Management of Levothyroxine Before Surgery

Rationale for Continuing Levothyroxine

• Levothyroxine is a thyroid hormone replacement medication that should be maintained at consistent levels to avoid fluctuations in thyroid hormone status 1
• Postoperative levothyroxine is indicated for all thyroidectomy patients, with TSH kept in the normal range through appropriate dosing 1
• Unlike medications that may increase bleeding risk or interfere with anesthesia, levothyroxine does not need to be held before surgery 2
• The National Comprehensive Cancer Network recommends that levothyroxine should be continued and administered on the morning of surgery 1, 3

Special Considerations

Thyroid Cancer Patients

• For patients with differentiated thyroid cancer, TSH suppression therapy is an important part of treatment, as recommended by the European Society for Medical Oncology 4
• In high-risk thyroid cancer patients, maintaining TSH suppression may decrease progression of metastatic disease, according to the American Thyroid Association 4
• Interrupting levothyroxine therapy could lead to rising TSH levels, which is undesirable in thyroid cancer management, as stated by the American Cancer Society 4

Medullary Thyroid Carcinoma Patients

• For patients with medullary thyroid carcinoma (MTC), TSH suppression is not appropriate since C cells lack TSH receptors, as noted by the National Comprehensive Cancer Network 1
• However, these patients still require levothyroxine replacement to maintain normal thyroid function, as recommended by the American Thyroid Association 1
• TSH should be kept in the normal range through appropriate levothyroxine dosing, according to the Endocrine Society 1

Management of Thyronorm (Levothyroxine) on the Day of Surgery

Special Patient Populations

• TSH suppression (serum level <0.1 μIU/mL) is recommended for all thyroid cancer patients with persistent structural disease in the absence of specific contraindications, according to the American Society of Clinical Oncology 5

Peri‑operative Levothyroxine Management in Thyroid Cancer Patients

Guideline Recommendations for Differentiated Thyroid Cancer

The European Society for Medical Oncology (ESMO) guideline advises that levothyroxine should be continued on the morning of low‑risk surgery to maintain appropriate thyroid‑stimulating hormone (TSH) targets peri‑operatively【6】.
Evidence level: Guideline recommendation (expert consensus).

Target TSH ranges according to disease risk (as defined by ESMO):
Evidence level: Guideline recommendation (expert consensus).

Management in Medullary Thyroid Carcinoma (MTC)

According to the Annals of Oncology 2012 review, MTC patients do not require TSH suppression because C‑cells lack TSH receptors, but they still need levothyroxine replacement to sustain normal thyroid function【7】.
Evidence level: Expert review (moderate).

TSH should be maintained in the normal reference range (approximately 0.5–4.5 mIU/L) through appropriate levothyroxine dosing in MTC patients【7】.
Evidence level: Expert review (moderate).

Avoiding Mismanagement

Evidence level: Guideline recommendation (expert consensus).

Evidence level: Review article (low‑to‑moderate).