Completion Thyroidectomy
A completion thyroidectomy is a second operation that removes the rest of the thyroid after an earlier lobectomy. It is most often performed when cancer is found in the first specimen and the remaining tissue also needs to be removed.
The decision is individualised — not everyone who has a lobectomy for cancer needs completion surgery.
Last medically reviewed: 15 November 2025
Key points
- Completion thyroidectomy removes the remaining thyroid lobe.
- It is usually done when cancer is found after a lobectomy.
- The timing and need depend on the cancer type, size and risk.
- Lifelong levothyroxine is needed afterwards.
Why it is needed
If a lobectomy specimen shows thyroid cancer, the remaining lobe may also contain disease or be needed for radioactive iodine treatment. Completion surgery removes that tissue and allows accurate staging.
For small, low-risk cancers confined to one lobe, surveillance may be sufficient instead — the decision is made with your team.
Timing
Completion surgery is usually performed a few weeks to a few months after the first operation, allowing the initial site to heal. The timing is planned with your surgeon and, where relevant, the oncology team.
The operation and recovery
The procedure resembles the original surgery, removing the remaining lobe through the same neck incision. Risks include voice change and low calcium, which are discussed with your surgeon.
Recovery is similar to the first operation, though scar tissue can make the surgery slightly more complex.
After surgery
Levothyroxine is started because the body can no longer make thyroid hormone. Thyroid function and, for cancer, tumour markers and imaging are monitored through follow-up.
When to seek urgent medical help
- Breathing difficulty or rapidly increasing neck swelling after surgery.
- Tingling around the mouth or muscle cramps.
- A persistent or worsening voice change.
This guidance does not replace emergency services. If you are seriously unwell, seek urgent medical care immediately.
Frequently asked questions
Will I always need completion surgery after a lobectomy for cancer?
No — it depends on the cancer type, size, margins and risk. Some low-risk cancers can be managed with surveillance.
Is the second surgery riskier?
It carries similar risks to the first, though scar tissue can make it slightly more complex. Your surgeon will discuss this.
Will I need radioactive iodine afterwards?
Possibly — it depends on the cancer stage and risk. Completion surgery makes radioactive iodine more effective when it is needed.
Will I need medication for life?
Yes — after completion thyroidectomy, levothyroxine replacement is lifelong.
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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