Lipase Serum

sample

1. The venous blood is needed to prepare the serum.
2. EDTA or citrated plasma interfere with the result.
3. The serum is stable at room temperature for several days.
4. Can refrigerate the sample or freeze it.
5. A fasting sample is not important.
6. Pleural fluid and ascitic fluid can be used for pancreatic diseases.

Precaution

1. 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.

Important facts:

1. The lipase is specific for pancreatitis and is not like amylase.
2. The level of lipase is parallel with a raised level of amylase but it remains elevated up to 14 days.
3. Lipase is considered superior to amylase for the diagnosis of pancreatitis.

Precautions

1. There are certain drugs that increase the level are, Codeine, Indomethacin, Cholinergic, and Morphine.
2. There are certain drugs that decrease the level is calcium ions.

Pathophysiology

1. Lipase is a glycoprotein (Triacylglycerol acyl hydrolase) and has enzymatic activity.
   1. Its molecular weight is 54000.
   2. The lipase gene resides on chromosome 10.
   3. The concentration gradient between the pancreas and serum is ∼20,000 folds.
   4. The major source of Lipase is the pancreas (100 times greater than the other tissues) and from there it enters the duodenum.
2. Lipase changes fats (triglycerides)  to fatty acids and glycerol in the presence of bile salt.

3. Lipase appears in the blood due to damage to the pancreas. At the same time, Amylase also appears.
   1. Lipase lasts longer than Amylase (7 to 10 days).
4. There are other sources of the lipase-like enzyme in the kidney, where there will be an increased lipase level in renal failure.

5. Intestinal infarction or obstruction may be associated with the raised level of lipase.
6. Lipase raised in pancreatitis 5 to 10 times the normal value while in non-pancreatic diseases this value is less.
   1. In acute pancreatitis, the lipase level is parallel to the amylase level.
   2. It’s raised level is parallel to the amylase level but it may remain elevated up to 14 days (second source).
7. The lipase level is better in the late diagnosis of pancreatitis.
8. Lipase level is less useful in chronic pancreatic diseases like chronic pancreatitis, and pancreatic carcinoma.
9. Lipase or colipase enzyme may be completely absent congenitally and result in steatorrhea.
10. Acute pancreatitis produces ascitic fluid and pleural fluid (more on the left side but maybe both pleural cavities).
    1. There is lipase activity in these fluids.
11. 50% develop pseudocyst. This should be suspected when there is no improvement after the treatment within a week of the attack.
12. Differential diagnosis of acute pancreatitis from:
    1. Perforated gastric ulcer.
    2. Perforated duodenal ulcer.
    3. Mesenteric vascular obstruction.
    4. Intestinal obstruction.
       1. Lipase activity is more helpful than amylase in these conditions.

Normal

Source 1

• <200 U/L (with triolein)
• <160 U/L (with olive oil)

Another source

• 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:

1. Markedly increased level seen in Acute pancreatitis after 3 to 6 hours of onset.
2. Chronic pancreatitis, pancreatic trauma, pancreatic carcinoma and obstruction of the pancreatic duct.
3. Intestinal obstruction and infarction.
4. Acute cholecystitis due to stones.
5. Primary biliary cirrhosis.
6. Acute cholangitis.
7. Salivary gland inflammation or obstruction.
8. Chronic renal failure.
9. Peptic ulcer disease.
10. Peritonitis.
11. Hemodialysis.

Acute pancreatitis Diagnosis

1. Lipase remains elevated for a longer period than the Amylase, so greater sensitivity even in the patient who come late for the consultation.
2. The lipase level rises after the Amylase. But both are parallel to each other in values. Lipase increase is greater to amylase.
   1. Raised level of amylase does not parallel the severity of pancreatitis.
3. Lipase rises after 4 to 8 hours after the onset of pancreatitis.
   1. The peak level is at 48 hours.
   2. Lipase may remain elevated up to 14 days while Amylase not.
   3. Lipase decreases between 8 to 14 days.
   4. This may increase from 2 to 5o times of the normal value.
4. Amylase may be elevated in other abdominal pathology and renal insufficiency.
5. Hypertriglyceridemia does not interfere with the estimation of Lipase.
6. Normal lipase level is seen in 20% of the cases of acute pancreatitis.

---