Guillain-Barre syndrome and hyponatraemia

Background: Hyponatraemia is a recognized association of the Guillain-Barre syndrome (GBS) and is also known to occur after the administration of intravenous infusion of gamma globulin (IVIG), a treatment often used in management of GBS. Aims: To document serum sodium concentration in GBS patients before, during and after management procedures (including IVIG) positive pressure ventilation (PPV) and the use of medications capable of causing a low serum sodium. To consider whether pseudohyponatraemia might be a contributory factor. To assess whether hyponatraemia is a predictor of poor outcome. Methods: Clinical record audit of 84 patients with GBS admitted to Christchurch Hospital, New Zealand, over a 10-year period. Results: Serum sodium concentration was significantly low (<133 mmol/L) in 26 of 84 (31%) patients. In 12 of these cases the hyponatraemia developed during or after IVIG, suggesting that pseudo-hyponatraemia was a contributing factor. Six (7%) significantly hyponatraemic patients died, but no eunatraemic or slightly hyponatraemic patient died (P = 0.001). Six of 38 patients aged greater than or equal to50 years died, whereas none of the 46 patients aged <50 years died (P = 0.007). Five of 19 ventilated patients died but only one of 65 non-ventilated died (P = 0.002). Conclusions: Significant hyponatraemia occurred in 26 (31%) of the patients, but in 12 of these it appeared likely that pseudohyponatraemia caused by IVIG was a contributing factor. Hyponatraemic patients have a poorer prognosis than eunatraemic patients, however it is difficult to separate this factor from other poor prognostic factors (older age and PPV).