Protocolo diagnóstico y tratamiento del síndrome de secreción inadecuada de ADH

Abstract

EpidemiologyHyponatremia (Na < 135 mmol/l) is the most common electrolyte disturbance in hospitalised patients. SIADH is the most common cause of normovolemic hyponatremia. PathogenesisIn the SIADH the inhibition of ADH secretion does not occur when the plasma osmolality falls below 280 mOsm/kg, so free water is reabsorbed in the renal collecting tubule, causing greater hemodilution and hyponatraemia with inappropriately elevated urine osmolality. Can be classified into four main etiologic groups: tumors, central nervous system conditions, drugs and pulmonary disorders. Clinical manifestationsSIADH clinical manifestations derive from hyponatremia and are predominantly neurological. DiagnosisIs based on several criteria: reduced plasma osmolality (< 275 mOsm/kg), urine osmolality above 100 mOsm/kg, clinical euvolemia, urinary sodium excretion above 40 mmol/l, normal renal function and excluding hypothyroidism and adrenal insufficiency. TreatmentIs based mainly on the management of the underlying disease and it depends on the magnitude of the hyponatremia and its velocity and the presence and severity of neurological symptoms. PrognosisSIADH causes increased morbidity and mortality. Even mild, apparently asymptomatic hyponatremias may worsen the outcome of the patient.