To rule out the effect of falsely elevated calcitriol levels due to secondary hyperparathyroidism associated with VD deficiency itself, the association of calcitriol concentrations and calcitriol/25-hydroxyvitamin D activation ratios with systemic CCL20 levels was evaluated in subsets of patients with Crohn’s disease, patients with ulcerative colitis, and HCs with sufficient 25-hydroxyvitamin D serum status [25-hydroxyvitamin D ≥ 20 ng/mL] using linear regression models50. Here, CCL20 is linked to ulcerative colitis.