**Core Concept**
Acute pancreatitis is a complex clinical condition characterized by inflammation of the pancreas, leading to various systemic complications. The prognosis of acute pancreatitis can be influenced by several key factors, including electrolyte imbalances, glucose metabolism, and calcium levels.

**Why the Correct Answer is Right**
Hyperglycemia (elevated blood glucose levels) is associated with poor prognosis in acute pancreatitis due to its potential to exacerbate pancreatic inflammation and contribute to multi-organ dysfunction. This is because hyperglycemia can lead to increased insulin resistance, oxidative stress, and activation of pro-inflammatory cytokines, ultimately worsening the clinical outcome. Additionally, hyperglycemia can also impair the immune response, making patients more susceptible to infections.

**Why Each Wrong Option is Incorrect**
**Option A:** Hypocalcemia (low calcium levels) is actually a common feature of acute pancreatitis due to the saponification of calcium in the fat necrosis process. While severe hypocalcemia can be a concern, it is not directly associated with poor prognosis.

**Option B:** Hypercalcemia (elevated calcium levels) is not typically associated with acute pancreatitis. In fact, hypocalcemia is more commonly seen due to the reasons mentioned above.

**Option C:** Hypernatremia (high sodium levels) is not a specific indicator of poor prognosis in acute pancreatitis. While electrolyte imbalances are common in this condition, hypernatremia is not as directly related to prognosis as hyperglycemia.

**Clinical Pearl / High-Yield Fact**
In acute pancreatitis, the presence of hyperglycemia should prompt immediate attention to glucose management, as controlling blood glucose levels can help mitigate the severity of the condition and improve patient outcomes.

**Correct Answer: D. Hyperglycaemia**