Abstract:
Introduction: For Chronic Kidney Disease (CKD) stage stages 3b to 5, a low-protein diet (LPD: 0.6 g/kg/day) or a very low-protein diet (VLPD: 0.3–0.4 g/kg/day) is necessary, depending on the severity of the disease. Indeed, a low-protein diet can slow down glomerular hypertension and halt the progression of CKD to end-stage renal disease requiring dialysis. A reduction in protein intake inevitably results in a significant reduction in amino acid requirements (-17–28% of the daily requirement), which increases the risk of sarcopenia and/or protein energy wasting.
Methods: These diets must be supplemented with Essential Amino Acids (EAA) and their ketoanalogues (KEAAs/EAAs). Recently, new mixtures of free amino acids that can be rapidly incorporated directly into cells have been produced. When the patient enters maintenance dialysis, however, the scenario changes completely. Dialysis treatment is essential for survival due to the significant purification of numerous toxic nitrogenous molecules of different molecular weights which originate primarily from protein intake. However, patients on haemodialysis or peritoneal dialysis must consume 1.2 g of protein per kg of body weight per day, alongside a caloric intake of 30–35 kcal per kg of body weight per day to maintain metabolic equilibrium.
Results: Unfortunately, contact between blood and dialysis membranes produces hypercatabolism, primarily due to the release of numerous cytokines. The most significant metabolic effect is not so much the modest loss of albumin, but the huge loss of amino acids, which, due to their low molecular weight, are easily lost in enormous quantities (5 to 7 g per session) in the dialysis waste fluid-equivalent to a weight of 1.5-1.8 kg per year or more-leading to progressive muscle loss and accelerated sarcopenia and PEW.
Discussion: In order to interrupt or slow this phenomenon, it is essential to replace what is lost using mixtures if possible tailored to the plasma asset and to quantity and type of amino acids lost during the dialysis session. Added to this, it is a serious intestinal inflammatory/absorptive alteration already caused by the uremic state, which affects the intestinal microbiota.
Conclusion: It is important to emphasise that in CKD, but particularly in dialysis patients, these must be replaced, otherwise malnutrition, sarcopenia and PEW may result.
