Table 2 Correlation coefficients and univariate linear regression analysis of each variable to the hemoglobin levels

Sex, female

-1.43 (-1.99, -0.88)

 < 0.001

Age (year)

-0.46

-0.06 (-0.08, -0.05)

 < 0.001

Body mass index

0.21

0.1 (0.04, 0.16)

0.001

Smoking

0.86 (0.34, 1.39)

0.001

Cancer

-1.38 (-2.18, -0.59)

0.001

Diabetes

-0.53 (-1.09, 0.04)

0.07

Bone fracture

-2.2 (-3.58, -0.82)

0.02

Gastrointestinal bleeding

0.93 (-2.31, 4.17)

0.573

eGFR (mL/min/1.73 m²)

0.62

0.07(0.05, 0.08)

 < 0.001

Urine protein (g/gCr)

-0.37

-0.19 (-0.27, -0.12)

 < 0.001

Albumin (g/dL)

0.5

1.45 (1.11, 1.84)

 < 0.001

Calcium (mg/dL)

0.47

1.74 (1.35, 2.13)

 < 0.001

Phosphate (mg/dL)

-0.44

-1.45 (-1.77, -1.13)

 < 0.001

Serum iron (μg/dL)

0.38

0.03 (0.02, 0.03)

 < 0.001

Total iron-binding capacity (μg/dL)

0.4

0.01 (0.01, 0.02)

 < 0.001

Ferritin (ng/mL)

-0.12

-0.002 (-0.003, -0.001)

 < 0.001

C-reactive protein (mg/dL)

-0.13

-0.15 (-0.3, -0.01)

0.034

White blood cell (× 1,000/μL)

-0.04

-0.1 (-0.21, 0.02)

0.093

Reticulocytes (%)

-0.15

-0.91 (-1.5, -0.32)

0.003