Plasma tryptophan level in chronic renal failure

Area of Science:

• Biochemistry
• Nephrology
• Clinical Nutrition

Background:

• Chronic renal failure (CRF) is associated with complex metabolic disturbances.
• Tryptophan (Trp) is an essential amino acid crucial for protein synthesis and neurotransmitter production.
• Altered amino acid metabolism is a known complication in patients with impaired kidney function.

Purpose of the Study:

• To investigate total (Trp), free (fTrp), and bound (bTrp) tryptophan concentrations in patients with CRF.
• To compare Trp levels across different renal replacement therapy modalities: hemodialysis (HD), peritoneal dialysis (CAPD), and conservative (ND) treatment.
• To explore the relationship between Trp levels, kidney function, and plasma protein binding.

Main Methods:

• Plasma samples were collected from patients with CRF undergoing HD, CAPD, or conservative treatment.
• Concentrations of total, free, and bound tryptophan were quantified.
• Correlations with clinical parameters such as serum creatinine, albumin, transferrin, and body weight were analyzed.

Main Results:

• All patient groups (HD, CAPD, ND) exhibited significantly decreased total and bound tryptophan levels.
• Free tryptophan concentration remained unchanged in HD and CAPD groups but was reduced in the ND group.
• No correlation was observed between decreased bound tryptophan and plasma albumin or transferrin levels.
• Decreased body weight did not correlate with changes in total, free, or bound tryptophan.
• An inverse correlation was found between serum creatinine levels and the bound tryptophan/albumin ratio.

Conclusions:

• Patients with CRF experience tryptophan deficiency and impaired tryptophan binding to plasma albumin.
• These alterations in tryptophan metabolism affect tryptophan availability.
• The observed changes in tryptophan metabolism appear to correlate with the severity of kidney function impairment.