Chronic hyponatremia more than 48 hours or duration unclear vs acute hyponatremia within 48 hours

• IV fluid normal saline 100 cc per hours if dehydration vs fluid restrict obstruction if SIADH vs diuretic for volume overload  CHF
• Serum osmolality, urine sodium and urine osmolality, TSH, cortisol
• Repeat BNP every 4 hours,
• Goal to increase serum sodium no more than 6-8 mEq /day to prevent risk of osmotic demyelination syndrome (chronic hyponatremia)
• Severe hyponatremia less than 120 or moderate hyponatremia 120-129 with a severe symptom with a seizure, obtundation or respiratory arrest, start on hypertonic 3% saline immediately at 15-30 cc/hours, consult Nephrology
• Monitor sodium hourly while on the hypertonic saline.  If too fast correcting, started on D5W infusion
• SIADH:  (Low uric acid) Fluid restriction 800 cc/hours, salt tablet and diuretic
• Hypervolemic status:  Fluid restriction and diuretic

Etiology: Serum sodium, Serum osmolality, urine osmolality and urine sodium, TSH, cortisol

• Serum osmol:  Greater than 295 hyper osmol (fastitious, hyperglycemia), normal to 285-295 (pseudo lipid protein), low less than 285 (hypo Osmo/hypotonic-true hyponatremia)
• Urine osmol:  Greater than 200 (ADH dependent), less than 100 to 200 (ADH independent:  Renal failure, Tea and toast, beer potomania, polydipsia)
• Urine sodium:  Less than 20 -volume status-(hypovolemic:  Dehydration, GI loss, nausea and vomiting, renal loss), (hypervolemic:  CHF, liver failure, renal failure), greater than 40 -euvolemic (SIADH, thyroid, glucose deficiency)