What is thyroid peroxidase?
Thyroid peroxidase (TPO) is an enzyme that helps convert thyroxine (T4) to triiodothyronine (T3) — these hormones help control your metabolism.
A TPO antibody test checks for the presence of antibodies against TPO. High levels of these antibodies can indicate that you have an autoimmune disorder.
TPOAb is sometimes referred to as anti-thyroid peroxidase antibodies (TPEX).
What is their function?
TPOAb are not normally found in your body. If you have an autoimmune thyroid disorder, these antibodies are produced and attack your thyroid.
Raised TPOAb levels can indicate Hashimoto’s disease (autoimmune thyroiditis) — which causes an underactive thyroid. Up to 95% of people with Hashimoto’s will have TPO antibodies in their blood which makes it a good marker for diagnosing this disease. It's not as common, but they might also indicate Grave’s disease — which causes an overactive thyroid.
What can cause it to change?
Autoimmune thyroid disorders are thought to be caused by a combination of genetic and environmental factors. Risk factors include:
- a family history of autoimmune diseases
- being female
- iodine intake
- certain medications
What are the most common symptoms?
If your TPOAb levels are rasied, you might have an autoimmune thyroid disorder. This can cause an under or overactive thyroid.
If your thyroid is underactive, like with Hashimoto's disease, common symptoms include:
- weight gain
- dry skin
- brittle hair
- sensitivity to cold
- memory problems
- muscle aches
- hoarse voice
If your thyroid is overactive, like with Grave's disease, common symptoms include:
- weight loss
- increased appetite
- excessive sweating
- sensitivity to heat
- irritability and anxiety
- heart palpitations
- difficulty sleeping
In women, high or low thyroid hormones might affect your period — for example, it might cause heavy or irregular periods.
What can I do to change my levels?
There are a number of nutrients that are important for your thyroid function:
- Iodine — needed to make thyroid hormones
- Zinc — needed to make thyroid hormones
- Selenium — needed to thyroid hormones
- Iron — plays an important role in thyroid hormone metabolism
- Vitamin D — plays an important role in your immune function and low levels are linked to autoimmune thyroid disorders
If your levels indicate you have a thyroid disorder, it’s important to work with your doctor to come up with a treatment plan.