The association between serum zinc level and clinical features in patients with inflammatory bowel disease

Abstract

Zinc is an essential element and important for inflammatory bowel disease patients. Herein, we aimed to elucidate the correlation between serum zinc concentration and various parameters, especially the disease activity index and endoscopic scores, in these patients. We measured serum zinc concentrations in 37 patients with Crohn's disease and 64 with ulcerative colitis and retrospectively analyzed patient characteristics, blood test values, disease activity, and endoscopic scores. Hypozincemia (<80 ‍μg/dl) was observed in 45.9% and 29.7% of patients with Crohn's disease and ulcerative colitis, respectively. Serum zinc concentration showed a weak negative correlation with Crohn's Disease Activity Index and C-reactive protein levels in Crohn's disease patients, and a weak negative correlation with white blood cell count in ulcerative colitis patients. The zinc concentrations in ulcerative colitis patients were significantly lower in Mayo endoscopic sub-score grade 2 than in grades 0 and 1. The simple endoscopic score for Crohn's disease moderately correlated with zinc concentration. In addition, serum zinc concentration showed a moderate correlation with serum albumin and Onodera's prognostic nutritional index in both Crohn's disease and ulcerative colitis patients. Serum zinc concentration clearly correlated with inflammatory bowel disease activity, endoscopy scores, and immunonutritional parameters, suggesting the importance of monitoring zinc levels.

Keywords: Crohn’s disease; disease activity; hypozincemia; ulcerative colitis; zinc.

Fig. 1.

Distribution of serum zinc concentration in Crohn’s disease (CD) (A) and ulcerative colitis (UC) (B). Double arrow indicates the range of patients with hypozincemia (<80 ‍μg/dl).

Fig. 2.

Correlation between serum zinc concentration and patient age, disease duration, and body mass index (BMI) in patients with Crohn’s disease (CD) (A) and ulcerative colitis (UC) (B). Comparison of serum zinc concentration and disease distribution classified as ileal, ileocolic, and colic type in CD patients (C, D) and total colitis, left-sided colitis, and proctitis type in UC patients (E, F). The lower bar graphs (D, F) show the percentage of zinc levels divided into normal (≥80 ‍μg/dl, white color) and hypozincemia (<80 ‍μg/dl, gray color) in which zinc deficiency (<60 ‍μg/dl) is shown with hatched.

Fig. 3.

Correlation between serum zinc concentration and C-reactive protein (CRP) level and white blood cell (WBC) count in patients with Crohn’s disease (CD; A and C, respectively) and ulcerative colitis (UC; E and G, respectively). Each of the lower bar graphs (B, D, F, H) show the percentage of zinc levels divided into normal (≥80 ‍μg/dl, white color) and hypozincemia (<80 ‍μg/dl, gray color), in which zinc deficiency (<60 ‍μg/dl) is shown with hatched, while normal and high CRP levels or WBC count correspond to the respective upper scatter plots. Abnormal high CRP level and WBC count was defined as values >0.3 and ≥9,000, respectively.

Fig. 4.

Correlation of serum zinc concentration with disease activity and endoscopic score in patients with Crohn’s disease (CD) and ulcerative colitis (UC). For disease activity, Crohn’s Disease Activity Index (CDAI) and Lichtiger index were used for CD (A, B) and UC (C, D), respectively. The lower bar graphs (B, D) show the percentage of zinc levels divided into normal (≥80 ‍μg/dl, white color) and hypozincemia (<80 ‍μg/dl, gray color), in which zinc deficiency (<60 ‍μg/dl) is shown with hatched, for active and inactive. Disease activity according to the CDAI and Lichtiger index was defined as values ≥151 and ≥4, respectively. For endoscopic score, simple endoscopic score for Crohn’s disease (SES-CD) and Mayo endoscopic subscore (Mayo-ES) were used in CD patients (E) and UC patients (F), respectively. *p<0.05 (Tukey’s test).

Fig. 5.

Correlation between serum zinc concentration and serum albumin (Alb) and Onodera’s prognostic nutritional index (O-PNI) in patients with Crohn’s disease (CD, A and C, respectively) and ulcerative colitis (UC, B and D, respectively).