The nurse is administering sodium polystyrene sulfonate to a client in acute kidney injury (AKI). Which laboratory finding indicates that the medication has been effective?
Glucose [Reference Range: 74 to 106 mg/dL (4.1 to 5.9 mmol/L)]
Hemoglobin (Hgb) [Reference Range:12-16 g/dL (120-160 g/L)]
Potassium (K+) [Reference Range: 3.5 to 5.0 mEq/L (3.5 to 5.0 mmol/L)]
Ammonia [Reference Range: Adult: 10 to 80 Mcg/dL (6 to 47 Mcmol/dL)]
A.
Serum ammonia level of 30 Mcg/dL (17.62 Mcmol /dL).
B.
Serum potassium level of 3.8 mEq/L (3.8 mmol/L).
C.
Serum glucose level of 120 mg/dL (6.7 mmol/L).
D.
Hemoglobin level of 13.5 g/dL (135 g/L).
The Correct answer and Explanation is:
The correct answer is B. Serum potassium level of 3.8 mEq/L (3.8 mmol/L).
Explanation:
Sodium polystyrene sulfonate (SPS), also known as Kayexalate, is a medication used to treat hyperkalemia (elevated potassium levels) by exchanging sodium ions for potassium ions in the gastrointestinal tract, thus lowering serum potassium levels. This is particularly important in the context of acute kidney injury (AKI), where the kidneys are unable to effectively excrete potassium, leading to dangerous hyperkalemia.
When evaluating the effectiveness of SPS treatment, the primary laboratory parameter of interest is the serum potassium level. The reference range for serum potassium is typically 3.5 to 5.0 mEq/L (3.5 to 5.0 mmol/L). A serum potassium level within this range indicates that the treatment has successfully lowered the elevated potassium levels.
In the given options:
- A. Serum ammonia level of 30 Mcg/dL (17.62 Mcmol/dL): While ammonia levels can be relevant in certain conditions (like hepatic encephalopathy), they are not directly affected by sodium polystyrene sulfonate. This option does not reflect the effectiveness of the treatment for hyperkalemia.
- B. Serum potassium level of 3.8 mEq/L (3.8 mmol/L): This level falls within the normal reference range for potassium. This indicates that the sodium polystyrene sulfonate has been effective in reducing the serum potassium level to a safe range.
- C. Serum glucose level of 120 mg/dL (6.7 mmol/L): Serum glucose levels are not influenced by sodium polystyrene sulfonate. This option is not relevant to the effectiveness of the treatment for hyperkalemia.
- D. Hemoglobin level of 13.5 g/dL (135 g/L): Hemoglobin levels are unrelated to potassium levels and the use of sodium polystyrene sulfonate. This option does not assess the effectiveness of the treatment for hyperkalemia.
In summary, the serum potassium level is the key indicator of the effectiveness of sodium polystyrene sulfonate. A level of 3.8 mEq/L demonstrates that the medication has successfully managed the hyperkalemia associated with acute kidney injury.