Table 2 Correlations between serum iron, ferritin, and hepcidin levels and other parameters.

From: Serum hepcidin level, iron metabolism and osteoporosis in patients with rheumatoid arthritis

 

Correlation coefficients

Adjusted correlation coefficients*

Fe

Ferritin

Log(hep + 1)

Fe

Ferritin

Log(hep + 1)

Serum iron

1.000

0.318

0.307

1.000

0.251

0.401

 

(<0.001)

(<0.001)

 

(<0.001)

(<0.001)

Serum ferritin

0.318

1.000

0.816

0.251

1.000

0.657

(<0.001)

 

(<0.001)

(<0.001)

 

(<0.001)

Log(hep + 1)

0.307

0.816

1.000

0.401

0.657

1.000

(<0.001)

(<0.001)

 

(<0.001)

(<0.001)

 

Age

−0.161

0.092

0.072

—

—

—

(0.009)

(0.137)

(0.249)

Body mass index

−0.021

−0.011

−0.024

—

—

—

(0.732)

(0.856)

(0.697)

Disease duration

−0.050

−0.042

−0.023

0.044

0.047

0.057

(0.416)

(0.494)

(0.707)

(0.489)

(0.460)

(0.370)

eGFR

0.055

0.002

0.004

—

—

—

(0.378)

(0.980)

(0.946)

Red blood cell

0.024

−0.121

−0.123

−0.006

−0.139

−0.101

(0.694)

(0.050)

(0.047)

(0.922)

(0.028)

(0.110)

Hemoglobin

0.400

0.196

0.125

0.420

0.127

0.243

(<0.001)

(0.001)

(0.043)

(<0.001)

(0.045)

(<0.001)

Hematocrit

0.305

0.120

0.054

0.318

0.060

0.138

(<0.001)

(0.052)

(0.383)

(<0.001)

(0.347)

(0.029)

Platelet

−0.241

−0.173

−0.172

−0.186

−0.064

−0.203

(<0.001)

(0.005)

(0.005)

(0.003)

(0.315)

(0.001)

UIBC

−0.517

−0.707

−0.708

−0.646

−0.499

−0.669

(<0.001)

(<0.001)

(<0.001)

(<0.001)

(<0.001)

(<0.001)

DAS28-ESR

−0.316

0.109

0.100

−0.236

0.184

0.030

(<0.001)

(0.079)

(0.108)

(<0.001)

(0.003)

(0.633)

DAS28-CRP

−0.223

0.151

0.133

−0.100

0.140

0.091

(<0.001)

(0.014)

(0.032)

(0.114)

(0.026)

(0.152)

SDAI

−0.175

0.107

0.093

−0.100

0.176

0.034

(0.004)

(0.083)

(0.132)

(0.114)

(0.005)

(0.588)

CDAI

−0.148

0.094

0.068

−0.095

0.172

0.034

(0.016)

(0.131)

(0.273)

(0.133)

(0.06)

(0.596)

HAQ-DI

−0.167

−0.068

−0.047

−0.138

0.005

−0.117

(0.007)

(0.281)

(0.451)

(0.031)

(0.933)

(0.068)

Rheumatoid factor

0.014

0.061

0.029

0.003

0.028

0.005

(0.823)

(0.324)

(0.636)

(0.960)

(0.665)

(0.940)

ESR

−0.344

0.112

0.143

−0.178

0.178

0.075

(<0.001)

(0.070)

(0.021)

(0.005)

(0.005)

(0.241)

CRP

−0.235

0.219

0.257

—

—

—

(<0.001)

(<0.001)

(<0.001)

MMP-3

−0.206

0.051

−0.005

−0.053

0.187

−0.010

(0.001)

(0.412)

(0.930)

(0.402)

(0.003)

(0.874)

Daily PSL dose

−0.197

−0.049

−0.163

−0.320

0.052

−0.115

(0.001)

(0.433)

(0.008)

(0.617)

(0.413)

(0.058)

Weekly MTX dose

0.004

0.028

−0.056

−0.043

0.120

−0.0r06

(0.954)

(0.655)

(0.371)

(0.505)

(0.058)

(0.930)

Serum bone Alkaline phosphatase

−0.055

−0.003

−0.001

0.098

−0.024

−0.034

(0.376)

(0.957)

(0.986)

(0.122)

(0.710)

(0.588)

Serum TRACP-5b

−0.130

−0.008

−0.018

−0.0749

−0.074

−0.053

(0.035)

(0.894)

(0.777)

(0.227)

(0.244)

(0.405)

Serum adjusted calcium

0.013

0.086

0.071

−0.007

0.094

0.056

(0.830)

(0.165)

(0.249)

(0.910)

(0.139)

(0.378)

Serum phosphate

0.000

−0.021

0.063

−0.043

0.011

0.083

(0.998)

(0.730)

(0.310)

(0.497)

(0.861)

(0.193)

Serum 25(OH)D

0.046

0.250

0.193

0.042

0.200

0.202

(0.461)

(<0.001)

(0.002)

(0.510)

(0.001)

(0.001)

Serum FGF 23

0.009

0.040

−0.019

0.089

0.108

0.029

(0.889)

(0.523)

(0.763)

(0.160)

(0.089)

(0.644)

Femoral T score

0.230

0.006

−0.038

0.127

0.022

0.002

(<0.001)

(0.919)

(0.543)

(0.045)

(0.726)

(0.973)

Femoral Z score

0.150

0.067

0.044

0.126

0.041

0.044

(0.015)

(0.279)

(0.479)

(0.048)

(0.516)

(0.487)

Lumbar T score

0.067

−0.044

−0.110

−0.047

0.028

−0.072

(0.283)

(0.480)

(0.076)

(0.459)

(0.658)

(0.3257)

Lumbar Z score

0.004

−0.002

−0.051

−0.055

0.039

−0.043

(0.953)

(0.973)

(0.410)

(0.389)

(0.188)

(0.501)

Annual change of femoral T score

0.071

−0.104

−0.031

0.001

−0.132

−0.021

0.284

0.115

0.640

(0.989)

(0.050)

(0.762)

Annual change of lumbar T score

0.046

0.135

0.146

0.011

0.086

0.151

0.486

0.041

0.026

(0.869)

(0.206)

(0.026)

  1. *Adjusted for age, sex, BMI, eGFR, CRP, PSL use, bDMARD use, anti-resorption drug use, teriparatide use, and iron agent use.
  2. eGFR, estimated glomerular filtration rate; UIBC, unsaturated iron binding capacity; DAS28, disease activity scores in 28 joints; ESR, erythrocyte sedimentation rate; CRP, C-reactive protein; SDAI, simplified disease activity index; CDAI, clinical disease activity index; HAQ-DI, health assessment questionnaire without disability index; MMP-3, matrix metalloprotease 3; PSL, prednisolone; MTX, methotrexate; TRACP-5b, tartrate-resistant acid phosphatase-5b; 25(OH)D, 25-hydroxy vitamin D; FGF23, fibroblast growth factor 23.
  3. Annual change of T score was evaluated in 231 patients and the mean observational period was 2.0 ± 0.33 years (0.63–3.25).
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