Post-Dialysis Fatigue Is Not Associated with Serum Lactate Levels in Patients on Chronic Hemodialysis

<b>Background/Objectives:</b> To measure the peri-dialytic serum lactate, sodium, potassium, calcium, and pH and base excess in chronic hemodialysis patients with and without post-dialysis fatigue (PDF). <b>Methods</b>: Patients were asked "Do you feel fatigued after dialysis?" Each patient was invited to rate the intensity, duration, and frequency of PDF from one to five. The recovery time after the hemodialysis session (TIRD) was calculated, and inviting patients were to answer the following single open-ended question: "How long does it take you to recover from a dialysis session?" Pre- and post-dialysis arterial blood was sampled, and pH, bicarbonates, base excess, sodium, calcium, potassium, and lactate were measured. <b>Results:</b> One hundred fifty-eight patients were included in the study. One hundred seventeen patients declared to suffer from PDF and forty-one did not. Median [range] PDF frequency, intensity, duration, and TIRD were 5 (1-5), 4 (1-5), 3 (1-5), and 12 h (1-48), respectively. Seventy patients had a TIRD ≤ 12 h and forty-seven had a TIRD > 12 h. Median post-dialysis and post-dialysis/pre-dialysis difference serum lactate levels (mmol/L) did not differ between patients with and without PDF (<i>p</i> = 0.111 and <i>p</i> = 0.395, respectively). In addition, the distribution of patients according to post-dialysis serum lactate levels was similar in the presence or absence of PDF. The median post-dialysis and post-dialysis/pre-dialysis difference serum lactate concentrations did not differ significantly according to the score of the PDF intensity and PDF duration (<i>p</i> = 0.928 and 0.935, <i>p</i> = 0.610 and 0.548, respectively). Finally, we stratified patients into two groups according to the length of TIRD: ≤12 h and >12 h. The median post-dialysis serum lactate concentrations did not differ significantly between the two groups (<i>p</i> = 0.862) as well as the median post-dialysis/pre-dialysis difference (<i>p</i> = 0.583). Also, the distribution of patients according to post-dialysis serum lactate levels was similar in the two groups. <b>Conclusions:</b> PDF and TIRD are not associated with peri-dialytic changes in serum lactate in patients on chronic hemodialysis.