Beyond The Current Paradigm: Recent Advances in The Understanding of Sodium Handling – Guest Editors: Stanley Shaldon and Joerg Vienken: Reducing Sodium Intake in Hemodialysis Patients

Abstract

A low salt diet is beneficial for the whole population but has particular advantages for hemodialyis patients because of the role of salt restriction in the management of hypertension and interdialytic weight gain (IDWG). Education on dietary salt intake based on general healthy eating guidelines, such as the "DASH-sodium" diet, should be provided for staff, families, and carers as well as patients. Anuric hemodialysis patients will need to take in approximately 1 l of water for every 8 g salt consumed. Patients who restrict salt intake to <6 g/day, and drink only when thirsty, should gain no more than 0.8 kg/day. Those with significantly greater weight gains, but predialysis serum sodium close to or higher than the dialysate sodium, need further review of their salt intake. Attempts to restrict fluid intake in these patients will be futile. Patients with high interdialytic weight gain (IDWG) and low predialysis sodium should be assessed for other reasons for fluid intake, such as high blood glucose or social drinking. For patients with poor tolerance of fluid removal during dialysis, and those who are hypertensive in the absence of fluid overload, a salt intake 5 g/day or less may be required. Dietary advice for these patients should be customized to ensure that they do not become malnourished.

Dialysate Sodium Concentration and the Association with Interdialytic Weight Gain, Hospitalization, and Mortality

“…Using a patient's predialysis SNa as a reference to prescribe individualized or tailored DNa has thus been considered rational (3,10,11), and various prospective interventional trials have found a significant decrease in IDWG by reducing DNa (10,12). As a result of previous guidelines and recommendations (8,9,13) and recent observational studies and commentaries (7,14,15), DNa tailoring may become routine clinical practice.…”

“…Additional sodium can also be removed by diffusive transport if the dialysate sodium (DNa) level is set below the predialysis serum sodium (SNa) concentration (2,3). Vice versa, higher DNa levels translate into higher dialysate-toSNa gradients, which are associated with thirst (3,4), interdialytic weight gain (IDWG) (5-7), and hypertension (8,9).…”

Improving Volume Status by Comprehensive Dietary and Dialytic Sodium Management in Chronic Hemodialysis Patients

“…Is it feasible to lower the dietary salt intake of the average dialysis patient to the level as recommended by guidelines [17,55] ? Buying low-sodium products can be challenging, since sodium is added to nearly all manufactured foods [56] .…”

Sodium Setpoint and Sodium Gradient: Influence on Plasma Sodium Change and Weight Gain

“…Advanced renal failure typically results in sodium retention [1,2,3,4] and hypertension [5,6,7,8,9,10]. Modern renal replacement therapy removes sodium by means of convection/ultrafiltration, as well as by diffusion/dialysis.…”

“…Modern renal replacement therapy removes sodium by means of convection/ultrafiltration, as well as by diffusion/dialysis. Despite complex processes at the dialysis membrane, the patient plasma sodium (PNa) concentration at the end of dialysis approximates the dialysate sodium (DNa) level [10]. The difference between DNa and PNa may be labeled the ‘sodium gradient’.…”