Internal Medicine

0521779407-09 CUNY1086/Karliner 0 521 77940 7 June 13, 2007 7:54

Hyponatremia 793

➣Hypertonic saline (3% NaCl)

➣Furosemide may be used to increase free water excretion.

➣Frequent monitoring of serum electrolytes is essential.

■Chronic Symptomatic Hyponatremia

➣Slow correction

➣Hypertonic saline (for seizures only) or normal saline with

furosemide is used.

➣Replace sodium, potassium and water losses if excessive.

■Chronic Asymptomatic Hyponatremia – Euvolemic or unknown

cause

➣a) Treat underlying cause: hypothyroidism, adrenal insufficiency,

drugs causing SIADH

➣If etiology is unclear, the following general measures are

recommended:

Fluid restriction to 0.5–1 L/day (all fluids)

Increase solute excretion: This will improve free water excre-

tion – Urea (30–60 g/day), NaCl (2–3 g/day) with furosemide

are options to increase solute excretion.

Drugs: Demeclocycline agent of choice. Lithium not used.

Newer agents: V2 receptor antagonists increase selective water

excretion in cirrhosis, heart failure and SIADH

■Hypovolemic Hyponatremia

➣Restore ECF volume (crystalloids and colloids).

➣Replace potassium.

➣Stop diuretics.

■Hypervolemic hyponatremia:

➣Marker of poor prognosis

➣Needs attention to underlying disorder

➣Difficult to treat

➣V2 antagonist may be helpful.

➣Fluid and Na restriction is the mainstay of therapy.

➣Loop diuretics (or change from HCTZ to loop diuretic) usually

needed

➣ACE inhibitors required in cardiac failure and nephrotic syn-

drome

follow-up

n/a

complications and prognosis

■Due to hyponatremia