- The venous blood is needed to prepare the serum.
- EDTA or citrated plasma interfere with the result.
- The serum is stable at room temperature for several days.
- Can refrigerate the sample or freeze it.
- A fasting sample is not important.
- Pleural fluid and ascitic fluid can be used for pancreatic diseases.
- Hemolysis will inhibit lipase activity.
Purpose of the test (Indications):
- Advised to diagnose acute pancreatitis.
- Advised to monitor the treatment of acute pancreatitis.
- It differentiates pancreatitis from other causes of acute abdomen.
- The lipase is specific for pancreatitis and is not like amylase.
- The level of lipase is parallel with a raised level of amylase but it remains elevated up to 14 days.
- Lipase is considered superior to amylase for the diagnosis of pancreatitis.
- There are certain drugs that increase the level are, Codeine, Indomethacin, Cholinergic, and Morphine.
- There are certain drugs that decrease the level is calcium ions.
- Lipase is a glycoprotein (Triacylglycerol acyl hydrolase) and has enzymatic activity.
- Its molecular weight is 54000.
- The lipase gene resides on chromosome 10.
- The concentration gradient between the pancreas and serum is ∼20,000 folds.
- The major source of Lipase is the pancreas (100 times greater than the other tissues) and from there it enters the duodenum.
- Lipase changes fats (triglycerides) to fatty acids and glycerol in the presence of bile salt.
- Lipase appears in the blood due to damage to the pancreas. At the same time, Amylase also appears.
- Lipase lasts longer than Amylase (7 to 10 days).
- There are other sources of the lipase-like enzyme in the kidney, where there will be an increased lipase level in renal failure.
- Intestinal infarction or obstruction may be associated with the raised level of lipase.
- Lipase raised in pancreatitis 5 to 10 times the normal value while in non-pancreatic diseases this value is less.
- In acute pancreatitis, the lipase level is parallel to the amylase level.
- It’s raised level is parallel to the amylase level but it may remain elevated up to 14 days (second source).
- The lipase level is better in the late diagnosis of pancreatitis.
- Lipase level is less useful in chronic pancreatic diseases like chronic pancreatitis, and pancreatic carcinoma.
- Lipase or colipase enzyme may be completely absent congenitally and result in steatorrhea.
- Acute pancreatitis produces ascitic fluid and pleural fluid (more on the left side but maybe both pleural cavities).
- There is lipase activity in these fluids.
- 50% develop pseudocyst. This should be suspected when there is no improvement after the treatment within a week of the attack.
- Differential diagnosis of acute pancreatitis from:
- Perforated gastric ulcer.
- Perforated duodenal ulcer.
- Mesenteric vascular obstruction.
- Intestinal obstruction.
- Lipase activity is more helpful than amylase in these conditions.
- <200 U/L (with triolein)
- <160 U/L (with olive oil)
- Adult = 10 to 140 U/L.
- Elderly >60 years = 18 to 180 U/L.
- (Values vary from lab to lab. and depends upon method).
Increased Lipase level is seen in:
- Markedly increased level seen in Acute pancreatitis after 3 to 6 hours of onset.
- Chronic pancreatitis, pancreatic trauma, pancreatic carcinoma and obstruction of the pancreatic duct.
- Intestinal obstruction and infarction.
- Acute cholecystitis due to stones.
- Primary biliary cirrhosis.
- Acute cholangitis.
- Salivary gland inflammation or obstruction.
- Chronic renal failure.
- Peptic ulcer disease.
Acute pancreatitis Diagnosis
- Lipase remains elevated for a longer period than the Amylase, so greater sensitivity even in the patient who come late for the consultation.
- The lipase level rises after the Amylase. But both are parallel to each other in values. Lipase increase is greater to amylase.
- Raised level of amylase does not parallel the severity of pancreatitis.
- Lipase rises after 4 to 8 hours after the onset of pancreatitis.
- The peak level is at 48 hours.
- Lipase may remain elevated up to 14 days while Amylase not.
- Lipase decreases between 8 to 14 days.
- This may increase from 2 to 5o times of the normal value.
- Amylase may be elevated in other abdominal pathology and renal insufficiency.
- Hypertriglyceridemia does not interfere with the estimation of Lipase.
- Normal lipase level is seen in 20% of the cases of acute pancreatitis.