Review article

TBW

Hyponatremia is a disorder of water regulation. Most cases of hyponatremia are from problems in water excretions, kidney failure or CHF.

  1. Pseudohyponatremia: serum Na is normal but serum osmolality is normal
  2. Hyponatremia with hypertonicity
  3. Hyponatremia with hypotonicity (“true” hyponatremia): Requires continued water intake

Workup

#1 FLUID RESTRICTION!!! to < 800 ml/24 hrs.  This will buy you some time (hours).

  1. When faced with a low sodium value, first check a serum osmolality.
  2. If you're not sure if the pt is dehydrated (vomiting) or SIADH, give slow NS.

CHF, nephrotic syndrome, CRH, cirrhosis, thiazide diuretics Fig 3-2 Tx Loop diuretic causes more loss of water than Na, so give.