Pancreatic Functions

Sample for Pancreas

1. The serum of the patient is required.
2. The serum for lipase is stable at room temperature for several days if there is no bacterial contamination.
3. The serum for amylase is stable at room temperature for 7 days and at 4 °C for one month.
4. Urine: Amylase is unstable in acidic urine. Adjust the pH to the alkaline range before storage.
   1. It can take one hour or 24 hours for a urine sample.
   2. Store at 4 °C.

Precautions for Pancreatic Functions tests:

1. Avoid contamination with saliva.
2. Lipemic serum, EDTA, Citrate, and fluoride decrease the Amylase quantity.

Advised Tests for pancreatic functions are:

1. The following blood tests are done to diagnose the pancreatic disease:
   1. Serum amylase
   2. Serum lipase
2. In acute pancreatitis, there is an elevation of amylase and lipase.
   1. Amylase is less specific for pancreatitis than lipase because amylase is also produced by the salivary glands.

Pathophysiology of Pancreas

1. The pancreas weighs 70 to 105 grams and is located in the curve of the duodenum.
   1. The pancreas is the gland with exocrine and endocrine functions that play a very important role in digestive function.
   2. It produces pancreatic juice rich in bicarbonate and digestive enzymes.
   3. Bicarbonate neutralizes acid coming from the stomach.

The pancreas consists of the following:

Endocrine tissue:

1. Islets of Langerhans are small, 0.1 to 0.15 mm in D.
2. Its secretion goes directly into blood circulation. It has no link with the ducts.

Beta cells:

1. These are the most numerous cells which produce insulin.
   1. Insulin is a small protein with a molecular weight of 6000.
   2. Insulin is a potent hormone that promotes glucose uptake and glycogen storage, triglycerides synthesis, and protein synthesis.
   3. It is produced as proinsulin which is inactive.

1. 4. This is known as an antidiabetic hormone.
   5. Insulin’s normal value is 860 pg/mL, which does not exceed this value in a normal person.
   6. While this will increase in the adenoma of the pancreas (Insulinoma).

Alpha cells:

1. It produces glucagon.
2. Glucagon is a polypeptide hormone produced by alpha cells in the islet cells.
   1. Glucagon raises blood sugar by activating the liver phosphorylase, which will break down glycogen.
   2. Glucagon stimulates the hydrolysis of triglycerides in adipose tissue to fatty acids and glycerol.
   3. Glucagon also reduces the secretory response of the parietal cells to all stimuli except histamine.

Exocrine tissue:

1. This produces the digestive enzymes from the acinar cells of the pancreas.

Exocrine enzymes are:

1. Digestive enzymes are:

Amylase:

1. Amylase is a digestive enzyme.
2. Amylase present in human tissue is α- amylase.

3. Amylase breaks down the body’s starch.
4. Alcoholics will raise the level of amylase, which is salivary gland origin.

Lipase

1. Lipase helps to digest fats.
2. This is a glycoprotein with a molecular weight of 54000 and an isoelectric point of about 5.8.
3. Lipase concentration in the pancreas is about 100 times greater than in other tissue.
4. Lipase is technically difficult to measure. But Lipase is not cleared in urine, so it remains in the blood circulation even amylase becomes normal.

Proteolytic enzymes are:

1. Trypsin is a main proteolytic enzyme.
2. Chymotrypsin is secreted as chymotrypsinogen A and B.
3. Collagenase digests collagen and is the enzyme that initiates destruction in necrotizing pancreatitis.
4. Elastase specially digests elastin which is the most resistant of all body proteins to lytic agents.

Peptidases are:

1. Carboxypeptidase removes amino acids one by one from the carboxyl ends of the peptide chain.
2. Aminopeptidase removes the amino acids from the end of peptide chains having a free amino group.

Nucleases are:

1. Ribonuclease.
2. Deoxyribonuclease hydrolyzes the respective nucleic acid.

Normal values

Source 1

Lipase serum

• <200 U/L (with triolein)
• <160 U/L (with olive oil)
• With RIA = <112 µg/L
  • To convert into SI unit x 0.017 = µKat/L

Amylase serum

• Newborn 2 to 4 days = 5 to 65 U/L
• Adult = 27 to 131 U/L
• 60 to 90 year = 24 to 151 U/L
  • To convert into SI unit x  0.017 = µKat/L

Amylase urine

• 1 to 17 U/hour (Beckman)
• 170 to 2000 U/L (Phadebas)
• 5 to 27 U/hour (Abbott TDx)
  • The values vary from different methodologies.

Source 2

Amylase serum

• 60 to 120 Somogyi units/dL (30 to 220 units/L) .
• Newborn = 6 to 65 units/L

Urine amylase 24 hours

• up to 500 Somogyi units.

Lipase  serum

• 0 to 160 units/L

(Values vary according to the method).

• Critical value =  More than three times the normal.

Symptoms of acute Pancreatitis are:

1. There is sudden epigastric pain in 90% to 100% of the patients, which may radiate to any side but mostly to the back.
2. Acute pancreatitis is due to the blockage of pancreatic ducts or direct injury to the pancreatic tissue by:
   1. Toxin.
   2. Inflammation.
   3. Trauma.
   4. Impaired blood flow to the pancreas.
3. Loss of appetite.
4. Nausea and vomiting.  There is vomiting in 30% to 96% of the cases.
5. There is abdominal distension in 70% to 80% and paralytic ileus in 50% to 80% of the cases,
6. Jaundice may be seen in 8% to 30%.
7. Hypotension and shock develop in 30% to 40% of the cases.
8. Diagnosis in typical cases is easy, but similar symptoms may be seen in various diseases.

Diagnosis of acute pancreatitis:

1. For the first few days, check amylase at least twice a day.
2. >500 Somogyi units favor acute pancreatitis.
3. The peak is short and may be missed.

Lipase is increased in:

1. Acute Pancreatitis.

2. Pancreatic cyst or pseudocyst.
3. Pancreatic cancers.
4. Chronic pancreatitis
5. peptic ulcer with perforation of the pancreas.
6. Gastric cancer with perforation of the pancreas.
7. Acute cholecystitis.
8. Certain drugs like deoxycholate and glycocholate.
9. Chronic liver disease

Amylase is increased in:

1. In Acute pancreatitis, it is increased 4 to 6 times normal.
   1. The increase occurs within 4 to 8 hours of the onset.
   2. Remain elevated till the cause is removed.
2. Chronic pancreatitis initially, there is a mild increase and, later on, decrease due to damage to the pancreas.
3. Increased in pancreatic duct obstruction.
4. Pancreatic cancers.