Which of the following is the most sensitive serum marker for acute pancreatitis in the first 24 hours?

Explanation

## Serum Markers in Acute Pancreatitis **Key Point:** Serum lipase is the most sensitive and specific marker for acute pancreatitis, particularly within the first 24 hours of symptom onset. ### Comparison of Diagnostic Markers | Marker | Sensitivity | Specificity | Peak Time | Duration | Notes | |--------|-------------|-------------|-----------|----------|-------| | **Serum Lipase** | 95–100% | 95–99% | 24–72 hrs | 8–14 days | Gold standard; more specific than amylase | | **Serum Amylase** | 85–100% | 85–98% | 24–48 hrs | 3–7 days | Less specific; rises and falls faster | | **Pancreatic Phospholipase A2** | 90–95% | 95–98% | Early | Shorter duration | Research marker; not routine | | **Procalcitonin** | Variable | Variable | 24–48 hrs | Variable | Marker of severity/infection, not diagnosis | **High-Yield:** Lipase remains elevated for 8–14 days, making it superior for late presentations (>72 hours). Amylase is cleared faster and may be normal in chronic pancreatitis. ### Clinical Pearl **Tip:** A three-fold elevation above the upper limit of normal in either lipase or amylase, combined with characteristic clinical features, is diagnostic of acute pancreatitis [cite:Harrison 21e Ch 297]. ### Why Lipase Wins 1. **Pancreatic specificity:** More specific to pancreas than amylase (which is also produced by salivary glands, small bowel, and other tissues). 2. **Longer window:** Remains elevated longer, catching late presentations. 3. **Single test suffices:** Amylase adds little diagnostic value if lipase is done. **Warning:** Do not rely on amylase alone — it can be normal in up to 10% of acute pancreatitis cases, especially in hypertriglyceridemia-induced pancreatitis.