High TSH means your pituitary gland is working harder to stimulate an underactive thyroid. It is the most common indicator of hypothyroidism — a condition where the thyroid does not produce enough hormones.
Common Causes of High TSH
- Hashimoto's thyroiditis: An autoimmune attack on the thyroid gland.
- Hypothyroidism: The thyroid simply underproduces T3 and T4.
- Iodine deficiency: Rare in developed countries but possible.
- Post-thyroid surgery or radiation: Reduced thyroid tissue lowers hormone output.
- Certain medications: Lithium, amiodarone, and some cancer drugs.
High TSH with Normal T4
This is called subclinical hypothyroidism. You may feel fine, or you may have mild symptoms like fatigue or weight gain. Doctors often treat it if TSH is above 10 mIU/L or if symptoms are present.
Dangers of Untreated High TSH
Over time, untreated high TSH can contribute to high cholesterol, heart disease, depression, infertility, and nerve damage. Early detection through a simple TSH blood test allows for prompt treatment.
How to Lower TSH Levels
The standard treatment is levothyroxine, a synthetic thyroid hormone that replaces what your body lacks. Regular TSH monitoring ensures the dose stays optimal. Learn more about symptoms on our high TSH symptoms page.
Related Tests
If hypothyroidism is suspected, your doctor may also recommend a TPO antibody test to check for Hashimoto's, or a comprehensive health screening to evaluate overall wellness.
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