Table 1.
Characteristics of CKD patients divided by TSAT and serum iron.
| Variable | All | Normal TSAT | Low TSAT | P value | ||
|---|---|---|---|---|---|---|
| Normal iron | Low iron | Normal iron | Low iron | |||
| TSAT (%) | ≧ 20 | ≧ 20 | < 20 | < 20 | ||
| Serum iron female (μg/dL) | ≧ 60 | < 60 | ≧ 60 | < 60 | ||
| Serum iron male (μg/dL) | ≧ 70 | < 70 | ≧ 70 | < 70 | ||
| Number of patients | 2500 | 1451 | 406 | 69 | 574 | |
| Demographics, medical history, and clinical parameters | ||||||
| Age (year) | 62.4 (14.5) | 61.8 (14.7) | 65.1 (13.4)* | 63.2 (12.6) | 61.9 (14.7) | < 0.001 |
| Sex (female) (%) | 899 (36.0%) | 467 (32.2%) | 118 (29.1%) | 48 (69.6%)* | 266 (46.3%)* | < 0.001 |
| Diabetes mellitus (%) | 1230 (49.2%) | 617 (42.5%) | 225 (55.4%)* | 42 (60.9%)* | 346 (60.3%)* | < 0.001 |
| Cardiovascular disease (%) | 553 (22.1%) | 287 (19.8%) | 106 (26.1%)* | 12 (17.4%)* | 148 (25.8%)* | 0.003 |
| Hypertension (%) | 1513 (60.5%) | 863 (59.5%) | 245 (60.3%) | 47 (68.1%) | 358 (62.4%) | 0.368 |
| Hyperuricemia (%) | 448 (17.9%) | 288 (19.8%) | 74 (18.2%) | 8 (11.6%)* | 78 (13.6%)* | 0.005 |
| Metabolic syndrome (%) | 1673 (66.9%) | 941 (64.9%) | 259 (63.8%) | 58 (84.1%)* | 415 (72.3%)* | < 0.001 |
| Malnutrition-inflammation (%) | 1159 (46.4%) | 553 (38.1%) | 285 (70.2%)* | 18 (26.1%)* | 303 (52.8%)* | < 0.001 |
| MAP | 99.4 (13.4) | 99.2 (13.1) | 99.0 (14.4) | 97.7 (11.7) | 100.3 (13.6) | 0.225 |
| BMI | 25.1 (4.0) | 25.2 (3.8) | 24.6 (4.1) | 26.3 (4.2) | 25.1 (4.4) | 0.004 |
| Renal function status | ||||||
| eGFR (ml/min/1.73 m2) | 35.2 (24.5–48.7) | 36.7 (26.1–49.7) | 28.9 (20.7–41.3)* | 37.0 (27.0–52.8) | 32.9 (22.6–46.2) | < 0.001 |
| UPCR (mg/g) | 691.8 (247–1797) | 585 (217–1446) | 1165 (354–2899) | 675 (195–1479) | 848 (281–2330) | < 0.001 |
| Laboratory data | ||||||
| Hemoglobin (g/dL) | 12.2 (2.2) | 12.7 (2.1) | 11.4 (2.1)* | 12.3 (1.9) | 11.5 (2.2)* | < 0.001 |
| Albumin (g/dL) | 3.9 (0.5) | 4.0 (0.5) | 3.7 (0.7)* | 4.1 (0.4) | 3.8 (0.5)* | < 0.001 |
| ALT (mg/dL) | 26.9 (24.4) | 28.0 (26.1) | 24.8 (25.4)* | 35.5 (29.8)* | 24.6 (17.6)* | < 0.001 |
| WBC (× 1,000 cells/μl) | 7.2 (2.3) | 6.9 (2.1) | 7.5 (2.3)* | 7.0 (2.5) | 7.6 (2.5)* | < 0.001 |
| CRP (mg/l) | 1.0 (0.3–4.7) | 0.8 (0.3–3.1) | 1.7 (0.5–8.1)* | 0.5 (0.2–2.3) | 1.4 (0.4–7.0)* | < 0.001 |
| Phosphorus (mg/dL) | 3.9 (0.8) | 3.8 (0.8) | 4.0 (0.9)* | 3.9 (0.6) | 4.0 (0.9)* | 0.003 |
| Calcium (mg/dL) | 9.2 (0.7) | 9.3 (0.6) | 9.1 (0.8)* | 9.4 (0.6)* | 9.3 (0.7) | < 0.001 |
| Bicarbonate (mEq/L) | 23.7 (3.7) | 24.0 (3.6) | 22.9 (4.0)* | 24.4 (3.2) | 23.6 (3.9)* | < 0.001 |
| Uric acid (mg/dL) | 7.6 (1.9) | 7.6 (1.9) | 7.8 (1.9) | 7.2 (1.7) | 7.5 (2.1) | 0.074 |
| Total cholesterol (mg/dL) | 194 (166–225) | 193 (167–223) | 192 (163–222) | 190 (167–223) | 197 (165–232)* | 0.397 |
| Triglyceride (mg/dL) | 127 (92–189) | 126 (92–183) | 124 (91–181) | 165 (90–223)* | 133 (95–208) | 0.032 |
| HbA1c (%) | 6.7 (1.7) | 6.4 (1.5) | 6.7 (1.8)* | 7.0 (1.7)* | 7.1 (2.0)* | < 0.001 |
Data were presented as mean (standard error), median (interquartile range), or count (percentage). P value column meant differences among groups (< 0.05 was significant).
*Meant significant difference (P < 0.05) compared with normal TSAT normal iron group in post hoc analysis. The significance of differences for normally-distributed continuous variables among groups was tested using one-way ANOVA with post hoc analysis by Fisher’s least significant difference test and, for non-normally-distributed continuous variables, it was tested using Kruskall–Wallis analysis with post hoc analysis by Dunn–Bonferroni method. The difference in the distribution of categorical variables among groups was tested using the Chi-square test with post hoc analysis by Bonferroni method.