**6. Management**

After establishing the diagnosis of GD treatment options include antithyroid drugs, radioiodine, and surgery. Although RAI is preferred in United States and ATDs in Europe but long term quality of life was found to be same in all three treatment group [47]. Selection of treatment depends on local availability, cost of treatment, presence of active GO and physician preference. The main goal of management is to normalize thyroid hormones level and make the patient asymptomatic.

#### **6.1 Pharmacological therapy**

### *6.1.1 Antithyroid drugs*

Thionamides are class of ATDs which inhibit thyroid peroxidase thereby inhibit thyroid hormone synthesis. Methimazole (MMI) and propylthiourecil (PTU) are used in United States where as Carbimazole (converted to methimazole in liver) is used in other part of world. MMI is preferred over PTU as initial therapy because of long duration of action and reduced risk of major side effect, except during first trimester of pregnancy where PTU is preferred because of lesser teratogenic effects [48]. Starting dose of MMI is 10 to 30 mg daily and of PTU is 50 to 10 mg three times daily. Dose of ATDs should be kept lowest to maintain T4 in normal range because higher doses are associated with high risk of adverse effect. Adverse effect of ATDs can be divided in minor allergic reaction and serious allergic/toxic effects agranulocytosis, liver injury and vacuities [48–52]. Hepatotoxicity and agranulocytosis are seen more commonly with propylthiouracil. Initial complete blood cell count and liver function test required before starting these drugs and patient should be instructed to report if he develops high grade fever with sore throat. American Thyroid Association recommends ATDs should be continued for 12–18 months if chosen as primary therapy then can be discontinued if TSH and TRAb levels are normal. Remission rate with ADTs treatment is 40–60% and is not associated with duration and dose of ATDs. If patient becomes hyperthyroid after completion of treatment, RAI or thyroid surgery should be considered.

#### *6.1.2 Beta-adrenergic blocker*

Beta-adrenergic blocker should be given to all symptomatic thyrotoxic patients, especially elderly. Goal of beta blocker treatment is to decrease heart rate less than 90 per minute. Propranolol is preferred non-selective beta blocker which decreases deiodinationof T4 to T3 [53]. In patient with asthma, obstructive airway disease and Raynaud's phenomenon selective β1 blocker can be used with cautions. Calcium channel blockers verapamil and diltiazem can be used when β blockers are contraindicated [45].

#### *6.1.3 Lithium*

Lithium carbonate inhibits secretion of thyroid hormones. It does not decrease the efficacy of RAI so it can be used to control hyperthyroidism during RAI therapy or in patient who are allergic to ATDs.

#### *6.1.4 Cholestyramine*

It interfarewith enterohepatic circulation thereby decrease thyroid hormone leves rapidly. It can be used as adjunctive therapy in resistant thyrotoxicosis.

#### **6.2 Radioactive iodine**

RAI is one of definitive treatment for GD. It has been used for more than seven decade in the management of GD. Effect of ionizing radiation leads to cellular death and consequently reduction in functioning thyroid tissue and thyroid size. The goal

#### *Graves' Disease: A Review DOI: http://dx.doi.org/10.5772/intechopen.98686*

of RAI is to render the patient hypothyroid for that 10–15 mci dose is sufficient in most of the patients. RAI can be used as primary therapy in mild cases but in severe thyrotoxic patient β blockers and ATDs are used first to render the patient euthyroid to avoid radiation induced thyroiditis. ATDs should be discontinued 2–3 days prior and till 3–7 day of RAI treatment to enhance the efficacy of treatment. Regular follow up should be at 4–6 weeks interval with biochemical testing include TSH, FT4 and T3 till 6 months or till patient become hypothyroid. Around 40% of patient treated with RAI become hypothyroid by 8 weeks and 80% by 16 weeks [54]. Levothyroxine replacement therapy should be started once patient become hypothyroid. Most of studies found no increase in prevalence of thyroid cancer or secondary malignancy in RAI treated patients. RAI is associated with development and worsening of orbitopathy as compare to ATDs and thyroid surgery [55, 56]. So presence of orbitopathy may influence the treatment option.
