The nurse is caring for a client with respiratory insufficiency. The arterial blood gas (ABG) results indicate a pH of 7.50 and a PaCO2 of 30 mm Hg, and the nurse concludes that the client is experiencing respiratory alkalosis. Which additional laboratory value would the nurse expect to note in this client?

Choice A reason: This is incorrect because low HCO3- and high PaCO2 are signs of metabolic acidosis, not alkalosis. Metabolic acidosis is a condition where the blood pH is lower than the normal range of 7.35 to 7.45, due to an excess of acids or a loss of bases in the body.

Choice B reason: This is incorrect because low PaCO2 and low HCO3- are signs of respiratory acidosis, not alkalosis. Respiratory acidosis is a condition where the blood pH is lower than the normal range of 7.35 to 7.45, due to impaired gas exchange or hypoventilation, which causes carbon dioxide to accumulate in the blood.

Choice C reason: This is correct because low PaCO2 and high HCO3- are signs of alkalosis. Alkalosis is a condition where the blood pH is higher than the normal range of 7.35 to 7.45, due to a loss of acids or an excess of bases in the body. There are two types of alkalosis: respiratory and metabolic. Respiratory alkalosis is caused by hyperventilation, which lowers the PaCO2 in the blood. Metabolic alkalosis is caused by vomiting, diuretics, or excessive intake of antacids, which raises the HCO3- in the blood.

Choice D reason: This is incorrect because high PaCO2 and high HCO3- are signs of compensation, not alkalosis. Compensation is a process where the body tries to restore the normal pH by adjusting the levels of PaCO2 and HCO3- in the opposite direction of the primary disorder. For example, if the patient has metabolic alkalosis, the respiratory system will try to compensate by retaining carbon dioxide and lowering the PaCO2. If the patient has respiratory alkalosis, the renal system will try to compensate by excreting bicarbonate and lowering the HCO3-.

Choice A reason: Sodium (Na+) imbalance can cause neurological symptoms such as confusion, seizures, or coma, but not abdominal pain or urinary retention.

Choice B reason: Calcium (Ca2+) imbalance can cause abdominal pain, urinary retention, and confusion, as well as muscle weakness, bone pain, and cardiac arrhythmias. These signs are the result of an inadequate supply of calcium, which is essential for nerve and muscle function, as well as bone health.

Choice C reason: Chloride (Cl-) imbalance can cause acid-base disorders such as metabolic acidosis or alkalosis, but not abdominal pain, urinary retention, or confusion.

Choice D reason: Phosphates (PO4^3^-) imbalance can cause bone and muscle problems, such as rickets, osteomalacia, or tetany, but not abdominal pain, urinary retention, or confusion.

Choice E reason: Potassium (K+) imbalance can cause cardiac and neuromuscular symptoms, such as arrhythmias, palpitations, muscle weakness, or paralysis, but not abdominal pain, urinary retention, or confusion.