A 65-year-old man who had a 25-lb weight loss over the previous 6 months is diagnosed with adenocarcinoma of the distal esophagus. He undergoes a transhiatal esophagectomy complicated by a cervical leak. He is receiving enteral feeds through a jejunostomy tube. After a week, his physicians wish to assess his nutritional resuscitation. Which of the following is the most accurate measure of adequacy of his nutritional suppo?

**Core Concept**
The question is testing the understanding of nutritional assessment in critically ill patients, specifically the measurement of nutritional adequacy in patients receiving enteral nutrition through a jejunostomy tube.

**Why the Correct Answer is Right**
The most accurate measure of nutritional adequacy in this scenario is the **Nitrogen Balance (NB)**. Nitrogen balance is calculated as the difference between nitrogen intake and nitrogen excretion. A positive nitrogen balance indicates that the patient is in a state of nitrogen retention, which is a sign of adequate nutritional support. In critically ill patients, a positive nitrogen balance is a better indicator of nutritional adequacy than other measures such as albumin levels or prealbumin, as these can be influenced by various non-nutritional factors.

**Why Each Wrong Option is Incorrect**
**Option A:** Serum albumin levels are not a reliable measure of nutritional adequacy in critically ill patients, as albumin levels can be influenced by factors such as inflammation, liver disease, and fluid status.
**Option B:** Prealbumin levels, while a more sensitive indicator of nutritional status than albumin, are still not a direct measure of nutritional adequacy and can be influenced by non-nutritional factors.
**Option C:** Weight gain is not a reliable measure of nutritional adequacy, as it can be influenced by factors such as fluid retention and edema.

**Clinical Pearl / High-Yield Fact**
Nitrogen balance is a useful measure of nutritional adequacy in critically ill patients, but it requires careful calculation and consideration of individual patient factors. A positive nitrogen balance of 5-10 grams per day is generally considered a good indicator of adequate nutritional support.

**Correct Answer: C. Nitrogen balance**

✓ Correct Answer: C. Serum albumin level