Which electrolyte imbalance does kayexalate (sodium polysteyrene) treat?

A. Positive Trousseau's sign: Hypocalcemia increases neuromuscular excitability, which can lead to carpopedal spasm when a blood pressure cuff is inflated—a phenomenon known as Trousseau’s sign. This is a classic clinical indicator of low calcium levels and reflects the heightened responsiveness of nerves and muscles to stimulation.

B. Muscle weakness: Although hypocalcemia often causes muscle cramps and spasms, some clients may also experience generalized muscle weakness due to impaired excitation-contraction coupling in skeletal muscles. The decreased availability of calcium for muscle contraction reduces muscle strength while still maintaining increased neuromuscular irritability.

C. Decreased muscle tone: Hypocalcemia typically results in increased, not decreased, muscle tone due to neuromuscular excitability. Reduced muscle tone is more commonly associated with hypercalcemia or neuromuscular disorders that impair contraction rather than low calcium levels.

D. Polyuria: Polyuria is not a direct symptom of hypocalcemia. It is more often associated with hypercalcemia, which can impair renal concentrating ability, or with conditions affecting antidiuretic hormone or renal function. Hypocalcemia primarily affects neuromuscular and cardiac function rather than urine output.

E. Hyporeflexia: Hypocalcemia generally causes hyperreflexia due to increased neuromuscular excitability. Decreased reflexes are more characteristic of hypercalcemia or neuromuscular blockade. Therefore, hyporeflexia would not be expected in a client with low calcium levels.

A. Computed tomography (CT) scan of the chest: A chest CT provides detailed images and can detect subtle infiltrates or complications, but it is not the first-line diagnostic tool for suspected pneumonia due to higher cost, increased radiation exposure, and the need for contrast in some cases. CT is typically reserved for complicated or atypical presentations.

B. Chest X-ray: Chest X-ray is the standard initial diagnostic test for suspected pneumonia. It can identify areas of consolidation, infiltrates, or pleural effusions, confirming the presence and extent of infection. It is widely available, quick, and provides sufficient information for initial diagnosis and treatment planning.

C. Ultrasound: Chest ultrasound is not routinely used to diagnose pneumonia. It can be useful in detecting pleural effusions or guiding thoracentesis but lacks the ability to reliably visualize lung parenchyma and infiltrates compared with a chest X-ray.

D. Magnetic resonance imaging (MRI) of the chest: MRI provides excellent soft tissue detail but is rarely used for pneumonia diagnosis because it is costly, time-consuming, and less practical in an emergency setting. It is reserved for complex thoracic pathology or mediastinal evaluation.