Table 1. The patients' demographic and clinical characteristics.
| Age, yrs, median (IQR) | 62 (47.8–68) |
| Female, n (%) | 58 (82.9) |
| Diagnosis, n (%): | |
| RA | 43 (61.4) |
| SLE | 9 (12.9) |
| Mixed connective tissue disease | 5 (7.1) |
| Others | 13 (18.6) |
| Disease duration, yrs, median (IQR) | 11 (6–18) |
| BMI, kg/m2, median (IQR) | 21.6 (19.9–24.4) |
| Smoker, n (%) | 10 (14.3) |
| Sleeping pills, n (%) | 10 (14.3) |
| Oral iron preparation, n (%) * | 1 (1.5) |
| Vitamin D preparations, n (%) * | 14 (20.6) |
| Antipsychotic drugs, n (%) * | 1 (1.5) |
| Laboratory data, median (IQR): | |
| Hemoglobin, g/dl | 12.8 (11.6–14.1) |
| BUN, mg/dl | 14.0 (11.0–17.0) |
| Creatinine, mg/dl | 0.69 (0.60–0.80) |
| eGFR, ml/min/1.73m2 | 74.3 (58.4–85.2) |
| Total protein, g/dl | 7.50 (7.18–8.82) |
| Albumin, g/dl | 4.15 (3.90–4.43) |
| Ferritin, ng/ml | 55.0 (20.0–99.0) |
| Iron, μg/dl | 77.5 (54.0–118) |
| UIBC, μg/dl | 238 (200–303) |
| TSAT, % | 25.3 (14.6–38.2) |
| ESR, mm/hr | 12.0 (8.00–24.0) |
| CRP, mg/dl | 0.08 (0.03–0.20) |
| Up/Ucr, g/g▪Cr | 0.08 (0.05–0.15) |
*A total of 68 patients were evaluated. BMI: body mass index, BUN: blood urea nitrogen, CRP: C-reactive protein, eGFR: estimated glomerular filtration rate, ESR: erythrocyte sedimentation rate, IQR: interquartile range, RA: rheumatoid arthritis, SLE: systemic lupus erythematosus, TSAT: transferrin saturation, UIBC: Unsaturated iron binding capacity, Up/Ucr: urine protein/creatinine ratio.