Guillain-Barré syndrome and hyponatraemia

Hyponatraemia is a recognized association of the Guillain-Barré 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.

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.

Clinical record audit of 84 patients with GBS admitted to Christchurch Hospital, New Zealand, over a 10-year period.

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 > or =50 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).

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).