Laboratory tests reveal the following electrolyte values for Mr. Smith: Na 135 mEq/L, Ca 8.5 mg/dL, Cl 102 mEq/L, and K 2.0 mEq/L. Which of the following values should the nurse report to the physician because of its potential risk to the client?

The correct answer is 'K.' Normal serum potassium levels range between 3.5 and 5.5 mEq/L. Mr. Smith's potassium level of 2.0 mEq/L is significantly below the normal range, indicating hypokalemia, which can lead to serious risks such as cardiac arrhythmias. The levels of sodium (Na), calcium (Ca), and chloride (Cl) are within normal ranges, so they do not pose an immediate risk to the client's health. Therefore, the nurse should report the low potassium level to the physician for prompt intervention.