Final answer:
The nurse should report a potassium level of 5.5 mEq/L to the provider.
Step-by-step explanation:
The nurse should report a potassium level of 5.5 mEq/L to the provider. End-stage kidney disease can cause electrolyte imbalances, and a potassium level of 5.5 mEq/L is above the normal range of 3.5-5.0 mEq/L. High potassium levels can be dangerous and may lead to cardiac arrhythmias.
The other lab values mentioned in the options are within the normal ranges. A serum creatinine of 1.2 mg/dL, hemoglobin level of 12 g/dL, and calcium level of 9.0 mg/dL are not alarming in this context.