Figure 3

Cell volume in acute or subacute hypernatremia and following rapid correction of hypernatremia. When hypernatemia develops acutely, all cells are reduced in size (the degree of cell volume reduction reflects the degree of hypernatremia). When hypernatremia is present for 36-48 hours or more (= subacute hypernatremia), cell volume reduction persists in most cells, including muscle cells (upper panel). However, brain cells (and red blood cells) tend to restore their normal cell volume (lower panel). An abrupt normalization of sodium level in children with subacute or chronic hypernatremia pathologically increases the volume of brain cells (and red blood cells). Swelling of cells, which does not have serious consequences when it occurs in most organs, may have devastating consequences when it occurs in the brain (lower panel, right).