Final answer:
The nurse should report low phosphorus levels to the provider as it can lead to hypophosphatemia, causing muscle weakness, bone pain, and fatigue.
Step-by-step explanation:
The nurse should report the lab result of low phosphorus levels to the provider. When a patient is receiving continuous Total Parenteral Nutrition (TPN), monitoring electrolyte levels is crucial. Low phosphorus levels can lead to a condition called hypophosphatemia, which can cause muscle weakness, bone pain, and fatigue.