0071643192.pdf

CAUSES

■ History and physical are usually sufficient in diagnosing the cause of potas-

sium loss.

■ Renal losses

■ With metabolic acidosis include renal tubular acidosis and postob-

structive diuresis.

■ With metabolic alkalosis include diuretics, Cushing syndrome, and

licorice ingestion (causes increased cortisol).

■ Nonrenal losses, which include

■ Vomiting, diarrhea, or suctioning

■ Colon cancer

■ Villous adenoma

■ Excessive sweating

■ Decreased intake

■ Intracellular shift

■ Familial periodic paralysis

■ Insulin or albuterol administration

■ Endocrine: Hyperthyroidism

TREATMENT

■ Acute hypokalemia

■ Uncommon but considered life-threatening

■ 40 mEq of K+raises the serum level approximately 1 mEq/L acutely,

but total body K+deficit may be much larger.

■ Goal is to correct K+to at least 3.5 mEq/L.

■ Cardiac monitoring

■ Chronic hypokalemia

■ Not usually life-threatening

■ K+replacement should be done orally if there is no contraindication.

COMPLICATIONS

■ Both inadequate and overzealous K+replacement can lead to cardiac dys-

rhythmias and death.

■ Oral replacement safer than IV but 10 mEq/hour IV is safe.

ENDOCRINE, METABOLIC, FLUID, AND

ELECTROLYTE DISORDERS

R

P

S

U

3.9 mEq/L

T

P

S

T

2.7 mEq/L

U

P

S

1.3 mEq/L

U

R R

T

FIGURE 7.2. ECGs of hypokalemia with characteristic U waves and ST depression.