Which nutrient is a primary component of total parenteral nutrition?

• A. Protein
• B. Glucose
• C. Lipids
• D. Electrolytes

Answer: (B)

In total parenteral nutrition, the body’s energy is supplied primarily by a carbohydrate source delivered intravenously. Dextrose, a form of glucose, is the main energy substrate in most TPN formulations. While amino acids provide the building blocks for tissue repair and growth, and lipids deliver calories along with essential fatty acids, none of these match glucose as the primary energy source. Electrolytes are essential for fluid and metabolic balance, but they do not provide energy. Therefore, glucose stands out as the primary component because it supplies the largest portion of calories in the solution, supporting overall energy needs and sparing protein from being used for energy.