A 23-year old-dancer presents with a chief complaint of weakness. She denies any other symptoms, including nausea or vomiting. She denies diarrhea. Her blood pressure is 80/40 mm Hg. There is no edema and the lungs are clear. Laboratory analysis of serum shows:
Sodium 126 mEq/L, Potassium 2.2 mEq/L, Bicarbonate 29 mEq/L, Magnesium 2.0 mg/dL,
Calcium 9.0 mg/Dl The most likely cause of the patient's weakness is an abnormality in which of the following?
|D|| Potassium |
a. The average dietary intake of potassium is approximately 50 to 100 mEq/d, which in the absence of hypokalemia is excreted primarily in the urine.
b. Extracellular potassium is maintained within a narrow range, principally by renal excretion of potassium, which can range from 10 to 700 mEq/d.
c. Although only 2% of the total body potassium (4.5 mEq/L x 14 L = 63 mEq) is located within the extracellular compartment, this small amount is critical to cardiac and neuromuscular function
d. ECG changes suggestive of hypokalemia include: U waves , T-wave flattening , ST-segment changes , Arrhythmias (especially if patient is taking digitalis
e. Treatment for hypokalemia consists of potassium repletion, the rate of which is determined by the symptoms.