Final answer:
The prealbumin level of 30 mg/dL indicates effective TPN therapy.
Step-by-step explanation:
The laboratory finding that indicates effective total parenteral nutrition (TPN) therapy is a prealbumin level of 30 mg/dL. Prealbumin, also known as transthyretin, is a protein that is synthesized in the liver and has a short half-life. It serves as a marker for nutritional status and liver function.
Calcium, hemoglobin, and cholesterol levels are not directly related to TPN therapy effectiveness. Calcium level is within the normal range, and hemoglobin and cholesterol levels are not specific indicators of TPN therapy effectiveness.