Thyroid cancer

Thyroid cancer is the most common malignancy of the endocrine system

-Most thyroid cancers occur in the young with only one-third of cases occurring after age 55

-Thyroid cancer can be of follicular cell origin or C-cell origin or lymphoid origin. 

Originating from follicular cells 

Papillary 80% 

Follicular 11% 

Hürthle cell 3% 

Anaplastic 2% 

Originating from C-cells or parafollicular cells 

Medullary 4%

Originating from lymphoid cells 

Thyroid lymphoma 1% 

Most of these carcinomas are treated by surgery, radioiodine, and levothyroxine to suppress TSH

Toxic multinodular goiter


Toxic multinodular goiter refers to autonomous hyperfunctioning thyroid nodules that produce hyperthyroidism 

-it is more common in women over the age of 60 and in iodine-deficient regions

-it is the second most common cause of hyperthyroidism after Graves disease 

Symptoms & Signs 

Symptoms and signs of hyperthyroidism are similar to Graves’ disease: weight loss, nervousness, weakness, tremors, sweats, tachycardia, heart failure, arrhythmias, atrial fibrillation, congestive heart failure 

Physical examination reveals a multinodular goiter which may extend substernally


Labs: low or undetectable TSH, elevation in serum serum T3 levels, with less striking elevation of serum T4

Radioiodine scan: multiple functioning nodules in the gland with iodine localized to active nodules


methimazole (preferable) or propylthiouracil followed by subtotal thyroidectomy; RAI therapy 

thyroid nodules & cancer


-Thyroid nodules is the most common endocrinopathy 

-They are extremely common, particularly among women

– About 90% of palpable thyroid nodules are benign adenomas, colloid nodules, or cysts, but some are malignancies 

-Most patients with a thyroid nodule are euthyroid, but some are hypothyroid or hyperthyroid 

-The most common neoplasm is the follicular adenoma (benign thyroid nodule) 

– A thyroid nodule is more likely to be a cancer in a man than in a woman and in young patients (under 20 years) and older patients (over 60 years)

Symptoms & Signs 

-Thyroid nodules usually are asymptomatic

-neck discomfort, dysphagia, choking sensation, hoarseness

-Large substernal goiters can cause superior vena cava syndrome, characterized by facial erythema and jugular vein distention that progress to cyanosis and facial edema when both arms are kept raised over the head (Pemberton sign)


-Serum TSH, thyroid ultrasound, Fine-needle aspiration (FNA)

-radionuclide thyroid scanning

-the diagnostic procedure of choice is FNA 


Medical therapy, levothyroxine suppressive therapy, surgery, RAI therapy, Ultrasound-guided radiofrequency ablation

Thyroid surgery complications

-thyroid surgery is indicated for patients with Graves disease, toxic multinodular goiter, toxic adenoma, Reidel’s thyroiditis, goiter, thyroid nodules benign and malignant thyroid tumors 

-Complications of thyroid surgery: injury to recurrent laryngeal nerve with resultant vocal cord paralysis, hypoparathyroidism, injury to cervical sympathetic trunk resulting in Horner’s syndrome 

Radioactive iodine

Radioactive iodine-131 is used for treatment of thyrotoxicosis, thyroid cancer and for diagnostic thyroid scanning

-It is effective in ablating the thyroid gland and producing permanent hypothyroidism

-In North America, RAI forms the mainstay of Graves’ disease 

– the only isotope used for treatment of thyrotoxicosis is 131I

-RAI is most often used in older patients or those who have relapsed after medical or surgical therapy or in whom medical or surgical therapy is contraindicated 

-Radioactive iodine should not be given to pregnant women due to the potential teratogenic effects for the fetus’s growth

-all women of childbearing age must have a negative pregnancy test prior to treatment

-After RAI, wait for 6 months before conceiving 

-Absolute contraindications to RAI: pregnancy or planning pregnancy within 6 months of treatment, breastfeeding 

-Relative contraindications to RAI: children, adolescents, those with ophthalmopathy 

-After RAI treatment, most patients become euthyroid within 2 months 

-The most common complication of RAI is hypothyroidism 

-RAI can exacerbate Graves’ ophthalmopathy especially if the patient is a smoker

Grave’s Disease


Grave’s disease is an autoimmune thyroid disorder characterized

by circulating antibodies that stimulate the TSH receptor, resulting in the increase in synthesis and release of thyroid hormones 

-it is the most common cause of hyperthyroidism and thyrotoxicosis 

-It is more common in women than in men with onset usually between 20 and 40 years of age 

-Dietary iodine supplementation can trigger Graves disease

-Thyrotoxicosis: clinical state resulting from inappropriately high thyroid hormone levels

hyperthyroidism: thyrotoxicosis caused by elevated synthesis and secretion of thyroid hormone

Symptoms & Signs

General: fatigue, fever, heat intolerance, weight change, irritability, intolerance    

Thyroid: diffusely enlarged thyroid often with a loud bruit 

Eyes: infiltrative ophthalmopathy (Graves exophthalmos),spasm of the upper eyelid revealing the sclera above the corneoscleral limbus (Dalrymple’s sign) , lid lag with downward gaze (von Graefe sign), a staring appearance (Kocher sign), conjunctival swelling and congestion, keratitis, papilledema, permanent visual loss 

Nervous: Restlessness, nervousness, fine resting tremors 

Cardiac: palpitations, angina,exertional dyspnea, atrial fibrillation, premature atrial contractions, atrial tachycardia, ischemic or valvular heart disease, pulmonary hypertension    

Gastrointestinal: dysphagia, frequent bowel movements, diarrhea  

Musculoskeletal: muscle weakness, cramps, osteoporosis  

Dermatologic: facial flushing, moist warm skin, pruritis, increased sweating, fine hair, onycholysis,bony involvement leads to subperiosteal bone formation and swelling in the metacarpals (thyroid acropachy), infiltrative dermopathy (pretibial myxedema)

Genitourinary: menstrual irregularities  amenorrhea, decreased fertility, and an increased incidence of miscarriages


Serum TSH: low or undetectable 

free T4 or T3: elevated 

Thyroid receptor antibodies (TRAbs): elevated 

RAI scan: elevated uptake and a homogeneous pattern 

Technetium scintigraphy: increased or normal thyroid uptake of technetium 


Symptomatic treatment: beta blockers, calcium blockers 

Antithyroid drugs: Methimazole, carbimazole, propylthiouracil 

Radioactive iodine (131I, RAI): the most commonly prescribed treatment in the United States, but is contraindicated in pregnancy or with breastfeeding 

surgery: a total resection of one lobe and a subtotal resection of the other lobe

Euthyroid sick syndrome


Euthyroid sick syndrome is a clinical condition characterized by low thyroid hormone levels  in clinically euthyroid patients with nonthyroidal systemic illness

-it can be precipitated by stresses such as chronic liver failure, renal failure, malnutrition, fasting, starvation, anorexia, diabetic ketosis, and sepsis 

-The first testing abnormality to manifest is low T3 level

Symptoms & Signs 

No signs or symptoms of thyroid dysfunction 


Patient’s setting: critical illness, chronic illness, ICU admission etc

No clinical manifestations of thyroid dysfunction 

Labs: TSH: Normal or low 

T4 : Normal or low 

T3, total and free : Low 

Reverse T3 (rT3): High or normal 


-Treat the underlying nonthyroid illness 

-Thyroid hormone replacement is not beneficial