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Open Access Research article

Inverse correlation between serum interleukin-6 and iron levels among Japanese adults: a cross-sectional study

Hiroko Nakagawa1*, Takashi Tamura1, Yoko Mitsuda1, Yasuyuki Goto1, Yoshikazu Kamiya2, Takaaki Kondo3, Kenji Wakai1 and Nobuyuki Hamajima4

Author Affiliations

1 Department of Preventive Medicine, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550, Japan

2 Department of Hematology and Oncology, National Hospital Organization, Higashi Nagoya National Hospital, Nagoya, Japan

3 Department of Pathophysiological Laboratory Sciences, Nagoya University Graduate School of Medicine, Nagoya, Japan

4 Department of Healthcare Administration, Nagoya University Graduate School of Medicine, Nagoya, Japan

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BMC Hematology 2014, 14:6  doi:10.1186/2052-1839-14-6

Published: 28 February 2014

Abstract

Background

Interleukin-6 (IL-6) is a multifunctional cytokine that is produced by many different cell types, and plays an important role in the regulation of inflammation, immune responses, the acute-phase response, and hematopoiesis. Previous laboratory and clinical studies have shown that IL-6 causes a significant decrease in serum iron levels. Therefore, we conducted an epidemiological study to examine the association between serum IL-6 and iron levels.

Methods

In total, 280 Japanese individuals aged 20–78 years were enrolled when they visited a clinic located in an urban area for Helicobacter pylori (H. pylori) infection tests and subsequent eradication; 65.3% were infected with H. pylori. Subjects with gastric cancer, idiopathic thrombocytopenia, or IL-6 > 10 pg/mL were excluded from the study. Serum iron and IL-6 levels were measured using the 2-nitroso-5-(N-propyl-3-sulfopropylamino) phenol method and chemiluminescence enzyme immunoassay, respectively.

Results

Geometric mean iron and IL-6 levels were 111.5 μg/dL and 1.77 pg/mL, respectively, for men, and 89.4 μg/dL and 1.55 pg/mL, respectively, for women. The logarithm of serum iron levels was negatively correlated with the logarithm of IL-6 levels in men (r = −0.19, p = 0.047), but not in women (r = −0.035, p = 0.65). Regression analysis, adjusted for sex, age, and H. pylori infection status, showed that the logarithm of serum iron levels was significantly associated with a decreased logarithm of IL-6 levels (β = −0.053, p = 0.041). The odds ratio for low serum iron levels adjusted for sex, age, and H. pylori infection status was 7.88 (95% CI 1.29–48.06) in those with an IL-6 level > 4 pg/mL.

Conclusion

Lower serum iron levels are significantly associated with higher serum IL-6 levels among Japanese adults.

Keywords:
Serum interleukin-6; Serum iron; Inflammation; Helicobacter pylori