Diaminooxidase activity, DAO

General information:

Diamine oxidase (DAO) is the key enzyme responsible for breaking down histamine.
DAO enzymatically breaks down extracellular (free) histamine, regardless of whether it originates from allergically induced processes in the body or has been ingested with food. Histamine breaks down to imidazole acetaldehyde, which, after methylation to methylhistamine, is excreted by the kidneys. DAO activity determines the rate of histamine degradation. If it is inhibited, histamine accumulates in the blood.
DAO activity and blood histamine concentration can be measured.
DAO is stable and is continuously released into the bloodstream. Its activity in the serum is directly dependent on the body's capacity to break down histamine. Therefore, the enzyme is a suitable marker for the diagnosis of histamine intolerance/HIT/and related diseases.
HIT can develop if histamine ingested with food or released in an allergic reaction is not broken down efficiently enough due to DAO deficiency. Histamine intolerance can also manifest clinically with an excess of histamine that "overpowers" the normal activity of DAO. Allergic conditions such as hay fever or sensitivity to molds and other allergens are additional prerequisites for the release of histamine and can have a cumulative effect, together with histamine taken from food. To determine whether the individual tolerance limit has been exceeded, DAO activity should always be analyzed together with the total blood histamine concentration.

Sample required:

Venous blood

Key words:

DAO, diaminooxidase activity, histamine