Inappropriate secretion of antidiuretic hormone in Guillain-Barré syndrome.

Hyponatraemia occurred in five cases with severe Guillain-Barré syndrome who required assisted respiration. In one, the syndrome of inappropriate secretion of ADH was demonstrated and probably accounted for the hyponatraemia in the other four. The water overload thus produced may have contributed to the neurological deterioration and the peripheral and pulmonary oedema seen in some of these cases.