Asymptomatic hyponatremia in peritoneal dialysis patients: an algorithmic approach

MUSSO CG; JOANNE M. BARGMAN

INTERNATIONAL UROLOGY AND NEFROLOGY

Springer

Año: 2014

0301-1623

Editor,Hyponatremia is a serious electrolyte problem, with significant prevalence (around 15 %) and unique pathophysiological characteristics in peritoneal dialysis patients [1, 2, 3, 4]. We have designed an algorithm for guiding assessment and therapeutic approach to the asymptomatic form of this disorder. Low serum sodium concentration in peritoneal dialysis can be induced by one or more of the following mechanisms:water and salt excess due to high oral intake (water in excess of sodium) and/or low water excretion (insufficient ultrafiltration). This situation occurs with an increase in body weight, as well as clinical signs of volume overload (edema, venous congestion, and hypertension) (5)extracellular fluid sodium deficit due to a low intake (low sodium diet) and/or excess sodium loss (excessive ultrafiltration). Clinical clues include a reduction in body weight, signs of volume contraction (hypotension, orthostatic hypotension, and axillary dryness), and low total body water documented by bioelectrical impedance analysis (BIA) [5, 6, 7].potassium deficit due to low oral intake (low potassium diet) and/or excess potassium loss (such as with diarrhea). Intracellular potassium depletion induces sodium to shift from the extracellular compartment to the intracellular one, in order to keep body compartments electrically neutral. The flux of sodium from the extracellular fluid to the intracellular compartment, leads to extracellular volume contraction. This scenario presents with a reduction in body weight and there may be clinical signs of hypovolemia, but not always hypokalemia [1, 8].intracellular phosphate/potassium deficit due to malnutrition. This phenomenon leads to intracellular hypo-osmolarity and consequently to water redistribution to extracellular compartment. This mechanism of dilutional hyponatremia presents with reduced body weight (lean mass reduction) but without signs of volume contraction [6, 8].free water excess due to an inadequate vasopressin suppression secondary to drugs (opioids, psychotropic medications), endocrinopathies (hypothyroidism, hypoaldosteronism), and other diseases: neurologic, pulmonary, or paraneoplastic ones) in a setting of significant residual renal function (RRF): GFR: 15?20 ml/min/1.73 m2, such as those patients who start peritoneal dialysis ?earlier? due to refractory hyperkalemia or concomitant cardiac failure [9].change in the set point for serum sodium tonicity: osmostat reset. This is a hypothesis and should be a diagnosis of exclusion (1)The last two clinical settings mentioned above (free water excess and reset osmostat) typically present without edema or body weight change.Then, based on the above data, we delineated the following algorithm for evaluating asymptomatic hyponatremia in peritoneal dialysis patients