What is hyponatremia?
Serum sodium level under 135 mEq/L
What are sodium imbalances usually associated with?
Fluid volume imbalances.
What are three basic causes of hyponatremia?
Increased sodium excretion
Inadequate sodium intake
Dilution of serum sodium
What causes increased sodium excretion? (7)
Excessive diaphoresis Diuretics Vomiting Diarrhea Wound drainage, especially GI Kidney disease Decreased secretion of aldosterone
What causes inadequate sodium intake? (2)
Fasting, NPO status
What causes dilution of serum sodium? (6)
Excessive ingestion of hypotonic fluids or irrigation with hypotonic fluids
Syndrome of inappropriate antidiuretic hormone secretion
What are the cardiovascular signs and symptoms of hyponatremia in a normovolemic patient?
Rapid pulse rate, normal blood pressure
What are the cardiovascular signs and symptoms of hyponatremia in a hypovolemic patient? (4)
Thready, weak, rapid pulse rate
Flat neck veins
Normal or low central venous pressure
What are the cardiac signs and symptoms of hyponatremia in a hypervolemic patient? (3)
Rapid, bounding pulse
Blood pressure normal or elevated
Normal or elevated central venous pressure
What are the respiratory signs and symptoms of hyponatremia?
Shallow, ineffective respiratory movement is a late manifestation related to skeletal muscle weakness
What are the neuromuscular signs and symptoms of hyponatremia? (2)
Generalized skeletal muscle weakness that is worse in the extremities
Diminished deep tendon reflexes.
What are the central nervous system signs and symptoms of hyponatremia? (5)
Headache Personality changes Confusion Seizures Coma
What are the gastrointestinal signs and symptoms of hyponatremia? (3)
Increased motility and hyperactive bowel sounds
Abdominal cramping and diarrhea
What are the renal signs and symptoms of hyponatremia?
Increased urinary output
What are the integumentary signs and symptoms of hyponatremia?
Dry mucous membranes.
What are the laboratory findings that indicate hyponatremia? (2)
Serum sodium level less than 135 mEq/L
Decreased urine specific gravity
What intervention should be implemented if the hyponatremia is accompanied by fluid volume deficit?
IV sodium chloride infusions are administered to restore sodium content and fluid volume
What intervention should be implemented if the hyponatremia is accompanied by a fluid volume excess?
Osmotic diuretics are administered to promote the excretion of water rather than sodium
What intervention should be implemented if hyponatremia is caused by inappropriate or excessive secretion of antidiuretic hormone?
Medications that antagonize antidiuretic hormone may be administered.
What is the interaction between hyponatremia and lithium?
Hyponatremia can cause diminished lithium excretion, resulting in toxicity