In addition, no significant correlation between Ki-67 index and all 5 metabolic parameters were revealed neither in the paraganglioma group (R2 range: 0.097–0,250, P > 0.05) nor in the UCD group (R2 range: – 0.636 to – 0.031, P > 0.05). Here, MKI67 is linked to urea cycle disorder.