Chronic hyponatremic encephalopathy in postmenopausal women - Association of therapies with morbidity and mortality

Context Chronic hyponatremia in postmenopausal women is a common clinical p roblem often viewed as benign. Fluid restriction is usually the recommended therapy, largely because the extent of morbidity is unknown and because it has been postulated that intravenous (IV) sodium chloride may cause brain damage. Objective To compare IV sodium chloride with fluid restriction in the treat ment of postmenopausal women with chronic symptomatic hyponatremia. Design Nonrandomized prospective study. Setting Two university medical centers and affiliated community hospitals. Patients A total of 53 postmenopausal women with chronic symptomatic hypona tremia (chronic plasma sodium <130 mmol/L in the presence of central nervou s system manifestations) treated consecutively from 1988-1997 and followed up for 1 year. The mean (SD) age of the patients was 62 (11) years. Interventions The therapeutic interventions were IV sodium chloride before respiratory insufficiency (n = 17), IV sodium chloride after respiratory in sufficiency (n = 22), and fluid restriction only (n = 14). Main Outcome Measures Morbidity and neurological outcome at 4 months or lon ger as assessed by cerebral performance category (CPC) in relation to the t herapy, initial plasma sodium level, and rate of correction. Results Chronic symptomatic hyponatremia(mean [SD] sodium level 111 [12] mm ol/L) was present for 5.2 [4.5] days. Death or major morbidity occurred in 44 (83%) of 53 patients, including 10 with orthopedic injury. Twelve patien ts had hypoxemia (PO2 = 63 [25] mm Hg) and cerebral edema. Among patients w ho received IV sodium chloride before respiratory insufficiency, plasma sod ium levels were increased by 22 (10) mmol/L in 35 hours and patients had a CPC of 1.0 (normal or slight disability). Among patients who received IV so dium chloride after respiratory insufficiency, plasma sodium levels were in creased by 30 (6) mmol/L in 41 hours and patients had a CPC of 3.0 (1.2) (s evere disability). Among patients who had fluid restriction only, plasma so dium levels were increased by 3 (2) mmol/L in 41 hours and patients had a C PC of 4.6 (0.7) (4 = persistent vegetative st-ate; 5 = death). The outcomes did not correlate with either the initial plasma sodium level (r = 0.05, P >.12) or the rate of correction (r = 0.31, P>.10). Conclusions Chronic symptomatic hyponatremia in postmenopausal women can be associated with major morbidity and mortality. Therapy with IV sodium chlo ride was associated with significantly better outcomes than fluid restricti on.