Thyroid peroxidase

The thyroid is a small, butterfly-shaped gland on the neck, in front of the tracheae. It primarily produces thyroid hormones, i.e. thyroxine (T4) and triiodothyronine (T3), to regulate the speed of energy consumption. Microsomal thyroid peroxidase (TPO) helps to transform T4 to T3 and vice versa, from T3 to T4, according to the needs of the body. When a person’s own immune system mistakes the thyroid gland or its proteins as foreign, you develop thyroid autoimmune disease, and your blood has auto-antibodies against thyroid peroxidase (TPOAb). The antibodies affect TPO's role in balancing thyroid hormones, and the body develops conditions where the level of thyroid hormones is too high or too low, leading to thyroiditis (inflammation of the thyroid gland), tissue damages and disturbance of thyroid function. TPO antibodies are more common in women than in men. If a pregnant mother has TPO antibodies, it increases the risk of giving birth to a child with hypothyroidism (underactive thyroid) or hyperthyroidism (overactive thyroid).

When should TPOAb be measured?

Hypothyroidism (underactive thyroid) can cause symptoms

• Weight gain
• Fatigue
• Feeling of pressure on the neck (enlarged thyroid gland)
• Dry skin
• Hair loss
• Intolerance to cold
• Constipation

Hyperthyroidism (overactive thyroid) can cause symptoms

• Sweating
• Fast pulse
• Anxiety
• Tremor
• Fatigue
• Sleep problems
• Sudden weight loss
• Bulging eyes

What does a TPOAb test measure?

The test shows if there are thyroid antibodies in the blood in case of detected or suspected disorder of thyroid function. Antibody testing is requested primarily to help to diagnose autoimmune thyroid disease and to distinguish it from other inflammations of the thyroid gland and other forms of thyroid diseases.