Other Considerations

Differential Diagnoses

• Nodular Non-toxic Goiter• Graves’ Disease• Toxic Multinodular Goiter• Toxic Adenoma• Solitary Thyroid Nodule

Nodular Non-toxic GoiterFAMILIAL GOITER ENDEMIC GOITER SPORADIC

GOITERInherited enzyme defectImpaired iodine metabolismUsually associated with hypothyroidism

Due to iodine-deficient dietMountainous regionsintake of substances (goitrogens) that inhibit production of thyroid hormone—common goitrogens include foods such as cabbage, turnips, brussel sprouts, seaweed, and milletTx: iodized salt

No definite cause can be established

• Enlargement of the thyroid gland• No toxicity; no cancer• The following factors increase your chance of

developing nontoxic goiter: – Sex: female (nontoxic goiter is more common in

women than men)– Age: over 40 years

Reference: http://www.mbmc.org/healthgate/GetHGContent.aspx

SYMPTOMS

• Nontoxic goiters usually do not have noticeable symptoms.

• Swelling on the neck• Breathing difficulties, coughing, or wheezing

with large goiter• Difficulty swallowing with large goiter• Feeling of pressure on the neck• Hoarseness

MANAGEMENT

• A goiter only needs to be treated if it is causing symptoms.

• Treatments for an enlarged thyroid include:– Radioactive iodine to shrink the gland, particularly if the

thyroid is producing too much thyroid hormone– Surgery (thyroidectomy) to remove all or part of the gland– Small doses of Lugol's iodine or potassium iodine solution if

the goiter is due to iodine deficiency– Treatment with thyroid hormone supplements if the goiter

is due to underactive thyroid

Reference: http://www.nlm.nih.gov/medlineplus/ency/article/001178.htm

INDICATIONS FOR SURGERY

• Huge goiter which is cosmetically unacceptable

• Compression symptoms• Suspicion of malignancy

GRAVES’ DISEASE• A type of hyperthyroidism, is caused

by a generalized overactivity of the entire thyroid gland.

• An autoimmune disease; thyroid-stimulating antibodies directed at TSH receptors on follicular cells.

• It is named for Robert Graves, an Irish physician, who was the first to describe this form of hyperthyroidism about 150 years ago.

ETIOLOGY

• The trigger for auto-antibody production is not known.

• Genetic predisposition – HLA DR3• Since Graves' disease is an autoimmune disease

which appears suddenly, often quite late in life, it is thought that a viral or infection may trigger antibodies which cross-react with the human TSH receptor (a phenomenon known as antigenic mimicry, also seen in some cases of Type I diabetes).– Yersinia enterocolitica

Reference: http://en.wikipedia.org/wiki/Graves%27_disease

CLINICAL FEATURES

• Triad:– Goiter including the

pyramidal lobe– Thyrotoxicosis– Exophthalmos

• Symptoms:• Heat intolerance• Thirst• Sweating• Weight loss despite

adequate caloric intake• Amenorrhea• Tachycardia or atrial

fibrillation• Congestive heart failure

• PE: Weight loss Flushing Warm and moist skin Inappropriate sweating Tachycardia Widening of pulse pressure Fine tremor Muscle wasting Hyperactive tendon reflexes Pretibial myexedema Gynecomastia Audible bruit over the gland

• Laboratory Findings: Decreased TSH Increased circulating T3/T4

levels Increased circulating thyroid

autoantibodies Thyroid stimulating

immunoglobulins (TSI) Tyhroid stimulating

antibodies (TSAb) Radioactive iodine scan

shows diffuse uptake through the gland of 45-90 percent.

MANAGEMENT

• Medical:Propylthiouracil (PTU)Methimazole (Tapazole)CarbimazoleBeta-blockers (Propanolol)

• Relapse rate in 12-18 months• Risk for fetal goiter, hypothyroidism• No morbidity related after surgery• Treatment of choice for small goiters and

pregnant patients (PTU)• Euthyroid state is achieved in 4-6 weeks

• Radioactive Iodine– Ease of treatment– Highly effective especially in diffuse goiters– No morbidity related to surgery– Treatment of choice for failed surgical

management– The effect is seen in 1.5-4 months– Standard dose = 10 mCl = 8500 cGy

• Surgery– Complete and permanent control of toxicity– Rapid control of symptoms– Removal of mass– Treatment of choice for huge goiters– Needs pre-operative preparation– Overall morbidity of 1-2%

Toxic Multinodular Goiter• Usually occur in individuals older than 50 years of age who

often have a prior history of a nontoxic multinodular goiter• Over several years, enough thyroid nodules become

autonomous to cause hyperthyroidism.• Similar to Graves’ disease, but symptoms and signs of

hyperthyroidism are less severe and extrathyroidal manifestations are absent.

• May present with atrial fibrillation or palpitations, tachycardia, nervousness, tremor or weight loss.

• Low TSH, normal or minimally increased T4, elevated T3, T3>T4.

Toxic Multinodular Goiter• Thyroid scan – heterogenous uptake with multiple regions of

increased and decreased uptake.• 24hr uptake of radioiodine may not be increased. • Management

– Antithyroid drugs + beta blockers – normalize thyroid function and address the clinical features of thyrotoxicosis, but often stimulates the growth of the goiter; spontaneous remission does not occur.

– Radioiodine – treat areas of autonomy, decrease the mass of the goiter

– A trial of radioiodine should be considered before subjecting patients to surgery.

Toxic Multinodular Goiter

• Surgery– Definitive treatment of underlying thyrotoxicosis

and goiter.– Subtotal thyroidectomy is the standard procedure.– Patients should be rendered euthyroid using

antithyroid drugs before operation.

Toxic Adenoma

• A solitary, autonomously functioning thyroid nodule

• Typically occurs in younger patients• (+) thyroid nodule with symptoms of

hyperthyroidism• Size is at least 3cm before hyperthyroidism

occurs.• Absent clinical features suggestive of Graves’

disease or other causes of thyrotoxicosis

Toxic Adenoma

• Thyroid scan – definitive diagnostic test– Focal uptake in the

hyperfunctioning nodules– Diminished uptake in the

remained of the gland• Suppression of the activity

of the normal thyroid

Toxic Adenoma

• Radioiodine ablation – treatment of choice– 131I is concentrated in the hyperfunctioning

nodule with minimal uptake and damage to normal thyroid tissue.

– Relatively large doses – correct thyrotoxicosis in about 75% of patients within 3 months.

– Hypothyroidism occurs in <10% of patients over the next 5 years.

Toxic Adenoma

• Surgical resection– Limited to enucleation of the adenoma– Lobectomy– Preservation of thyroid function– Low risk of hypoparathyroidism– Low risk of damage to the recurrent laryngeal

nerve

Toxic Adenoma

• Medical therapy using antithyroid drugs and beta blockers – normalize thyroid function but is not an optimal long term treatment

• Ethanol injection under ultrasound guidance– Repeated injections – often >5 sessions– Reduce nodule size

Solitary Thyroid Nodule• Present in approximately 4 percent of

the population• Pain is unusual. When present, it

should raise suspicion for intrathyroidal hemorrhage in a benign nodule, thyroiditis, or malignancy.

• History of hoarseness - may be secondary to malignant involvement of the recurrent laryngeal nerves

• Risk factors for malignancy – exposure to ionizing radiation and family history of thyroid and other malignancies associated with thyroid cancer.

Solitary Thyroid Nodule• Mass moves with swallowing.• Hard, gritty of fixed nodules are more

likely to be malignant. • Most are euthyroid.• If a patient with a nodule is found to be

hyperthyroid, the risk of malignancy is approximately 1 percent.

• FNAB – most important diagnostic test– Benign – 65% (includes cysts and colloid

nodules)– Suspicious – 20%– Malignant – 5%– Nondiagnostic – 10%

Solitary Thyroid Nodule• Ultrasound

– For detecting nonpalpable thyroid nodules– For differentiating solid from cystic

nodules– For diagnosing suspicious nodules with

microcalcifications– For identifying adjacent lymphadenopathy

• CT and MRI – unnecessary in except for large, fixed, or substernal lesions.

• 123I or 99mTc – rarely necessary, unless evaluating patients for “hot” or autonomous thyroid nodules

Solitary Thyroid Nodule• Malignant tumors – generally treated by total or near-

total thyroidectomy• Simple thyroid cysts - resolve with aspiration in

approximately 75 percent of cases• Unilateral thyroid lobectomy - if the cyst persists after three attempts at

aspiration

• Lobectomy – For cysts >4 cm in diameter– For complex cysts with solid and cystic components

Solitary Thyroid Nodule• Colloid nodule – should be observed with serial ultrasound and

Tg measurements– Repeat FNAB if nodule enlarges

• L-thyroxine – in doses sufficient to maintain a serum TSH level between 0.1 and 1.0 μU/mL.– 50% decrease in size

• Thyroidectomy – if a nodule enlarges on TSH suppression, causes compressive symptoms, or for cosmetic reasons– Exceptions: Patient who has had previous irradiation of the thyroid

gland or who has a family history of thyroid cancer.– In these patients total or near-total thyroidectomy is recommended.

• High incidence of thyroid cancer (≥ 40%) • Decreased reliability of FNA biopsy