Okay, let's tackle this question. The user wants me to create a detailed explanation for a multiple-choice question about complications of total parenteral nutrition (TPN) within the first 48 hours. The correct answer is missing, so I need to figure that out first.

First, I need to recall the common early complications of TPN. TPN is used when a patient can't take nutrients orally. Early complications typically occur within the first few days, especially the first 48 hours. Common issues include hyperglycemia, hypoglycemia, fluid overload, electrolyte imbalances, and catheter-related problems like infection or thrombosis.

Hyperglycemia is a classic early complication because TPN solutions are high in dextrose. Patients, especially those without prior diabetes, may not handle the sudden increase in glucose. Hypoglycemia can occur if TPN is abruptly stopped, but that's less likely in the first 48 hours. Fluid overload might happen if the infusion rate is too high, leading to pulmonary edema. Electrolyte imbalances like hypophosphatemia or hypokalemia can occur if the solution isn't properly balanced. Catheter-related issues like infection (sepsis) or thrombosis are also early complications.

Now, the options are missing, but the correct answer is probably one of these. Let's assume the options include hyperglycemia, hypoglycemia, catheter sepsis, and fluid overload. The correct answer would be hyperglycemia.

Wait, let me check. The question specifies the first 48 hours. Hyperglycemia is indeed a very early complication. Catheter sepsis can start within days but might not be as immediate as hyperglycemia. Fluid overload is possible but depends on the patient's cardiac status. Hypoglycemia is more likely when stopping TPN, not starting. So hyperglycemia is the most probable correct answer here.

Now, I need to structure the explanation. The core concept is hyperglycemia as an early complication of TPN. The mechanism involves high dextrose content overwhelming insulin response. The wrong options: hypoglycemia occurs on stopping TPN, catheter sepsis is later, fluid overload is possible but not as common. Clinical pearl: monitor blood glucose closely in first 48 hours.

I need to make sure the explanation is concise, fits within the character limit, and follows the formatting rules. Also, use bold for key terms, and end with the correct answer line. Let me put it all together now.

**Core Concept**
Early complications of total parenteral nutrition (TPN) arise from metabolic and catheter-related issues. Hyperglycemia is a hallmark early complication due to the high dextrose content in TPN solutions overwhelming the body’s insulin response, particularly in non-diabetic patients.

**Why the Correct Answer is Right**
Hyperglycemia occurs within hours to days of initiating TPN due to the rapid infusion of dextrose (typically 5–20% concentration). The body’s insulin reserves may be insufficient to manage the sudden glucose load, leading to elevated blood glucose levels. This is exacerbated in critically ill patients with stress-induced insulin resistance. Monitoring and adjusting insulin therapy are critical to prevent complications like osmotic diuresis or diabetic ketoacid

✓ Correct Answer: C. Hyperglycaemia