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Fatigue and plasma tryptophan levels in patients on chronic hemodialysis

2015; Elsevier BV; Volume: 88; Issue: 3 Linguagem: Inglês

10.1038/ki.2015.186

1523-1755

Maurizio Bossola, Luigi Tazza,

Bipolar Disorder and Treatment

To the Editor: Mutsaers et al.1Mutsaers H.A. Masereeuw R. Olinga P. Altered tryptophan metabolism and CKD-associated fatigue.Kidney Int. 2014; 86: 1061-1062Abstract Full Text Full Text PDF PubMed Scopus (11) Google Scholar have recently suggested that there is a direct link between tryptophan metabolism and the circadian rhythm in patients with chronic kidney disease (CKD) and that altered tryptophan metabolism as etiology for CKD-associated fatigue warrants further investigation. We have recently measured, by liquid chromatography with fluorometric detection previously described,2Bossola M. Scribano D. Colacicco L. et al.Anorexia and plasma levels of free tryptophan, branched chain amino acids, and ghrelin in hemodialysis patients.J Ren Nutr. 2009; 19: 248-255Abstract Full Text Full Text PDF PubMed Scopus (21) Google Scholar plasma free tryptophan (FTRP) levels, large neutral amino-acid (LNAA) levels, and the FTRP/LNAA ratio in 50 patients on chronic hemodialysis and correlated with fatigue assessed through the SF-36 Vitality subscale.3Mingardi G. Cornalba L. Cortinovis E. et al.Health-related quality of life in dialysis patients: a report from an Italian study using the SF-36 Health Survey: DIA-QOL Group.Nephrol Dial Transplant. 1999; 14: 1503-1510Crossref PubMed Scopus (172) Google Scholar Patients were divided into two groups, fatigued (SF-36 Vitality subscale score ≤50) and not-fatigued (SF-36 Vitality subscale score ≤50).4Collado-Hidalgo A. Bower J.E. Ganz P.A. et al.Inflammatory biomarkers for persistent fatigue in breast cancer survivors.Clin Cancer Res. 2008; 12: 2759-2766Crossref Scopus (307) Google Scholar The two groups were similar for age, sex, primary cause of end-stage renal disease, body mass index, dialytic age, serum albumin, creatinine, and urea. As shown in the Table 1, the two groups did not differ significantly for the plasma levels of FTRP, LNAA, and FTRP/LNAA ratio. In addition, the correlation between fatigue and FTRP (correlation coefficient: -0.001; P=0.999), LNAA (-0.072; P=0.606), and FTRP/LNAA ratio (0.035; P=0804) was not statistically significant.Table 1Fatigue and plasma levels of FTRP and other LNAA in fatigue and not-fatigued patients (large neutral amino-acids)Fatigued (n=25)Not-fatigued (n=25)PFTRP (nmol/ml)15.2±7.714.6±12.60.839LNAA (nmol/ml)529±163533±1070.918FTRP/LNAA0.029±0.0140.026±0.0210.551Abbreviations: FTRP, plasma free tryptophan; LNAA, large neutral amino-acids.It seems that there is no correlation between fatigue and plasma tryptophan levels in patients on chronic hemodialysis. Open table in a new tab Abbreviations: FTRP, plasma free tryptophan; LNAA, large neutral amino-acids. It seems that there is no correlation between fatigue and plasma tryptophan levels in patients on chronic hemodialysis.