AMYLASE!!!

"did you know that the organ that secretes most amylaze isnt the pancreas, but the salivary gland! (about 6:4)"

"only 75% of acute pancreatitis had hyperamylasaemia"

About amylaze
It is secreted mainly by pancreas and saliva (significantly large amounts)
2 main types of amylaze:
- P type from pancreas
- S type from salivary glands
(S type is also found in tears, breast milk, sweat, testes, fallopian tube etc. but Salivary gland = major contributor)

Clearance of amylaze:
- Renal: nephrectomy patients have 50% higher amylaze levels
- Extrarenal: currrently unknown, probably hepatic: people with hepatic necrosis have raised amylase (both S and P type)too

Causes of hyperamylasaemia can be subdivided into:
1. pancreatitis/parotitis
2. decreased metabolic clearance (liver/renal pathologies)

Discussion of common causes:
Pancreatitis:
- Causes: I GET SMASHED: idiopathic, mumps, autoimmune, scorpion, ERCP, drugs (SAND) and duodenal ulcers
- History: epigastric pain radiating to the back, relieved on sitting up and leaning forward and severe N and V
- S/S: Steatorrhea, Cullen's sign, Grey-Turner's sign
- Test: lipase, amylaze raised 4x on day of presentation (electrophoresis shows P type). Imaging (CT, A U/S)
interesting notes:
(i) 3-4x increased in amylaze 4 hours after ERCP = predictive of post procedural pancreatitis
(ii) 3x increased amylaze with biliary colic = passage of stones through bile duct

Prognostication: RANSON's criteria: GA LAW at presentation, C Hobbs (calvin and hobbs) at 48 hours
- Glucose
- Age >55
- Lipase
- AST
- WBC

- calcium

- Ht

- O2 arterial

- BUN

- Base deficit

- Sequestration of fluid

Other causes of raised amylase:
1. salivary disease
2. decreased metabolic clearance (hepatic and renal disease) - both S and P are increased
3. Macroamylasaemia (amylze binds to larger molecules to form complexes, prolonging its Thalf and reducing renal excretion)
4. Intestinal disease: P amylase is raised as intestinal diseases result in increased absorption of amylaze. in the case of perforated viscus, there is increased reabsorption of amylase via peritoneal lining.
5. Gynaecological causes
6. AAA (p type)
7. pneumonia (S type)

how to differentiate acute pancreatitis from the others?
- chronic hyperamylasaemia is almost never acute pancreatitis
- ACR = (amy[urine] x creat[serum])/(amy[serum] x creat [urine]) x 100. an ACR > 5% = pancreatitis or DKA