Autoimmune Thyroiditis
When the immune system attacks the thyroid gland
Quick Facts
- Type: Autoimmune endocrine disorder
- Main effect: Often leads to an underactive thyroid
- Most common form: Hashimoto thyroiditis
- Who is affected: More common in women and with age
Overview
Autoimmune thyroiditis is a condition in which the body's immune system mistakenly attacks the thyroid, a butterfly-shaped gland in the neck that produces hormones controlling metabolism. The most common form is Hashimoto thyroiditis, also called chronic lymphocytic thyroiditis.
Over time, the immune attack causes inflammation and damage to the thyroid, which often leads to an underactive thyroid (hypothyroidism), where too little thyroid hormone is made. It is the most common cause of hypothyroidism in many parts of the world. The condition develops slowly and may go unnoticed for years. It is far more common in women and becomes more frequent with age. While there is no cure for the underlying autoimmune process, the resulting hormone deficiency is easily and effectively treated.
Symptoms
Many people have no symptoms early on. As thyroid hormone levels fall, symptoms of an underactive thyroid gradually appear.
- Fatigue and sluggishness
- Feeling cold and sensitivity to cold
- Unexplained weight gain
- Dry skin and hair, and hair thinning
- Constipation
- Puffiness of the face and a possible enlarged thyroid (goiter)
- Depressed mood, poor concentration, and memory problems
- Heavier or irregular menstrual periods
- Muscle aches, stiffness, and slowed reflexes
Occasionally, early in the disease, brief periods of an overactive thyroid can occur as stored hormone is released, causing temporary symptoms such as palpitations or anxiety.
Causes
Autoimmune thyroiditis occurs when the immune system produces antibodies that target the thyroid, leading to chronic inflammation and gradual destruction of thyroid tissue. The exact reason the immune system does this is not fully understood, but a combination of genetic and environmental factors is involved.
A family history of thyroid or other autoimmune disease increases risk, and the condition often coexists with other autoimmune disorders such as type 1 diabetes, vitiligo, and celiac disease. Excess iodine, certain medications, and possibly viral infections may contribute in some people.
Risk Factors
- Being female
- Middle age, though it can occur at any age
- A family history of thyroid or autoimmune disease
- Having another autoimmune condition, such as type 1 diabetes or celiac disease
- Pregnancy and the postpartum period
- Excess iodine intake or certain medications
Diagnosis
Diagnosis is based on blood tests and, when needed, imaging.
- Thyroid function tests: Measuring thyroid-stimulating hormone (TSH) and thyroid hormone (T4) levels; a high TSH with low T4 indicates an underactive thyroid.
- Thyroid antibody tests: Detecting antibodies (such as anti-TPO antibodies) that point to autoimmune thyroiditis.
- Ultrasound: Used if the gland is enlarged or has nodules, to look at its size and texture.
Treatment
Treatment focuses on replacing the thyroid hormone that the damaged gland can no longer make in sufficient amounts.
- Thyroid hormone replacement: A daily tablet of levothyroxine, a synthetic form of thyroid hormone, restores normal levels and relieves symptoms. The dose is adjusted using blood tests.
- Regular monitoring: Periodic TSH testing ensures the dose remains correct, as needs can change over time.
- Monitoring without treatment: If thyroid function is still normal but antibodies are present, doctors may simply monitor levels over time and start treatment if the thyroid becomes underactive.
The underlying autoimmune process cannot be cured, but with the right dose of hormone replacement, most people feel well and live normally.
Living With the Condition
- Take thyroid medication consistently, ideally at the same time each day
- Keep up with regular blood tests to keep the dose correct
- Tell your doctor about pregnancy plans, as thyroid needs change
- Mention all medicines and supplements, since some affect absorption of thyroid hormone
- Be aware of overlapping autoimmune conditions and report new symptoms
- Eat a balanced diet and avoid taking high-dose iodine supplements unless advised
When to See a Doctor
See a doctor if you have persistent tiredness, unexplained weight gain, cold intolerance, dry skin, or other symptoms suggesting an underactive thyroid, especially with a family history of thyroid disease. A neck swelling (goiter) or difficulty swallowing also warrants evaluation. If you are already being treated, contact your doctor if symptoms return or new ones develop, as your dose may need adjusting. Severe untreated hypothyroidism is rare but serious, so do not ignore worsening fatigue, confusion, or marked cold intolerance.
Frequently Asked Questions
What is autoimmune thyroiditis?
It is a condition in which the immune system attacks the thyroid gland, causing inflammation and gradual damage. The most common form is Hashimoto thyroiditis, and over time it often leads to an underactive thyroid that needs hormone treatment.
Is autoimmune thyroiditis the same as Hashimoto disease?
Hashimoto thyroiditis is the most common type of autoimmune thyroiditis, so the terms are often used interchangeably. Both describe an immune attack on the thyroid that typically leads to hypothyroidism.
How is autoimmune thyroiditis treated?
If it has caused an underactive thyroid, treatment is a daily dose of levothyroxine, a synthetic thyroid hormone, with periodic blood tests to keep the dose right. The autoimmune process itself cannot be cured, but replacing the hormone controls symptoms effectively.
Can autoimmune thyroiditis be cured?
There is no cure for the underlying autoimmune condition, but the resulting hormone deficiency is easily managed with daily thyroid hormone replacement. Most people feel well once their levels are restored to normal.
Does autoimmune thyroiditis affect pregnancy?
It can, because thyroid hormone is important for pregnancy and a developing baby. Women with the condition often need closer monitoring and dose adjustments during pregnancy, so it is important to tell your doctor if you are pregnant or planning to be.
References
- National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). Hashimoto's Disease.
- American Thyroid Association. Hashimoto's Thyroiditis.
- Mayo Clinic. Hashimoto's disease — Symptoms and causes.
- MedlinePlus, U.S. National Library of Medicine. Hashimoto disease.