Which of the following describes serum Ca2+? a. Approximately ...

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Which of the following describes serum Ca2+?
 
  a. Approximately 30 of the serum Ca2+ is ionized and combined with plasma anions.
  b. Acidemia decreases the serum levels of ionized Ca2+.
  c. More than half of the serum Ca2+ is nonionized and bound to plasma albumin.
  d. Serum Ca2+ is present in three forms: ion-ized, protein bound, and complex.

Question 2

What is the most common cause of hyperkalemia?
 
  a. Cardiac arrest
  b. Metabolic alkalosis
  c. Renal failure
  d. Respiratory acidosis

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Answer to Question 1

ANS: D
Calcium is present in the blood in the following three forms: ionized, protein bound, and com-plex. Approximately 50 of serum calcium is ionized (Ca2+) and is physiologically active. An additional 10 forms calcium anion complexes. The remaining 40 is bound to plasma proteins, primarily albumen. Ionized calcium is physiologically active in processes such as enzyme activity, blood clotting, neuromuscular irritability, and bone calcification. Acidemia increases, and alkale-mia decreases, the concentration of Ca2+ in the serum.

Answer to Question 2

ANS: C
Hyperkalemia (elevated serum potassium) is most common in renal insufficiency.

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