Serum C-reactive Protein and Thioredoxin Levels in Subjects with Mildly Reduced Glomerular Filtration Rate

Shoko Tsuchikura; Tetsuo Shoji; Naoko Shimomura; Ryusuke Kakiya; Masanori Emoto; Hidenori Koyama; Eiji Ishimura; Masaaki Inaba; Yoshiki Nishizawa

Disclosures

BMC Nephrology. 2010;11:7 

In This Article

Results

eGFR and CRP

Figure 2 shows the relationship between eGFR and CRP. When compared between those with normal eGFR and those with mildly reduced eGFR, the median CRP level was significantly higher in the group with mildly reduced eGFR. CRP was inversely correlated with eGFR in the total subjects.

Figure 2.

Relationship between eGFR with CRP. Mann-Whitney Utest was used for comparison between median levels. Correlation was evaluated by Spearman's rank correlation method. Horizontal bars indicate 10th, 25th, 50th (median), 75th, and 90th percentile levels. Abbreviations: r, correlation coefficient; eGFR, estimated glomerular filtration rate; CRP, C-reactive protein.

eGFR and TRX

Figure 3 shows the relationship between eGFR and TRX. The median TRX level was significantly higher in the group with reduced eGFR. TRX was inversely correlated with eGFR in the total subjects.

Figure 3.

Relationship between eGFR with TRX. Mann-Whitney Utest was used for comparison between median levels. Correlation was evaluated by Spearman's rank correlation method. Horizontal bars indicate 10th, 25th, 50th (median), 75th, and 90th percentile levels. Abbreviations: r, correlation coefficient; eGFR, estimated glomerular filtration rate; TRX, thioredoxin.

Other Factors Correlating with CRP and TRX Levels

We examined other factors that may affect the levels of CRP and TRX (Table 2). CRP was positively correlated with age, BMI, systolic BP, non-HDL-C levels, and glucose levels, whereas CRP inversely correlated with HDL-C. TRX was positively correlated with age, BMI, and systolic BP, and inversely with HDL-C. TRX showed no significant correlation with plasma glucose or non-HDL-C. CRP and TRX showed a significant positive correlation.

Correlations between eGFR and other Clinical Variables

As shown in Table 3, eGFR was significantly associated with age, sex, BMI, systolic BP, non-HDL-C, HDL-C, and smoking status, but not with glucose level.

Independent Associations of eGFR with CRP

Because CRP and TRX showed significant correlations with other clinical parameters, multiple regression models were employed to examine whether eGFR had significant associations with CRP and TRX independent of these possible confounders. As shown in Table 4, eGFR showed an inverse association with CRP in model 1 in which no adjustment was done. In model 2, the association between eGFR and CRP was again significant after adjustment for age and sex. In models 3 and 4, the association between eGFR and CRP remained significant even after further adjustment for smoking status or glucose level. However, the association between eGFR and CRP was not significant when adjusted for BMI, SBP, Non-HDL-C, HDL-C, or TRX, in addition to age and sex.

Independent Associations of eGFR with TRX

As shown in Table 5, eGFR showed an inverse association with TRX in model 1 in which no adjustment was done. In model 2, the association between eGFR and TRX was again significant after adjustment for age and sex. In models 3 through 8, the association between eGFR and TRX remained significant even after further adjustment for BMI, SBP, Non-HDL-C, HDL-C, smoking status, or glucose. However, the association between eGFR and TRX was not significant when adjusted for CRP in addition to age and sex.

Multiple Regression Models to Simultaneously Adjust for Potential Confounders

To further investigate the eGFR-CRP and the eGFR-TRX links, we included all potential confounders simultaneously in multiple regression models (Table 6). CRP showed significant and independent associations with systolic BP (positively), non-HDL-C (positively), and HDL-C (inversely), but not with eGFR (P = 0.16). TRX showed a significant association with male sex, and trend of association with eGFR (P = 0.06) and systolic BP (P = 0.08) at borderline significance.

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