Alpha-Amylase (Salivary Isoform)
Definition
An enzyme present in saliva at concentrations several orders of magnitude higher than in other body fluids. Detected immunologically using anti-human salivary amylase antibodies. Used as a confirmatory marker for saliva in forensic casework, including biting cases and oral sexual assault.
- Detection method
- Immunoassay with anti-salivary-amylase antibody
- Test category
- Confirmatory, not presumptive
- Typical casework use
- Bite marks, oral sexual assault
- Distinguishes from
- Pancreatic amylase isoform
Common questions
Why is an isoform-specific antibody needed rather than a general amylase test?+
Amylase exists in salivary and pancreatic isoforms that differ slightly in structure, and a general enzymatic test cannot tell them apart. An antibody raised against the salivary isoform specifically confirms a salivary source rather than incidental amylase from another body fluid.
How does this test complement the Phadebas or starch-iodine screen?+
The Phadebas and starch-iodine tests are fast presumptive screens run on the whole scene item, while the immunological isoform test is applied afterward to a positive area to confirm the source is genuinely saliva before that result is reported evidentially.
Related terms
- Inhibition Agglutination Assay
- A serological technique for detecting soluble antigens in body-fluid extracts. Known antibody is incubated with the stain extract; if the target antigen...
- Lateral-Flow Immunochromatographic Strip
- A point-of-care format immunoassay in which a sample migrates along a nitrocellulose membrane past a labelled antibody zone and a capture antibody...
- Prostate-Specific Antigen (PSA)
- A serine protease glycoprotein (also called p30) secreted in high concentrations by the prostate gland into seminal plasma. The primary immunological marker...
- Secretor
- An individual whose ABO blood group antigens are expressed on red blood cells and also released into body fluids such as saliva,...
- Sexual Assault Forensic Examination (SAFE) Kit
- The standardised collection kit used by trained healthcare providers to obtain biological samples from a survivor within a defined collection window, typically...