TSH Suppression Therapy
After treatment for differentiated thyroid cancer, levothyroxine is often given at a dose high enough to keep TSH low or suppressed. Because TSH stimulates thyroid cells — including cancer cells — lowering it reduces the drive for any residual disease to grow.
This is a deliberate balancing act: enough hormone to suppress TSH, but not so much that it causes over-replacement problems.
Last medically reviewed: 15 November 2025
Why it works
TSH is the main growth signal for thyroid cells. Differentiated thyroid cancer cells usually retain TSH receptors, so suppressing TSH reduces their stimulation.
The degree of suppression is individualised by risk: higher-risk cancers are suppressed more aggressively, while low-risk cases may only need TSH kept in the lower part of normal.
The trade-offs
Over-replacement with thyroid hormone can cause palpitations, anxiety, insomnia and weight loss, and over the long term increases the risk of atrial fibrillation and bone loss, particularly in older people and postmenopausal women.
For these reasons, suppression is used for as long as the benefit outweighs the risk, and is often relaxed over time.
Monitoring
TSH is checked regularly to keep it in the target range. As the risk of recurrence falls, the target is usually relaxed towards normal.
Bone health and heart rhythm may be monitored, especially in those who need prolonged suppression.
Frequently asked questions
What is TSH suppression?
It means keeping TSH low with a slightly higher levothyroxine dose to reduce stimulation of any remaining thyroid cancer cells.
Will I be suppressed forever?
Not necessarily — suppression is usually relaxed over time as the risk of recurrence falls. The duration is individualised.
What are the risks?
Prolonged over-replacement can affect heart rhythm and bone density. Monitoring helps balance the benefit against these risks.
References & further reading
This page is based on established medical knowledge and guidelines from authoritative sources. Always consult a qualified clinician for personal medical advice.
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