Too little water or too much: hyponatremia due to excess fluid intake

Hyponatremia associated with diarrhea is usually caused by dehydration, with salt loss accompanying the excessive loss of water. On the other hand, hyponatremia in this setting can occasionally be caused by excess ingestion or administration of hypotonic fluids (1, 2). In this report, we describe the differential diagnosis of hyponatremia in an infant.