Diamine Oxidase
Private Diamine Oxidase blood test in London for £99, measuring DAO activity with specialist results expected in approximately 2 weeks.
Turnaround time
2 weeks
Biomarkers count
1
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Overview of the Diamine Oxidase
The Diamine Oxidase blood test measures Diamine Oxidase Activity, commonly abbreviated to DAO.
The test contains 1 biomarker: Diamine Oxidase Activity.
Diamine Oxidase is an enzyme involved in the breakdown of histamine, particularly histamine encountered within the gastrointestinal tract from food.
Histamine is a naturally occurring signalling molecule involved in immune responses, stomach-acid regulation, blood-vessel function and nervous-system activity. It is also present in varying amounts in fermented, aged and stored foods.
DAO is produced predominantly within the intestinal mucosa and contributes to the metabolism of extracellular histamine before excessive amounts enter the circulation.
Reduced DAO activity has been proposed as one potential mechanism contributing to histamine intolerance, a term used for symptoms that appear to occur when histamine exposure exceeds an individual's capacity to metabolise it.
Possible symptoms attributed to histamine intolerance include flushing, headaches, nasal symptoms, gastrointestinal discomfort, diarrhoea, palpitations and skin reactions.
However, histamine intolerance remains a complex and incompletely standardised clinical diagnosis.
A low serum DAO result does not independently prove that histamine is causing symptoms, and there is no universally accepted blood-test threshold that can diagnose histamine intolerance in every patient.
DAO activity can also be influenced by gastrointestinal disease, medication, nutritional factors and individual biological variation.
Symptoms attributed to histamine intolerance overlap extensively with food allergy, irritable bowel syndrome, mast-cell disorders, migraine, medication effects and other gastrointestinal or allergic conditions.
The result should therefore be interpreted alongside the dietary history, symptom pattern and other investigations where clinically appropriate.
What Does the Diamine Oxidase Test Check?
This test measures 1 biomarker.
Diamine Oxidase Activity
Measures the activity of the DAO enzyme involved in breaking down extracellular and dietary histamine, providing supplementary information where impaired histamine metabolism is being investigated.
Who May Benefit From the Diamine Oxidase Test?
DAO testing may be considered where symptoms repeatedly appear after foods containing or releasing substantial amounts of histamine.
People with reproducible symptoms after histamine-rich foods - A clear and repeated relationship between particular foods and symptoms can make specialist assessment more meaningful.
People with flushing after fermented or aged foods - Histamine can affect blood vessels and may contribute to flushing in susceptible individuals.
People with recurrent gastrointestinal symptoms linked to particular foods - Abdominal discomfort, diarrhoea or bloating may be reported, although these symptoms have many other causes.
People with unexplained headaches after certain foods or alcohol - Histamine has been proposed as one trigger in susceptible individuals.
People with suspected histamine intolerance after other conditions have been considered - DAO testing may provide supplementary information rather than acting as a standalone diagnostic test.
People with gastrointestinal disease affecting the intestinal lining - DAO is produced within intestinal mucosa, so significant intestinal disease may influence enzyme activity.
People with a previous low DAO result - Repeat testing may provide information about whether the finding remains present.
People undertaking specialist nutritional or allergy assessment - DAO may be considered alongside a careful food and symptom history.
People specifically advised to obtain Diamine Oxidase Activity testing - The test is most useful where a clinician has identified a specific reason for measuring DAO.
How to Prepare
Do not make major restrictive dietary changes solely on the basis of one DAO result.
Where histamine intolerance is suspected, a structured clinical assessment and carefully supervised dietary approach are generally more informative than interpreting DAO in isolation.
Symptoms and Reasons to Consider the Diamine Oxidase Test
Symptoms attributed to reduced histamine tolerance are often episodic and food-related, but none are specific enough to diagnose the condition without wider assessment.
Facial flushing after certain foods or alcohol - Histamine can dilate blood vessels and may contribute to transient flushing.
Headaches or migraine-like symptoms after particular foods - Histamine is one of several possible dietary triggers.
Bloating or abdominal discomfort - Gastrointestinal symptoms can occur following food exposure but overlap extensively with IBS and other digestive conditions.
Loose stools or diarrhoea after histamine-rich foods - Histamine can influence gastrointestinal secretion and motility.
Nasal congestion or a runny nose after meals - Histamine can produce upper-airway symptoms in susceptible individuals.
Palpitations following certain foods or alcohol - Histamine can influence cardiovascular activity, although palpitations have many potential causes.
Itching or skin redness without a clear IgE allergy - Histamine-mediated skin symptoms can occur through several different mechanisms.
Symptoms associated with fermented, aged or cured foods - Foods such as aged cheese, processed meats and fermented products can contain relatively high histamine levels.
Symptoms after wine or other alcoholic drinks - Alcohol can contain histamine and may also influence histamine metabolism.
These symptoms are not specific to low DAO activity, and a low result should not automatically be interpreted as proof of histamine intolerance.
Severe wheezing, throat swelling, collapse or rapidly progressing symptoms after food exposure may represent anaphylaxis and require emergency medical care rather than investigation with a routine DAO test.
How to Book Your Diamine Oxidase Test
Booking your Diamine Oxidase test with London Blood Tests is straightforward.
Choose the Diamine Oxidase
Select the individual Diamine Oxidase Activity blood test.
Select your sample collection option
Choose an in-clinic blood draw or professional home or hotel phlebotomy depending on availability.
Attend your appointment
A trained healthcare professional collects the required venous blood sample.
Laboratory analysis
Your serum undergoes specialist measurement of Diamine Oxidase Activity.
Receive your results securely
Your authorised result is delivered securely and can be reviewed alongside your food, allergy and gastrointestinal history.
When Will I Receive My Results?
The current expected turnaround time for the Diamine Oxidase test is approximately 2 weeks after your sample reaches the laboratory.
DAO activity is a specialist biochemical assay rather than a routinely processed marker, so laboratory analysis takes longer than standard tests such as Ferritin or Magnesium.
The turnaround begins from laboratory receipt rather than necessarily from the time your blood is collected.
Once specialist analysis, quality-control procedures and laboratory authorisation are complete, your result is released securely. Occasional referral-laboratory processing or repeat analysis may extend reporting beyond the usual timeframe.
Understanding Your Results
A lower DAO activity result means the measured enzyme activity is below or towards the lower end of the laboratory's reporting range.
This may support the possibility of impaired histamine degradation when the clinical history is strongly compatible.
However, low DAO activity is not a validated standalone diagnosis of histamine intolerance.
Some people with low DAO activity do not experience clinically significant food-related symptoms, while people with symptoms attributed to histamine can occasionally have DAO results within the reference interval.
A result within the laboratory range therefore does not completely exclude a possible relationship between symptoms and dietary histamine.
Interpretation should consider symptoms, food exposure, gastrointestinal disease, medication and alternative explanations.
IgE-mediated food allergy, mast-cell activation and histamine intolerance are different biological processes and require different diagnostic approaches.
Why Book With London Blood Tests?
Private DAO testing in London - Access specialist Diamine Oxidase Activity measurement privately.
Targeted histamine-metabolism assessment - The test provides information about an enzyme involved in dietary histamine degradation.
Useful alongside a food and symptom history - Results can complement structured clinical assessment.
No deliberate histamine challenge required - Blood can be collected without intentionally provoking symptoms.
Specialist laboratory analysis - DAO requires dedicated biochemical testing.
Clinic and home collection options - Professional phlebotomy can be arranged according to availability.
Secure reporting - Receive your authorised result securely.
Clear pricing - The Diamine Oxidase test costs £99.
Private Diamine Oxidase Blood Test in London
London Blood Tests provides private Diamine Oxidase blood testing in London for people requiring specialist assessment of DAO activity.
The test costs £99 and measures one biomarker: Diamine Oxidase Activity.
Results are expected approximately 2 weeks after laboratory receipt.
DAO results should be interpreted cautiously because histamine intolerance cannot be diagnosed from one laboratory measurement alone.