GPT and vitamin D deficiency: Table 1 presents the clinical and biochemical characteristics of patients with and without a severe vitamin D deficiency (< 25 vs. ≥ 25 nmol/L). Serum levels of ALT (166 ± 29 vs. 83 ± 5, p < 0.001), bilirubin (116 ± 15 vs. 36 ± 3, p < 0.001), IgG (1.3 ± 0.4 vs. 0.6 ± 0.1, p = 0.008), INR (1.3 ± 0.04 vs. 1.2 ± 0.02, p = 0.005), and Mayo Score (1.40 ± 0.2 vs. 0.53 ± 0.1, p < 0.001) were significantly higher in patients with PSC and a severe vitamin D deficiency when compared to their counterparts.