-Serum sodium < 135 mEq/L (may not see manifestations until 125 mEq/L
-Causes: diuretics, kidney disorders, adrenal insufficiency, vomiting, diarrhea, gastrointestinal suction, GI tube irrigation with water instead saline, repeated water enemas, excessive sweating, loss of skin surface (burns) and 3rd spacing.
--decrease in serum osmolality, ceslls swell
-Manifestations: early( muscle cramps, weakness, fatigue),
below 120 mEq/L: headache, depression, dulled sensorium, personality changes, irritability, lethargy, hyperreflexia, muscle twitching and tremos.
If very low coma likley
- decreased sodium osmolality, decreased hematocrit and BUN, weight loss, lethargy, stupor, coma, anorexia, nausea, vomiting, diarrhea, hypotension, shock