WC waist circumference, BMI body mass index, FBS fasting blood sugar, TC total cholesterol, AST aspartate transaminase, ALT alanine transaminase, Hb hemoglobin, TIBC total iron-binding capacity, Cr creatinine, WBC white blood cell, VitD vitamin D