Page 1670 - Saunders Comprehensive Review For NCLEX-RN

E. Homocysteine: Elevated levels may increase the risk of
cardiovascular disease; normal value is 4.5 to 11.9 mcmol/L (4.5 to
11.9 mcmol/L), age and gender dependent.
F. Highly sensitive C-reactive protein (hsCRP): Detects an
inflammatory process such as that associated with the
development of atherothrombosis; a level less than 1 mg/L is
considered low risk, and a level greater than 3 mg/L places the
client at high risk for heart disease.
G. Microalbuminuria: A small amount of protein in the urine has
been a marker for endothelial dysfunction in cardiovascular
disease.
H. Electrolytes (refer to Chapters 8 and 10)

1. Potassium

a. Hypokalemia causes increased cardiac
electrical instability, ventricular
dysrhythmias, and increased risk of
digoxin toxicity.
b. In hypokalemia, the electrocardiogram
(ECG) shows flattening and inversion
of the T wave, the appearance of a U
wave, and ST depression.
c. Hyperkalemia causes asystole and
ventricular dysrhythmias.
d. In hyperkalemia, the ECG may show
tall, peaked T waves, widened QRS
complexes, prolonged PR intervals, or
flat P waves.
2. Sodium
a. The serum sodium level decreases with
the use of diuretics.
b. The serum sodium level decreases in
heart failure, indicating water excess.
I. Calcium
1. Hypocalcemia can cause ventricular dysrhythmias,
prolonged ST and QT intervals, and cardiac arrest.
2. Hypercalcemia can cause a shortened ST segment and
widened T wave, atrioventricular block, tachycardia
or bradycardia, digitalis hypersensitivity, and cardiac
arrest.
J. Phosphorus level: Phosphorus levels should be interpreted with
calcium levels, because the kidneys retain or excrete one
electrolyte in an inverse relationship to the other.
K. Magnesium
1. A low magnesium level can cause ventricular
tachycardia and fibrillation.
2. Electrocardiographic changes that may be observed
with hypomagnesemia include tall T waves and

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