Tryptophan and Kynurenine Levels and Its Association With Sleep, Nonphysical Fatigue, and Depression in Chronic Hemodialysis Patients

Our study indicates disturbed TRP metabolism in HD patients, but low TRP levels were not related with sleep disturbances, depression, and fatigue. In contrast, KYN levels, a metabolite of TRP, were much higher in HD patients compared with controls, and higher KYN associated with depression and fatigue. Further studies exploring the biological and functional consequences of increased TRP catabolism in HD patients are warranted.