Pancratic function tests

PACREATIC FUNCTION TESTS

  • The pancreas has two main functions.  
    • Exocrine function     
    • Endocrine function.
  • The endocrine functions involving the secretions of insulin and glucagon are related to carbohydrate metabolism. 
  • The exocrine functions involve the synthesis and secretion digestive enzyme trypsin,chymotrypsin, lipase etc..

Serum amylase

  • The principal in the use of serum amylase  estimation is that this enzyme hydrolyzes starch into maltose and dextrins. There are two general methods of measurement.
    • The rate of disappearance of starch ( amyloclastic ) 
    • The rate of appearance of reducing sugars ( saccharogenic)

Serum lipase 

  • The pancreas is the major source of lipase, which catalyzes the hydrolysis of triacylglycerol to fatty acids and glycerol. 
  • In pancreatitis there is an increase in the activity of serum amylase and lipase.

Fat absorption

  • Absorbance of fat is impaired.
  • Staining the stools with sudan red for fat droplets.
  • Stools from some patients with pancreatitis show a marked increase in neutral fat, because of the absence of pancreatic lipase.
  • This enzyme hydrolyses dietry fat into fatty acid and glycerol before absorption.
  •  To conduct this test, the animal is fasted and the blood sample is taken from the fasted animal. A meal rich in digestible oils such as corn or peanut oil is fed to the animal and the blood sample is collected 3h later. The samples are centrifuged and the turbidity of the samples is compared.
  • A normal dog, the plasma of the sample taken before the administration of the test meal is clear, whereas the post feeding sample will be turbid due to lipemia. A dog with a deficiency of pancreatic lipase or with malabsorption will  show clear plasma or serum. The two conditions can be differentiated by giving a fat meal along with commercial pancreatic lipase. In pancreatic lipase deficiency, lipemia is  produced when enzyme is added, this indicates that absorption from the small intestine is normal. In malabsorption even after the addition of enzyme, lipemia does not occur due to intestinal block, which interferes with absorption.

Pancreatic chymotrypsin activity

  • This test is based on the principle that pancreatic juice contains chymotripsin, which releases p-aminobenzoic acid form N-benzoyl-L-tyrosyl-p-aminobenzoic acid (BT-PABA). This synthetic peptide is given orally. The PABA is absorbed from the gut and excreted in urine, which is measured. The values are compared to normal dog. To eliminate extrapancreatic factors, the BT-PABA is given with a tracer quantity of  14 C labeled PABA and the amount of PABA and 14 C excreted are measured and expressed as ratio of doses given.

Pancreolauryl test

  • This test is based on the principle that fluorescein dilaurate, administered orally, is hydrolyzed in the gut by pancreatic esterase. The water soluble fluorescein is absorbed and excreted in urine, where it can be measured.

Lundh test

  • Pancreatic secretion is stimulated by  giving a test meal containing corn oil, skimmed milk powder and dextrose. The duodenal contents are collected for a period of 2h. the activity of pancreatic enzymes such as trypsin or amylase activity is measured. Decreased activity is noticed in pancreatic disease.

Secretin test

  • An intravenous injection of secretin  stimulates  pancreatic secretions. This is assessed by aspiration of duodenal contents and measurement of trypsin and amylase activity.

Serum trypsin like immunoreactivity

  • The determination of serum TLI level is reliable exocrine pancreatic insufficiency of dog, which develops due to insufficiency of pancreatic digestive enzymes. A decrease in the level of TLI is noted in dog with EPI.
Last modified: Wednesday, 14 December 2011, 7:37 AM