Hypovolemic-hypotonic-hyponatremia

(ie, ↓↓ total body Na, ↓ TBW)

• Renal losses of Hypovolemic-hypotonic-hyponatremia

Extrarenal losses

• (UNa <10 mEq/L, UCl <10 mEq/L if alkalemia, FENa <1%):
  • hemorrhage,
  • GI loss (diarrhea or vomiting),
  • third-spacing (pancreatitis),
  • ↓ PO intake, insensible losses