Final answer:
The nurse should prioritize and report the Potassium level of 5.4 mEq/L, as this is above the normal range and can lead to serious health risks, including cardiac complications.
Step-by-step explanation:
When reviewing a client's fluid and electrolyte status, the nurse should report to the provider any values that fall outside of the normal range. In this case, the finding that should be prioritized and reported is a Potassium level of 5.4 mEq/L. The normal blood potassium level is typically between 3.5 and 5.0 mEq/L. Elevated potassium levels, or hyperkalemia, can pose significant health risks, including cardiac problems. It is crucial to address this imbalance promptly to avoid complications.The other results listed are within the normal ranges: Blood Urea Nitrogen (BUN) of 15 mg/dL, Creatinine of 0.8 mg/dL, and Sodium of 143 mEq/L are all considered normal according to standard medical references, hence they do not require immediate attention.