From the Guidelines
Elevated chloride and amylase levels are indicative of potential pancreatic inflammation or injury, and acute pancreatitis should be considered as the primary concern, with further investigation and management guided by the most recent and highest quality evidence, such as the 2019 WSES guidelines for the management of severe acute pancreatitis 1. When evaluating these laboratory findings, it's crucial to consider the clinical context and potential causes. Elevated chloride levels (hyperchloremia) may indicate dehydration, kidney dysfunction, or metabolic acidosis, with common causes including diarrhea, certain medications, or hyperparathyroidism. On the other hand, elevated amylase levels most commonly point to pancreatic inflammation or injury, but can also be associated with salivary gland disorders, intestinal obstruction, or kidney problems.
Key Considerations
- The diagnosis of acute pancreatitis is typically supported by serum pancreatic enzyme measurement, with lipase being considered a more reliable diagnostic marker than amylase due to its higher sensitivity and larger diagnostic window 1.
- The 2019 WSES guidelines recommend a cut-off value of serum amylase and lipase to be three times the upper limit for diagnosis, and suggest that C-reactive protein level ≥ 150 mg/l at the third day can be used as a prognostic factor for severe acute pancreatitis 1.
- Procalcitonin is considered the most sensitive laboratory test for detection of pancreatic infection, and low serum values appear to be strong negative predictors of infected necrosis 1.
Management and Treatment
- Management depends on identifying the underlying cause through additional tests like lipase levels, comprehensive metabolic panel, and imaging studies.
- Treatment typically addresses the primary condition rather than the laboratory abnormalities themselves, often including IV fluids, pain management, and specific interventions for the diagnosed condition.
- In the absence of gallstones or significant history of alcohol use, serum triglyceride and calcium levels should be measured, with serum triglyceride levels over 11.3 mmol/l (1000 mg/dl) indicating it as the etiology 1.
From the Research
Elevated Chloride and Amylase
- Elevated serum levels of amylase and lipase are often encountered in clinical practice, with a broad differential diagnosis including acute pancreatitis, chronic pancreatitis, gastrointestinal tract obstruction, malignancies, and other disease conditions 2.
- Serum amylase and lipase levels are not specific for pancreatitis, and attempts have been made to validate newer biomarkers for the diagnosis of acute pancreatitis 3.
- Serum lipase offers a higher sensitivity than serum amylase in diagnosing acute pancreatitis, and has a larger diagnostic window, making it a useful diagnostic biomarker in early and late stages of acute pancreatitis 4.
Diagnostic Approaches
- The diagnosis of acute pancreatitis is usually based on the presence of abdominal pain and elevated levels of serum amylase and/or lipase, with a threshold concentration 2-4 times the upper limit of normal recommended for diagnosis 5.
- Serum lipase is now the preferred test due to its improved sensitivity, particularly in alcohol-induced pancreatitis, and its prolonged elevation creates a wider diagnostic window than amylase 5.
- The co-ordering of both amylase and lipase tests has shown little to no increase in the diagnostic sensitivity and specificity, and unnecessary testing and laboratory expenditures can be reduced by testing lipase alone 4.
Limitations of Current Tests
- About a quarter of people with acute pancreatitis fail to be diagnosed as having acute pancreatitis with the evaluated tests, and about 1 in 10 patients without acute pancreatitis may be wrongly diagnosed as having acute pancreatitis with these tests 6.
- The diagnostic performance of these tests decreases even further with the progression of time, and additional investigations should be considered if the symptoms are suggestive of acute pancreatitis 6.