Clinical Significance of "Amylase"

1. Clinical significance of Amylase

2. • Amylase: catalyzes hydrolysis of amylopectin, amylase,
glycogen, starch & their partially hydrolyzed products.
• It doesn’t attack α-1,6-linkage at branch points

3. • Amylase: Ca-metalloenzyme. [Ca absolutely req. for
functional integrity]
• Also needs different anions (allosteric activator) for its
optimal activity. [Cl-, HPO4
--, Cholate, Br-, NO3
-]
• Optimum pH: 6.9 – 7.0

4. • Amylase: only plasma enzyme normally found in urine.
– Mol. wt: 54000-62000 [Small enough to pass through
glomeruli of kidney]

5. • Types:-
– α-Amylase [Animal]
– -Amylase [Bacteria, Plant]
– γ-amylase [Fungi]
• α-amylase is of clinical interest.

6. • α amylase
– endoenzyme
– occurs in animal tissue & fluid.
– It splits α-1,4-glucosidic bonds in polysaccharides
containing three or more α-1,4- linked D-glucose units
in random fashion.
Hydrolytic products
Starch Amylase + Amylopectin
Amylose Maltose + Glucose
Amylopectin Mixture of branched & unbranched oligosaccharides

7. • α-amylase is stable:
At RT for at least 1 week
When refrigerated For at least 6 months
When kept in frozen state Much longer time

8. • α-amylase undergo post-translational modification to
form no. of isoenzymes.
– Deamidation
– Glycosylation
– Deglycosylation
• “S” type & “P” type
• Can be separated in both serum & urine by
Electrophoresis.

9. • α-amylase is normally present in:
Pancreas Blood Brain
Salivary glands Urine Lung
Liver Feces Fallopian tube
Muscle Milk Intestine
Adipose tissue Semen Spleen
Saliva Kidney Heart

10. CLINICAL SIGNIFICANCE
• Blood amylase activity is normally low & constant.
• S. Amylase:
– Normal level: 60-150 So/dL
• 1 Somogyi Unit: amount of enzyme req. to
hydrolyse 5mg of starch at specific condition [pH
7.0, 37◦C, 15min].

11. • S. Amylase ↑es in;-
– Acute pancreatitis [“P” type]
– Salivary gland inflammation [“S” type]

12. • Specificity of amylase is low since hyperamylassemia
occurs in no. of condition.
Other intraabdominal
disorder
[P-type]
Genito Urinary Disease
[S-type]
Miscellaneous
[S-type]
Biliary tract disease Ruptured ectopic
pregnancy
Salivary Gland lesions
Intestinal obstruction Salpingitis Acute alcoholic abuse
Mesenteric infarction Ovarian malignancy DKA
Perforatic peptic ulcer Renal insufficiency [Mixed] Septic shock
Gastritis Cardiac surgery
Duodenitis Tumours of lungs
Acute appendicitis
perotinitis

13. Amylase & Lipase in Acute Pancreatitis
Starts to ↑ Peak Back to normal
Amylase 5-8hrs 12-72hrs 3rd - 5th day
Lipase 4-8hrs 24hrs 8th – 14th day

14. • S. Amylase in Acute pancreatitis
– Magnitude of elevation isn’t related to severity of
pancreatic involvement.
• Higher magnitude ↑es probability of acute
pancreatitis.
• Normal amylase level can’t rule out the probability of
acute pancreatitis.

15. • Urine amylase
– ↑ in S. amylase → Clearance via excretion through
Kidney → ↑ in U. Amylase
– Urinary Amylase increases on 1st day & remains to be
elevated for 7-10 days.

16. • Amylase to Creatinine ratio
=
• Normal ratio=1-4%
– ↑es in Acute pancreatitis
– ↓es in Macroamylassemia
U.Amylase
--------------- X
S.Amylase
S. Creatinine
--------------------- X 100
U. Creatinine

17. • MACROAMYLASEMIA
– Hyperamylasemia with no apparent clinical symptoms.
– Conditions associated:
• Lymphoma
• Monoclonal gammopathy
• Rheumatoid arthritis
Amylase complexed to IgA / IgG (mostly) or Polysaccharides (rarely)
↓
Forms macroamylase
↓
Can’t excreted via urine
↓
Accumulated in blood
↓
Macroamylasemia

18. Lipase
• Single chain glycoprotein
• Attacks ester bond at C1 & C3 →Hydrolyses glycerol
esters of long chain FA
• Bile salt, Colipase, Optimal pH 8.8, Optimal temp. 40°C
req for optimal activity of enzyme.

19. • Lipase concentration in pancreas is
– ~ 5000 folds greater than in any other tissue,
– ~ 20000 folds greater than in serum.
– Thus, S. Lipase is more specific marker for acute
pancreatitis than S. Amylase.

20. Acute Pancreatitis Chronic Pancreatitis
Amylase ↑ ↓
Lipase ↑ ↓