Amyloid is a misfolded form of a protein. Most proteins can form amyloid under the right conditions.

The diseases linked to amyloid are the amyloidoses. They can be specific (eg, production of Abeta in the brains of people with Alzheimer's Disease) or systemic (the amyloid is from a blood protein and so can affect different tissues).

Some dyes like Congo Red and Thioflavin T change their optical properties when they bind to amyloid; amyloid levels can be measured from this.

This is usually followed up with specific clinical investigations relevant to a given amyloidosis.