0071643192.pdf

■ Always remember to check for and correct any associated hypomagne-
semia. In patients with hypokalemia and malnutrition, it is appropriate to
presumptivelygive magnesium along with potassiumreplacement.

Hyperkalemia (K+>4.5 mEq/L)

SYMPTOMS

Similar to hypokalemia

EXAM

■ Weakness and areflexia
■ Hypotension
■ Dysrhythmias: Peaked T waves →widened QRS →sine waves (M or W
complexes) (see Figure 7.3).

CAUSES

■ Common
■ Pseudohyperkalemia
■ Errors: Lab errors (hemolysis most common) and prolonged tourni-
quet application
■ Thrombocytosis or leukocytosis
■ Renal insufficiency or failure
■ DKA or other states of acidosis
■ Uncommon
■ Increased potassium intake
■ Increased cellular breakdown or turnover from trauma, burns, tumor
lysis, or rhabdomyolysis
■ GI bleed
■ Potassium salt substitutes
■ High-dose Pen-VK
■ Decreased renal excretion of K+
■ Type IV renal tubular acidosis most commonly from diabetes
■ Drugs such as K+sparing diuretics and ACE inhibitors, β-blockers,
digoxin, or succinylcholine
■ Adrenal and/or aldosterone insufficiency (Addison disease)

ENDOCRINE, METABOLIC, FLUID, AND

ELECTROLYTE DISORDERS

Hyperkalemia due to digoxin

toxicity needs digibind, not

calcium.

Do not forget to replace K+in

DKA patients, even if they

have normal serum K+

initially. Correction of acidosis

can lead to a precipitous and

dangerous drop in the K+.

R

P

S

Q

3.6 mEq/L

T

R

P

S

6.8 mEq/L

T

Q

R

S

8.4 mEq/L

T

Q

FIGURE 7.3. ECGs of hyperkalemia with peaked T waves progressing to sine waves.