Endocrine Tumors

Thyroid and Parathyroid Glands

Thyroid Cancer

Thyroid Nodule

Diagnosis

Physical exam
Asked to swallow -- a nodule in thyroid gland will usually move up and down during swallowing.
Signs and symptoms of hyperthyroidism, such as tremor, overly active reflexes, and a rapid or irregular heartbeat; and signs and symptoms of hypothyroidism, such as a slow heartbeat, dry skin and facial swelling.
Thyroid function tests
T4, T3, TSH
Ultrasonography
This imaging technique uses high-frequency sound waves to produce images.
It provides the best information about the shape and structure of nodules. It may be used to distinguish cysts from solid nodules or to determine if multiple nodules are present. It may also be used as a guide in performing a fine-needle aspiration biopsy.
Fine-needle aspiration (FNA) biopsy
Nodules are often biopsied to make sure no cancer is present. FNA biopsy helps to distinguish between benign and malignant thyroid nodules.
Thyroid scan
An isotope of radioactive iodine is injected into a vein in the arm, while a special camera produces an image of thyroid on a computer screen.
Nodules that produce excess thyroid hormone — called hot nodules — show up on the scan because they take up more of the isotope than normal thyroid tissue does.
Cold nodules are nonfunctioning and appear as defects or holes in the scan. Hot nodules are almost always noncancerous, but a few cold nodules are cancerous. The disadvantage of a thyroid scan is that it can't distinguish between benign and malignant cold nodules.

Treatment

Treatment depends on the type of thyroid nodule you have.

Treating benign nodules
If a thyroid nodule isn't cancerous, there are several treatment options:
Watchful waiting
If a biopsy shows that you have a benign thyroid nodule, suggest simply watching your condition. This usually means having a physical exam and thyroid function tests at regular intervals. You're also likely to have another biopsy if the nodule grows larger. If a benign thyroid nodule remains unchanged, you may never need treatment.
Thyroid hormone suppression therapy This involves treating a benign nodule with levothyroxine (Levoxyl, Synthroid, others). The idea is that supplying additional thyroid hormone will signal the pituitary to produce less TSH, the hormone that stimulates the growth of thyroid tissue.
Although this sounds good in theory, levothyroxine therapy is a matter of some debate. There's no clear evidence that the treatment consistently shrinks nodules or even that shrinking small, benign nodules is necessary.
Surgery Occasionally, a nodule that's clearly benign may require surgery, especially if it's so large that it makes it hard to breathe or swallow. Surgery is also considered for people with large multinodular goiters, particularly when the goiters constrict airways, the esophagus or blood vessels. Nodules diagnosed as indeterminate or suspicious by a biopsy also need surgical removal, so they can be examined for signs of cancer.

Treating nodules that cause hyperthyroidism
If a thyroid nodule is producing thyroid hormones, may recommend treating for hyperthyroidism. This may include:
Radioactive iodine
Doctors often use radioactive iodine to treat hyperfunctioning adenomas or multinodular goiters.
Taken as a capsule or in liquid form, radioactive iodine is absorbed by thyroid gland. This causes the nodules to shrink and signs and symptoms of hyperthyroidism to subside, usually within two to three months.
Anti-thyroid medications In some cases, your doctor may recommend an anti-thyroid medication such as methimazole (Tapazole) to reduce symptoms of hyperthyroidism. Treatment is generally long term and can have serious side effects on your liver, so it's important to discuss the treatment's risks and benefits with your doctor. Surgery. If treatment with radioactive iodine or anti-thyroid medications isn't an option, you may be a candidate for surgery to remove the overactive thyroid nodule. Surgery also carries certain risks that should be thoroughly discussed with your doctor.

Treating cancerous nodules
Treatment for a nodule that's cancerous usually involves surgery.
Surgery
The usual treatment for malignant nodules is surgical removal, often along with the majority of thyroid tissue — a procedure called near-total thyroidectomy. Risks of thyroid surgery include damage to the nerve that controls your vocal cords (laryngeal nerve) and damage to your parathyroid glands — four tiny glands located on the back of your thyroid gland that help control the level of calcium in your blood.
After a thyroidectomy, you'll need lifelong treatment with levothyroxine.
Alcohol ablation
Another option for management of certain small cancerous nodules is alcohol ablation. This technique involves injecting a small amount of alcohol in the cancerous thyroid nodule.
This treatment is helpful for treating cancer that occurs in areas that aren't easily accessible during surgery. Multiple treatment sessions are often required.

Solitary Thyroid Nodule Treatment & Management

Medical Care
After initial diagnosis and investigation of the thyroid nodule, medical and/or surgical therapy is decided.

A presumed benign nodule, especially in an adolescent, may simply be observed. Close observation and follow-up care is essential. The patient should be closely monitored for change of size and the development of symptoms.

Treatment of autoimmune thyroiditis involves hormone replacement to maintain a euthyroid state.

Treat infection appropriately. Abscesses should be drained and antibiotics should be administered. In patients with immunocompromise, be aware of the remote possibility of local spread to mediastinal structures.

A warm nodule without physical signs of malignancy is usually benign and may be observed with close follow-up for growth or change in the nodule.

A hot toxic nodule may require medical therapy before surgical removal to allow for operative stability. The patient should receive suppressive doses of antithyroid medications. Once physiologic stability is obtained, the surgeon can proceed with removal of the gland or lobe.

In the past, preoperative thyroid suppression was used to exclude benign disease. This no longer is recommended for several reasons (eg, the incidence of cancer in childhood thyroid nodules is high, and well-differentiated cancers may respond, delaying definitive diagnosis and treatment).

Routine preoperative and postoperative care includes the maintenance of nutrition and hydration as well as the observation for signs of complications.

The pediatrician or other primary care provider should closely cooperate with the surgeon to monitor for nerve injury or hypocalcemia. Calcium supplementation may be necessary in the individual with parathyroid compromise, whether temporarily or permanently. Closely monitor laboratory findings to determine the initial and ongoing requirements.

Recurrent laryngeal nerve injuries may cause dysphagia, which can endanger nutrition. In such an individual, involve speech pathology early to optimize recovery.

After thyroidectomy, thyroid hormone replacement is necessary. This therapy is continued for the child's lifetime. Thyroid hormone levels should be monitored periodically so that adequate therapy is maintained during growth and changing needs. If malignancy is diagnosed, radioablation therapy may be used for any residual disease.

Long-term follow-up care remains vital in such individuals to screen for disease progression or late recurrence.

Surgical Care
The presence of a thyroid nodule in children presents somewhat of a dilemma, given the less-than-ideal reliability of diagnostic tests. However, the increased incidence of malignancy in pediatric nodules has led to a somewhat more aggressive approach than that used in adults.

Indications for surgical excision
Indications for surgery include physical examination findings consistent with malignancy, persistence of a nodule, progressive increase in size, or the presence of significant risk factors, including family history or history of irradiation exposure. All toxic nodules in children should be removed. If the presence of malignancy is still in question after diagnostic tests and procedures have been completed, perform surgical excision. Some authorities recommend the removal of all nonsuppressible thyroid nodules found in children younger than 13 years.

In the presence of a small asymptomatic nodule, the surgeon may elect to perform a simple lobectomy with close follow-up observation. Complications with this surgery are generally low. In such an individual, full thyroid suppression also is recommended as lifetime postoperative therapy. Many adenomas contain mutations, causing them to be hyperresponsive to thyroid-stimulating hormone (TSH). The presence of such an adenoma may signify the presence of other cells bearing the same mutations.

Total thyroidectomy
With the presence of any metastases on diagnosis, including lymph node involvement, total thyroidectomy is the recommended treatment. [3] This procedure has decreased the rates of local and metastatic recurrence.

Postoperative radioablation is also more effective in this case because tissue to absorb the radioiodine is reduced.

Because the rate of pulmonary metastasis is high, postoperative radioiodine scintigraphy is performed 6 weeks after surgery to exclude the presence of pulmonary tumors. Scintigraphy is only reliable after total or subtotal thyroidectomy because any remaining tissue may hide the presence of metastases.

Total thyroidectomy should be performed in individuals with medullary thyroid cancer, preferably before evidence of disease is obvious. This malignancy is aggressive and metastasizes early.

Prophylactic therapy, with removal of the gland in children with a family history and genetic markers, provides the best outcomes with this malignancy.

If Graves disease is diagnosed, thyroidectomy (near-total to total) may be performed. Thyroid hormone replacement therapy may not be needed in this case if some tissue remains.

Surgical technique
Consultations
Diet
No specific dietary recommendations for individuals with thyroid nodules are indicated. Supplementary dietary iodine may be useful, especially in persons with iodine deficiency or iodine 131 (131 I) exposure.

Guidelines Summary
The American Thyroid Association (ATA) issued management guidelines for children with thyroid nodules and differentiated thyroid cancer. The guidelines included some of the following recommendations:
• For children at high risk for thyroid neoplasia, an annual physical examination is recommended and if the examination finds palpable nodules, thyroid asymmetry, and/or abnormal cervical lymphadenopathy, additional imaging is warranted.
• Instead of size alone, ultrasound characteristics and clinical context should be used to identify nodules that merit fine-needle aspiration which should be implemented using ultrasound guidance.
• Lobectomy may be done in patients with compressive symptoms and cosmetic concerns or if the patient or parent prefers. Consider lobectomy in all benign appearing solid thyroid nodules >4 cm, the lesions that have grown significantly, or if malignancy is a concern.
• The indications for 131I treatment are unresectable iodine-avid persistent locoregional or nodal disease and also for identified or assumed iodine-avid distant metastases.

Medication Summary
Possible medical therapy includes antithyroid medications, thyroid hormone replacement, and radioiodine ablation. Antithyroid therapy is used to physiologically stabilize the patient before surgical excision of a toxic nodule. Thyroid hormones are necessary postoperatively after thyroidectomy for replacement and suppression of thyroid-stimulating hormone (TSH). Radioiodine ablation may be employed to treat the presence of residual disease and sometimes for suppression of a toxic nodule. Its use requires the cooperation of an experienced specialist. In addition, calcium supplementation may be required in the case of parathyroid complications, whether temporarily or permanently.

Antithyroid agents
Class Summary ---These agents are used when treating hot nodules before surgery.
Methimazole (Tapazole)
Inhibits thyroid hormone by blocking oxidation of iodine in thyroid gland. However, it does not inhibit peripheral conversion of thyroid hormone. Gradually taper to minimum dose required to clinically maintain euthyroidism. Caution during pregnancy because it can cause fetal hypothyroidism and has been associated with fetal aplasia cutis.
Propylthiouracil (PTU)
Derivative of thiourea that inhibits organification of iodine by thyroid gland. Blocks oxidation of iodine in thyroid gland, thereby inhibiting thyroid hormone synthesis; inhibits conversion of T4 to T3 (an advantage over other agents). DOC in pregnancy-associated thyrotoxicosis but should be used in lowest effective dose because of risk of hypothyroidism to fetus.

Beta-adrenergic receptor blocking agents
Class Summary - These agents are used to control symptoms from hyperthyroidism. Inhibit chronotropic, inotropic, and vasodilatory responses to beta-adrenergic stimulation.
Propranolol (Inderal)
DOC in treating cardiac arrhythmias resulting from hyperthyroidism. Controls cardiac and psychomotor manifestations within minutes.

Further Outpatient Care
After surgery for a diagnosed thyroid malignancy, outpatient follow-up care is vital to optimize patient survival.

Radioiodine scintiscan may be used 6 weeks postsurgery to monitor for metastases. Uptake in the lungs, lateral neck, or around the recurrent laryngeal nerve indicates metastasis or residual disease. If these are discovered, therapeutic dosing of131 I is indicated to ablate remaining tumor cells. Thyroxine in full replacement doses to suppress thyroid-stimulating hormone (TSH) stimulation of malignant cells is necessary, even if some thyroid tissue remains.

Pediatric patients require periodic monitoring of thyroid hormone levels as the child grows to ensure adequate dosing. Annual radioiodine scan is recommended to monitor for long-term recurrence of disease.

Thyroglobulin levels may also be used to monitor for recurrence of disease, but only if a total thyroidectomy has been performed. Levels vary based on replacement therapy. Levels more than 1 ng/mL in patients on replacement therapy and 10 ng/mL in patients off thyroxine indicate recurrence of disease.

In patients with medullary thyroid cancer, calcitonin levels may be used to monitor for recurrence. Late mortality caused by unmonitored recurrence of disease is tragic. Therefore, primary care physicians should be diligent in maintaining long-term follow-up care.

Thyroid Cancer Treatment Protocols

These include a general treatment approach, as well as treatment recommendations for the three categories of thyroid cancer: differentiated (Hürthle cell, papillary, and follicular), anaplastic (undifferentiated), and medullary thyroid cancer.

General treatment recommendations for thyroid cancer

The treatment of choice for patients diagnosed with thyroid cancer is surgery, when possible. Usually, surgery is followed by treatment with radioiodine and thyroxine therapy. Generally, radiation therapy and chemotherapy do not have a prominent role in the treatment of thyroid cancer.

Radioactive iodine ablation
Postoperative whole-body scintigraphy scan may identify previously unrecognized disease and influence staging. If residual disease is found, adjuvant therapy with radioactive iodine (RAI) may be considered. Ablation of residual normal thyroid tissue facilitates early detection of recurrence based on serum thyroglobulin measurement and/or RAI whole-body scan.

RAI ablation is indicated for patients with any of the following:
• Large (>4 cm) tumors
• Known distant metastasis
• Gross extrathyroid extension

RAI ablation may be considered for tumors with the following characteristics:
• Moderate-size (1-4 cm) and node positive
• Grossly multifocal
• Aggressive, based on histology
• High risk, based on patient factors (age >45 y, history of head and neck radiation, family history of thyroid cancer)

RAI ablation is not recommended for the following:
• Small (<1 cm), solitary tumors
• Multifocal tumors when all foci are < 1 cm

Early data suggest that RAI is equally effective when used with thyroid hormone withdrawal or with recombinant human thyroid-stimulating hormone (rh-TSH) stimulation.

Thyroid-stimulating hormone (TSH) suppression therapy (levothyroxine)
TSH suppression to < 0.1 mU/L is indicated in intermediate and high-risk disease. TSH maintenance at or slightly below the lower-normal limit (0.3-2 mU/L) may be considered for low-risk disease

Therapy for unresectable gross residual or recurrent disease or metastases
Therapeutic options are as follows:
• Unresectable gross residual/recurrent disease/metastases may be treated with external beam radiation therapy (EBRT)
• Consider systemic treatment in the context of a clinical trial for persistent metastatic disease despite radioiodine, TSH suppression, and radiotherapy
• Consider tyrosine kinase inhibitors (TKIs) such as sorafenib 400 mg PO BID or sunitinib 50 mg PO daily for 4wk of a 6-wk cycle for patients who cannot participate in a clinical trial, as well as for those who are not likely to tolerate systemic therapy; since these drugs are usually tumorostatic rather than tumoricidal, they are considered second-line therapy compared with systemic treatments in clinical trials
• Pazopanib 800 mg PO daily may be considered for progressive or symptomatic metastatic differentiated (Hürthle cell, papillary, and follicular) thyroid carcinoma
• Randomized phase III clinical trials supporting a TKI benefit in thyroid cancer are currently unavailable; thus, there are no specific regimens
• Doxorubicin 60 mg/m2 as monotherapy or in combination with cisplatin 40 mg/m2 may be considered for patients who cannot tolerate TKIs or in whom TKIs have failed; however, the efficacy of these, and other cytotoxic drugs, is very limited


Locally recurrent or metastatic, progressive DTC treatment options are as follows:
Sorafenib and lenvatinib are VEGF inhibitors approved for DTC refractory to RAI treatment
Sorafenib: 400 mg PO q12h at least 1 h ac or 2 h pc
Lenvatinib: 24 mg PO once daily with or without food
Continue treatment until the patient is no longer clinically benefiting from therapy or until unacceptable toxicity occurs

Thyroid Cancer

Thyroid hormone withdrawal
By purposely not taking thyroid hormone replacement after total thyroidectomy for 4 to 6 weeks, the pituitary will naturally respond by increasing the TSH level. It does not "know" that there is no thyroid to make thyroid hormone and keeps trying to stimulate it more and more. In short, the patient is hypothyroid. Towards the end of the withdrawal phase, patients will be very hypothyroid and may feel very tired, fatigued, unmotivated, etc. Many physicians will put patients on the shorter acting thyroid hormone (T3, Cytomel) for 2 to 4 weeks followed by no hormone for 2 weeks in order to reduce the amount of time the patient is symptomatic. The TSH level is then checked to ensure adequate stimulation before RAI treatment. A TSH >30 is recommended before RAI. Thyroid hormone is restarted 2 to 3 days after taking the dose of RAI.

Recombinant TSH
Injections of recombinant TSH (or Thyrogen stimulation) involves giving a man-made form of TSH to stimulate the thyroid. This method allows patients to avoid the symptoms of hypothyroidism seen with thyroid hormone withdrawal therapy. Typically two doses of Thyrogen are given on two consecutive days followed by the RAI dose on the third day.

Lenvima™ (levatinib)
For the treatment of locally recurrent or metastatic, progressive, radioactive iodine-refractory differentiated thyroid cancer (DTC).
Lenvima™ (levatinib) 24 mg orally once daily with or without food until disease progression or unacceptable toxicity.
In a multicenter, randomized, double-blind, placebo-controlled clinical trial, treatment with lenvatinib (n = 261) significantly improved progression free survival (18.3 months vs. 3.6 months) and objective response rate (65% vs. 2%) compared with placebo (n = 131) in patients with locally recurrent or metastatic, progressive, radioactive iodine-refractory differentiated thyroid cancer.
Overall survival was not estimable in either group, with a hazard ratio of 0.73. Of note, 83% of patients randomly assigned to placebo crossed over to receive open-label lenvatinib upon progression, which may have affected overall survival.

Caprelsa® (vandetanib)
Caprelsa® (vandetanib tablets) is used to treat medullary thyroid cancer in adult patients whose tumour cannot be removed by surgery or has spread from the thyroid to other parts of the body. Like Lenvima™, Caprelsa® works by blocking the production of certain proteins in tumour cells, which slows down the growth of new blood vessels, cutting off the supply of nutrients and oxygen to the tumour to slow or prevent its growth. Caprelsa® also acts directly on cancer cells to kill them or slow down their rate of growth.

RAI Helps Defeat Thyroid Cancer

The five-year survival rate for people with localized thyroid cancer is 98%. The 10-year and 15-year survival rates are 97% and 95%, respectively. If the cancer has spread to a distant part of the body, the five-year survival rate is 54%.

In most cases, patients diagnosed with thyroid cancer are treated with surgical removal of the thyroid gland (thyroidectomy). Following removal of the gland and based on their established risk profile, appropriately selected patients are then treated with a procedure known as remnant ablation involving administration of radioiodine (RAI) to identify and kill any remaining cancer cells. (RAI is also often used in adjuvant therapy to identify and destroy unproven residual thyroid cancer and in therapy to treat persistent disease in high-risk patients.) According to guidelines set in 2015 by the American Thyroid Association, remnant ablation with RAI can be considered for low-risk patients and is generally favored for low- to intermediate-risk patients and recommended for patients at high risk of recurrence.

The thyroid gland absorbs nearly all of the iodine circulating systemically in the body. As a result, when RAI is administered in patients, it has the targeted ability to concentrate in and kill thyroid cells, including any residual thyroid cancer cells. For remnant ablation with RAI to be effective, patients must have sufficient levels of thyroid-stimulating hormone (TSH or thyrotropin) in the blood. This hormone stimulates any remaining thyroid tissue to take up the RAI.

If the thyroid gland has been removed, one widely used method to raise TSH levels is to stop a patient's treatment with thyroid hormone replacement therapy for several weeks. This causes levels of TSH to rise but also increases the risk of a condition known as hypothyroidism.

Managing the RAI Ablation Process
In an empiric treatment model, following thyroidectomy treatment with thyroid hormone replacement therapy is either not initiated or is stopped to allow TSH levels to increase to approximately 25 to 30 mU/L. Patients are then treated with RAI (I-131) at doses ranging from 30 to 100 mCi. Between three and seven days following administration of recombinant human TSH (rhTSH), a whole body scan (WBS) is performed to identify any areas where the iodine was picked up.

In patients who continue treatment with thyroid hormone who are not hypothyroid, rhTSH is administered on days one and two to provide the necessary TSH stimulation. On day three the dose of I-131 (30 to 100 mCi) is given and WBS is performed between three and seven days later. Research has shown that rates of remnant ablation are comparable for patients treated with hormone withdrawal and for patients who continue treatment with thyroid hormone replacement therapy in conjunction with administration of rhTSH.

In an alternative treatment model, a diagnostic preablation scan is performed in patients who are made hypothyroid or in patients who continue treatment with thyroid replacement hormone in conjunction with rhTSH. Patients are then given a tracer dose 4 mCi of I-131 and WBS is performed. In a study of 320 patients with differentiated thyroid cancer, use of preablation WBS with SPECT/CT technology resulted in changes in assessments of risk of recurrence in 15% of patients,6 and in diagnosis of stage of disease in 4% of younger patients and 25% of older patients.
(Note: Dx scans detected regional metastases in 35% of patients, and distant metastases in 8% of patients. Information acquired with Dx scans changed staging in 4% of younger, and 25% of older patients. Preablation scans with SPECT/CT contribute to staging of thyroid cancer. Identification of regional and distant metastases prior to radioiodine therapy has significant potential to alter patient management.)

Recent studies have also demonstrated that use of RAI ablation is similarly effective with or without administration of treatment with rhTSH to reduce the risk of hypothyroidism. Among patients receiving RAI post total thyroidectomy, low-risk patients who show uptake of RAI outside of the thyroid bed, as well as all intermediate- and high-risk patients, should receive follow-up diagnostic testing including TSH stimulated WBS at six to 18 months.

In addition to reducing a risk of hypothyroidism, use of rhTSH has also been shown to have an impact on RAI kinetics. RAI has a longer half-time in remnant tissue after rhTSH compared with thyroid hormone withdrawal, while the differences in uptake and residence time are not statistically significant. In patients treated with RAI with rhTSH for TSH stimulation, mean residence times of RAI in tissue and blood were significantly lower compared with patients utilizing thyroid hormone withdrawal as the method for TSH stimulation. This suggests use of rhTSH may lead to less of an undesired effect of RAI on the remainder of the body.

The safety profile in patients receiving rhTSH either for diagnostic purposes or as adjunctive treatment for RAI ablation in patients who have undergone a thyroidectomy does not differ. In the combined clinical trials, reactions reported in patients greater than or equal to 1% include nausea, headache, fatigue, vomiting, dizziness, and asthenia.

Options in management of RAI have been further supported by the introduction of advanced imaging modalities able to provide more precise information related to uptake of RAI. SPECT/CT combines the information from a nuclear medicine SPECT with imaging from CT to support enhanced observation and staging of neoplastic disease. SPECT/CT RAI imaging can provide better anatomic localization of RAI uptake and distinguish between likely tumors and nonspecific uptake. Results from SPECT/CT can be used to confirm designations and modifications in patient risk assessments and correlating treatment protocols.6 In addition, updated collimators are available that can enhance imaging and address challenges associated with use of older cameras that produce lower-quality scans.

Conclusion
The prospects for long-term survival in thyroid cancer reinforce the need for clinicians and radiologists to continually assess the available interventional strategies and technologies that can help patients remain cancer-free while maintaining both overall health and quality of life. The application of different approaches in the administration of RAI coupled with access to advanced imaging technologies and procedures represent important considerations in development of treatment protocols able to support optimal outcomes for patients in the years ahead.

Thyroid Stimulating Hormone (TSH) Suppression

Patients treated for differentiated thyroid cancer take a daily thyroid hormone replacement pill called levothyroxine (also known as T4). They take it both to avoid hypothyroidism (underactive thyroid condition) and to prevent growth or recurrence of their thyroid cancer.

Usually they receive a T4 dose large enough to suppress their blood level of thyroid stimulating hormone (TSH) below the normal TSH range. This is called TSH suppression. The ATA and ETA guidelines suggest TSH suppression when a patient has active tumor or has a very aggressive tumor that has been treated with surgery and radioactive iodine (I 131).

However, about 85% of patients can be shown to be free of disease after initial tumor treatment by testing the patient' serum thyroglobulin levels and performing neck ultrasonography. When the patient is felt to be free of tumor on this basis, the ATA and ETA guidelines suggest maintaining the blood TSH in the low normal level, which is particularly important in children.

Patients whose thyroid glands have been removed will need to be on levothyroxine medication for the rest of their lives. The medication, which is necessary for maintaining a person's full health, must be taken on an empty stomach. Generally, it should not be taken with other drugs, since a large number of drugs interfere with thyroid hormone getting into the blood stream. Drugs as common as vitamins with iron can do this. It is necessary to check with the pharmacist and physician when new drugs are being prescribed.

There are several brands of levothyroxine. Thyroid cancer specialist physicians recommend that patients stay on the same brand and not change unless a re-test of their blood is done 6 weeks later, because the brands may not result in the same TSH level, even at the same dose.

The American Thyroid Association Guidelines (2009) have more information and recommendations. They are linked from the web site in the sections titled Newly Diagnosed and Thyroid Cancer Types.

TSH in Initial Management and Long-Term Management

The American Thyroid Association's Guidelines (2009) make several recommendations regarding TSH.

For initial TSH suppression, for high-risk and intermediate-risk patients, the guidelines recommend initial TSH below 0.1 mU/L, and, for low-risk patients TSH at or slightly below the lower limit of normal (0.1–0.5 mU/L). (Recommendation 40).

For long-term management, the guidelines recommend (Recommendation 49):

In patients with persistent disease, the serum TSH should be maintained below 0.1mU=L indefinitely in the absence of specific contraindications. In patients who are clinically and biochemically free of disease but who presented with high risk disease, consideration should be given to maintaining TSH suppressive therapy to achieve serum TSH levels of 0.1–0.5mU=L for 5–10 years. In patients free of disease, especially those at low risk for recurrence, the serum TSH may be kept within the low normal range (0.3–2mU=L). In patients who have not undergone remnant ablation who are clinically free of disease and have undetectable suppressed serum Tg and normal neck ultrasound, the serum TSH may be allowed to rise to the low normal range (0.3–2mU=L).

About 85% of postoperative patients are low-risk, according to the guidelines.

The Guidelines, plus other information linked in the Newly Diagnosed section explain low, intermediate, and high risk of persistent or recurrent disease.