Changes in plasma concentrations of kynurenine pathway intermediates (A–D) across the investigated study groups: healthy children, children with ADPKD (normal eGFR), healthy adults and adults with ADPKD (eGFR above or below 60 mL/min/1.73m2, respectively). All concentrations are presented as ng/mL, except for tryptophan (calculated in μg/mL) and MCP-1 (calculated in pg/mL). Significance levels (after Bonferroni adjustment): healthy subjects versus ADPKD patients (children and adults, respectively): *p < 0.0056, ***p < 0.0001 and children versus adults with ADPKD: #p < 0.0056, ###p < 0.0001