What are the treatment options for thyroid diseases?

Treatment Options for Thyroid Diseases

The treatment of thyroid diseases should be tailored to the specific type of thyroid disorder, with total or near-total thyroidectomy being the primary treatment for differentiated thyroid cancer, levothyroxine for hypothyroidism, and antithyroid medications, radioactive iodine, or surgery for hyperthyroidism. 1, 2

Differentiated Thyroid Cancer (DTC)

Initial Treatment

• Total or near-total thyroidectomy is the standard initial treatment for DTC when the diagnosis is made before surgery and the nodule is ≥1 cm, or regardless of size if there is metastatic, multifocal, or familial DTC 1
• Less extensive surgical procedures may be acceptable for unifocal DTC diagnosed after surgery for benign thyroid disorders, provided the tumor is small, intrathyroidal, and of favorable histology 1
• Prophylactic central node dissection remains controversial but permits accurate staging that may guide subsequent treatment 1
• Compartment-oriented microdissection of lymph nodes should be performed when lymph node metastases are suspected or proven 1

Radioactive Iodine (RAI) Therapy

• RAI administration is not recommended for small (≤1 cm) intrathyroidal DTC with no evidence of locoregional metastases (low-risk cases) 1
• For other low-risk DTCs, if RAI is given, low activities (30 mCi, 1.1 GBq) following recombinant human TSH (rhTSH) administration are recommended 1
• RAI therapy may be considered in intermediate-risk patients (30-100 mCi, 1.1-3.7 GBq) 1
• High RAI activities (100 mCi, 3.7 GBq) are recommended for high-risk patients 1

Thyroid Hormone Therapy

• After total thyroidectomy, levothyroxine therapy is initiated with dual aims: to replace thyroid hormone and to suppress potential TSH stimulation of tumor cells 1
• TSH suppressive treatment benefits high-risk thyroid cancer patients by potentially decreasing progression of metastatic disease 1
• In patients with persistent or metastatic disease, an undetectable serum TSH (<0.1 mU/l) should be maintained 1
• In patients free of disease, LT4 therapy may be shifted from suppressive to replacement 1

Medullary Thyroid Cancer (MTC)

Initial Treatment

• Total thyroidectomy with bilateral prophylactic central lymph-node dissection is recommended for both sporadic and hereditary MTC 1
• Lateral neck dissection may be reserved for patients with positive preoperative imaging 1
• In the presence of distant metastatic disease, less aggressive neck surgery may be appropriate to preserve speech, swallowing, and parathyroid function 1

Follow-up

• After surgery, serum calcitonin (CT) and carcinoembryonic antigen (CEA) measurements are crucial for monitoring 1
• Undetectable basal serum CT level is a strong predictor of complete remission 1
• Patients with biochemical remission after initial treatment have only a 3% chance of recurrence during long-term follow-up 1

Anaplastic Thyroid Cancer (ATC)

Treatment Approach

• ATC is rarely amenable to complete resection; incomplete palliative resection does not affect prognosis and is not recommended 1
• Optimal outcomes require complete or near-complete resection followed by high-dose external beam radiotherapy (EBRT), with or without concomitant chemotherapy 1
• Post-operative radiotherapy must be delivered as soon as possible after surgery 1
• Multidisciplinary team discussion is strongly recommended 1
• ATC has a very poor prognosis with median survival of about 5 months 1

Hypothyroidism

Levothyroxine Therapy

• Levothyroxine sodium tablets are indicated for replacement therapy in primary (thyroidal), secondary (pituitary), and tertiary (hypothalamic) congenital or acquired hypothyroidism 2
• Administer once daily, preferably on an empty stomach, one-half to one hour before breakfast with a full glass of water 2
• Starting dose depends on age, body weight, cardiovascular status, and concomitant medications 2
• Peak therapeutic effect may not be attained for 4-6 weeks 2
• In adult patients with primary hypothyroidism, monitor serum TSH levels after 6-8 weeks following any dosage change 2
• For stable patients, evaluate clinical and biochemical response every 6-12 months 2

Special Populations

• For pregnant patients with pre-existing hypothyroidism, measure serum TSH and free-T4 as soon as pregnancy is confirmed and during each trimester 2
• In pregnant patients with primary hypothyroidism, maintain serum TSH in the trimester-specific reference range 2
• For pediatric patients, assess adequacy of replacement therapy by measuring both serum TSH and total or free-T4 2
• To minimize risk of hyperactivity in pediatric patients, start at one-fourth the recommended full replacement dosage and increase weekly 2

Hyperthyroidism

Treatment Options

• Three main treatment modalities: antithyroid medications, radioactive iodine (I-131), and surgery 1
• Antithyroid medications (thioamides such as methimazole) are often first-line therapy 1
• Radioactive iodine (I-131) is contraindicated in pregnant women 1
• Thyroidectomy should be reserved for patients who do not respond to thioamide therapy 1

Thyroid Storm

• This extreme hypermetabolic state carries high risk of maternal heart failure if occurring during pregnancy 1
• Standard treatment includes propylthiouracil or methimazole, potassium iodide or sodium iodide, dexamethasone, and supportive measures 1

Subclinical Thyroid Disease

Subclinical Hyperthyroidism

• Defined as suppressed serum TSH and normal serum thyroxine and triiodothyronine levels 3
• May adversely affect heart and bones; should be treated, especially in patients older than 60 years 3

Subclinical Hypothyroidism

• Defined as mildly elevated serum TSH and normal serum thyroxine levels 3
• Thyroxine therapy should be given if serum TSH level is higher than 10 mIU/L 3
• For TSH values between 5 and 10 mIU/L, therapy should be individualized based on TSH level, presence of antithyroid antibodies, and clinical factors 3

Follow-up Considerations

For Differentiated Thyroid Cancer

• The aim of follow-up is early discovery and treatment of persistent or recurrent disease 1
• Two to three months after initial treatment, thyroid function tests should be obtained to check adequacy of LT4 suppressive therapy 1
• At 6-12 months, follow-up should include physical examination, neck ultrasound, and serum thyroglobulin measurement 1
• Long-term follow-up consists of physical examination, basal serum thyroglobulin measurement on LT4 therapy, and neck ultrasound once a year 1

For Medullary Thyroid Cancer

• Serum markers CT and CEA and their doubling times are crucial in post-surgical follow-up 1
• After surgery, serum CT level normalizes in 60-90% of cases with no lymph-node involvement but only in 20% of those with lymph-node metastases 1

Important Considerations and Caveats

• Thyroid hormones, including levothyroxine sodium, should not be used for treatment of obesity or weight loss 2
• Overtreatment with thyroid hormone can produce serious or even life-threatening manifestations of toxicity 2
• Persistent clinical and laboratory evidence of hypothyroidism despite an apparent adequate replacement dose may indicate inadequate absorption, poor compliance, or drug interactions 2
• Thyroid disease can significantly impact cardiovascular health, with both hypo- and hyperthyroidism associated with increased cardiovascular risk 4
• Pregnant women with thyroid disorders require special attention and monitoring throughout pregnancy 1, 2