What is a primary indication for parenteral nutrition (PN)?

Parenteral nutrition (PN) is primarily indicated in cases where the gastrointestinal (GI) tract is either inaccessible or non-functional. This means that the patient cannot properly absorb nutrients through the traditional digestive process, which can occur due to various medical conditions such as bowel obstruction, severe pancreatitis, short bowel syndrome, or post-surgical complications where feeding through the GI tract is not feasible.

In such situations, providing nutrition through an intravenous route becomes essential to meet the patient's metabolic needs and ensure they receive the necessary nutrients (like carbohydrates, proteins, fats, vitamins, and minerals) directly into the bloodstream. This approach helps prevent malnutrition and promotes recovery in patients who cannot utilize their digestive system.

The other options do not represent appropriate indications for parenteral nutrition. A functional GI tract would typically allow for enteral feeding, dietary restrictions may be managed through careful planning of oral or enteral nutrition, and sufficient nutrient intake through enteral nutrition indicates that PN is unnecessary. Thus, the indication for PN is fundamentally tied to the inability to utilize the GI tract effectively.