Final answer:
A serum potassium level of 5.8 mEq/L indicates hyperkalemia, which is an elevated potassium blood level that can dangerously affect the heart and other bodily functions.
Step-by-step explanation:
A serum potassium level of 5.8 mEq/L is interpreted as a finding in a client with hyperkalemia. Hyperkalemia refers to an abnormally elevated level of potassium in the blood, which can occur from increased dietary intake of potassium as well as certain conditions such as renal failure, severe dehydration, and Addison's disease. This elevated potassium level can impair the function of skeletal muscles, the nervous system, and particularly the heart, potentially leading to serious cardiac complications.