Tissue Transglutaminase IgA Antibody (tTG IgA) Test

A tissue transglutaminase antibody IgA test may be ordered in the following conditions:

• To diagnose coeliac disease
• To monitor coeliac disease
• To determine if a gluten-free diet is helping in relieving the symptoms of coeliac disease. 

Symptoms of coeliac vary in adults and children: 

Common symptoms in children are:

• Vomiting
• Bloating
• Pale, foul-smelling or fatty stools that float
• Constipation
• Gas
• Chronic diarrhoea
• Nausea
• Stomach pain

Children with coeliac may also show the following symptoms as they are unable to absorb nutrients from the food properly:

• Damage to tooth enamel 
• Slowed growth and short stature
• Delayed puberty
• Mood swings 
• Weight loss

Adults may show some of the following symptoms:

• Weak and brittle bones
• Anaemia
• Bone pain or joint pain
• Depression or anxiety
• A red, smooth, shiny tongue
• Dermatitis herpetiformis (an itchy, blistering skin rash commonly seen at the elbows, knees, buttocks, back or scalp)
• Headaches
• Infertility or repeated miscarriage
• Seizures
• Mouth problems like canker sores or dry mouth
• Missed menstrual periods
• Tingling numbness in the hands and feet
• Tiredness

Some of the symptoms of the coeliac disease specifically related to the digestive system in adults are as follows:

• Tiredness for longer periods of time
• Abdominal pain and bloating
• Intestinal blockages
• Sores or ulcers on the lining of the intestine or stomach (Read more: Peptic ulcers symptoms)

The following are the risk factors of coeliac disease:

• A family history of coeliac disease
• Conditions such as:
  • Down syndrome
  • Turner syndrome
  • Type 1 diabetes

If this test is being done to diagnose coeliac disease, you’ll be asked to continue having gluten-rich foods for some weeks until the test. However, no preparations are needed if the test is performed to keep a check on coeliac disease.

Tell your doctor about all the drugs, supplements and vitamins that you are using.

A blood sample is needed for this test. A laboratory technician will withdraw a small amount of blood from a vein in your arm using a sterile needle. 

• They will first tie a tourniquet (a tight band) around your arm and use an antisceptic to wipe the skin above a vein in the bend of your elbow.
• They will then insert the needle and draw the required amount of blood.
• After drawing the sample, the technician will remove the tourniquet and needle, and place a cotton swab on the site.
• They will then transfer the sample into a labelled container and send it to the lab for testing.

Blood tests have the following risks:

• Feeling light-headed
• Infection
• Bleeding
• Bruising

When the technician inserts the needle, you may feel mild pain, and later there may be some soreness at the site.

Normal results:

The normal levels of tissue transglutaminase antibody in the blood are 3 U/mL or less and are interpreted as negative. The results may vary based on:

• Gender
• Age
• Medical history
• Method of performing the test

Abnormal results:

The test results will be considered positive at antibody levels of 4 U/mL and above. A positive result is associated with conditions such as coeliac disease and dermatitis herpetiformis. Additional tests may need to be ordered if you have a positive result.

Disclaimer: All results must be clinically correlated with the patient’s complaints to make a complete and accurate diagnosis. The above information is provided from a purely educational point of view and is in no way a substitute for medical advice by a qualified doctor.