thyroid disorders
What Is the first-line treatment for hypoparathyroidism?
Answer: Calcium and vitamin D supplementation.
What finding on a radioactive iodine scan would be most consistent with the diagnosis of Graves disease?
Answer: Diffuse uptake of iodine.
What are the two types of cells that make up the thyroid, and what are their functions?
Answer: Follicular cells, which secrete thyroid hormones T3 and T4, and parafollicular cells (also known as C cells), which secrete calcitonin.
Which type of thyroid cancer is most common in patients consuming low iodine diets?
Answer: Follicular thyroid cancer.
In what thyroid disorder can a thyroid bruit often be heard?
Answer: Graves disease (hyperthyroidism).
What are some causes of secondary or tertiary hypothyroidism?
Answer: Hypothalamic or pituitary disease, pituitary tumor, and other associated hormone deficiencies that cause insufficient stimulation of thyroid-stimulating hormone from the pituitary gland.
What diseases are associated with multiple endocrine neoplasia 2A?
Answer: Medullary thyroid cancer, pheochromocytoma, and hyperparathyroidism.
What type of cells does medullary thyroid cancer arise from?
Answer: Parafollicular cells.
Graves Disease
Autoimmune Hyperthyroidism Goiter Exophthalmos Pretibial edema Medications, radioactive iodine, surgery
follicular thyroid cancer
Follicular thyroid cancer is the second most common thyroid cancer. It is associated with iodine deficiency and is more common in ages 40-70. It is more aggressive than papillary thyroid cancer, however, it is slow growing. Thyroglobulin is a tumor marker for follicular thyroid cancer also. Metastases are commonly found in cervical lymph nodes, bones, and lungs. Patients with follicular thyroid cancer also have an excellent prognosis after thyroidectomy.
Hyperthyroidism Sx: PE: Labs: Most commonly caused by Tx:
Hyperthyroidism Sx: heat intolerance, palpitations, weight loss, tachycardia, and anxiety PE: hyperreflexia, goiter, exophthalmos, pretibial edema Labs: low TSH and high free T4 Most commonly caused by Graves disease (autoimmune against TSH receptor) Tx: methimazole or PTU PTU in the first trimester of pregnancy
Hypothyroidism Patient presents with generalized PE will show Labs will show Most commonly caused by Treatment is Takes about_____ to see treatment effects Monitor Hashimoto: risk factor for
Hypothyroidism Patient presents with generalized weakness, fatigue, facial swelling, constipation, cold intolerance, and weight gain PE will show periorbital edema, dry skin, and coarse brittle hair Labs will show high TSH and low free T4, antithyroid peroxidase and antithyroglobulin autoantibodies Most commonly caused by Hashimoto thyroiditis Treatment is levothyroxine Takes about 6 weeks to see treatment effectsMonitor TSH Hashimoto: risk factor for non-Hodgkin lymphoma
medullary thyroid cancer
Medullary thyroid cancer is rarer than papillary and follicular thyroid cancers. It is associated with multiple endocrine neoplasia type 2 (medullary thyroid cancer, hyperparathyroidism, and pheochromocytoma). Patients may report flushing, diarrhea, and fatigue as symptoms of medullary thyroid cancer. It is more aggressive than papillary and follicular thyroid cancers, and early metastasis to local tissue and late metastasis may occur in bones, liver, adrenals, or lungs. Treatment still includes a total thyroidectomy and complete dissection of cervical lymph nodes. Calcitonin levels are used to monitor for residual disease after treatment or for recurrence of medullary thyroid cancer
Primary Hyperparathyroidism Causes: ? PTH, ? Ca, ? phosphorus ? Ca → Only curative Rx:
Primary Hyperparathyroidism Causes: parathyroid adenoma > gland hyperplasia, cancer ↑ PTH, ↑ Ca, ↓ phosphorus ↑ Ca → stones, bones, groans, psychiatric overtones Only curative Rx: parathyroidectomy
anaplastic thyroid carcinoma
The last type of thyroid cancer is anaplastic thyroid carcinoma. It is the least common type, however, it is the most aggressive. Anaplastic thyroid cancer is most common in men over the age of 65. It grows rapidly and may invade local tissues, including the trachea. Patients may report dysphagia and hoarseness. It metastasizes early to local and distant sites. Patients with anaplastic thyroid cancer have a poor prognosis with only a 10% survival rate three years after diagnosis. Treatment includes radiation and chemotherapy. Many patients also require a tracheostomy to maintain their airway. Any patient who undergoes a total thyroidectomy needs to have levothyroxine initiated.
papillary thyroid cancer
The most common type of thyroid cancer is papillary thyroid cancer. It most commonly occurs in young women and is the least aggressive of all thyroid cancers. The greatest risk factor for papillary thyroid cancer is head or neck radiation exposure as a child. Most patients will have microscopic metastasis to cervical lymph nodes, however, distant metastases are uncommon. Thyroglobulin is a tumor marker present in metastatic papillary thyroid cancer and can be monitored for indications of successful treatment of recurrence. Patients with papillary thyroid cancer have an excellent prognosis after a thyroidectomy and neck lymph node dissection
Thyroid Nodules 90% of thyroid nodules are ____ Risk factors for malignancy: Dx TSH low: TSH normal or high: Sonographic features suggestive of malignancy: Cytology (Bethesda classification) Benign nodules: Intermediate: Suspicious for malignancy or malignant:
Thyroid Nodules 90% of thyroid nodules are benign Risk factors for malignancy: family history of thyroid cancer, male sex, age < 20 or > 70, radiation exposure, fixed or firm nodule, symptoms of compression (hoarseness) Dx TSH low: radionuclide scan and T3, FT4, do not biopsy hot nodule, treat for hyperthyroidism TSH normal or high: thyroid ultrasound and FNA (fine-needle aspiration) if nodule has suspicious features and is ≥ 1cm Sonographic features suggestive of malignancy: solid hypoechoic nodule or hypoechoic component, irregular margins, microcalcifications, taller than wide shape, rim calcifications, extrathyroidal extensionPurely cystic nodules have < 1% risk of malignancy, no biopsy Cytology (Bethesda classification)Benign nodules: monitor with ultrasound in 12 monthsIntermediate: repeat FNA, molecular testing, diagnostic lobectomySuspicious for malignancy or malignant: surgery
Which of the following physical exam findings is most consistent with a benign thyroid nodule?
a smooth, well defined mobile nodule Thyroid nodules are common in the general population and often affect women more than men. Most thyroid nodules are benign adenoma, colloid nodules, or cysts, but they can also be primary thyroid cancer and metastatic malignancy. They must be greater than 1 cm in diameter to be palpated and are discovered incidentally during self-exam, physical exam, or through imaging. Large nodules (> 1 cm in diameter) and some small nodules (those with high-risk features and present in a patient at high risk for thyroid cancer) warrant further evaluation for function and malignancy. The risk factors for a thyroid nodule becoming malignant include large-sized nodules; presence of vocal cord paralysis, hoarseness, or cervical lymphadenopathy; male sex; prior head-neck radiation; total body irradiation for bone marrow transplantation; exposure to radioactive fallout as a child; a family history of thyroid cancer; or a thyroid cancer syndrome (such as Cowden syndrome, multiple endocrine neoplasia type 2, familial polyposis, or Carney syndrome). The features of a nodule that decrease the likelihood of malignancy include a smooth, well-defined mobile nodule, a nodule found in older women, and a nodule seen in multinodular goiter. Patients with small nodules are often asymptomatic. As the nodules become larger, they may compress adjacent structures causing discomfort, dysphagia, dyspnea, superior vena cava syndrome, or hoarseness (when it compresses the recurrent laryngeal nerve). Benign nodules likely appear on physical exam as smooth, well defined, and mobile (which indicates they are nonadherent to underlying structures), and they move when the patient swallows. Malignant nodules are likely to present as large nodules (> 4 cm), firm, and fixed in place, and they are less likely to move when a patient swallows. Furthermore, malignant nodules are more likely to grow at least 2 mm annually than benign nodules. Conversely, nodules that appear spongiform or cystic are more likely to be benign. Thyroid nodularity increases with increasing age. The risk of progression of a nodule to cancer is higher in men than women and is higher in individuals over the age of 60 years and under 30 years. The first laboratory study that should be obtained is a serum TSH level. If the serum TSH is subnormal, a radionuclide thyroid scan using either iodine-123 or technetium-99m must be performed to determine whether or not the nodule is functional. Cold nodules (those with no uptake of the radiotracer) are hypofunctioning and are concerning for thyroid malignancy. These nodules should be evaluated initially with fine-needle aspiration (FNA) and, if found to be cancerous, should undergo surgical resection. Hot nodules (those with increased uptake) are hyperfunctioning and carry a lower risk for malignancy. If TSH is normal or high and the nodules meet sonographic criteria for sampling, the next step in diagnosis is a palpation or ultrasound-guided FNA. High-resolution ultrasonography is the imaging modality of choice for assessing thyroid nodules. It can detect thyroid lesions, determine the size and structure of the nodules, and assess diffuse changes in the gland. The ultrasound features that increase the likelihood of malignancy include irregular or indistinct margins, heterogeneous echogenicity, intranodular vascular margins, microcalcifications, complex cyst patterns, or size greater than 1 cm. All nodules suspicious for malignancy should be further evaluated using ultrasound-guided FNA. Treatment of thyroid nodules depends on whether or not they are malignant. Benign nodules should be observed with repeat ultrasound in 6 to 18 months. Malignant nodules can be surgically removed by direct lobectomy or near-total thyroidectomy.
An 18-year-old woman presents to the office for a painful lump at the base of her throat that has gotten increasingly tender over the past few weeks. She does not have a fever and does not have pain with swallowing or changes in her voice. Upon physical exam, there is a palpable nodule noted to the right lobe of the thyroid that is tender to palpation. A thyroid scintigraphy is ordered, showing decreased uptake of iodine compared to surrounding thyroid tissue. Which of the following nodules do these findings describe?
cold nodule Thyroid nodules are characterized by lesions that are radiologically differentiated from the surrounding thyroid tissue. Most cases are benign, with a small percentage found to be malignant. It is a widespread disease in the United States, with more nodules found in women than men, although men are more likely to have malignant disease. Most patients with thyroid nodules are asymptomatic. Nodules are usually found on physical exam or incidentally on imaging studies (e.g., ultrasonography or magnetic resonance imaging) performed for other diseases. Benign diseases include colloid nodules, cysts, hyperplasia, thyroiditis, or benign tumors. Benign disease will be found in patients with a history of autoimmune disease (e.g., Hashimoto thyroiditis), a family history of benign thyroid disease, or personal history of hypo- or hyperthyroidism. The nodule is more likely to be benign if the nodule is painful or tender to touch and if it is soft, smooth, and mobile upon palpation. Malignant causes include papillary carcinoma, follicular carcinoma, medullary carcinoma, and metastatic tumors. The risk of malignancy is increased in male patients, those younger than 20 years or older than 70 years, those with a history of neck irradiation or thyroid carcinoma, or those who have a family history of thyroid malignancy. The risk is also increased if the patient has associated difficulty swallowing, vocal changes, or cervical lymphadenopathy; if the nodule is firm, hard, or immobile on physical exam; if the nodule has rapid growth; or if it is larger than 4 cm in size. Patients should have a thyroid-stimulating hormone (TSH) assay, serum thyroxine (T4), and triiodothyronine (T3) to screen for hypothyroidism or hyperthyroidism. Patients with a family history of Hashimoto thyroiditis should have a serum antithyroid peroxidase (anti-TPO) antibody and antithyroglobulin (anti-Tg) antibody levels tested. Thyroid nodules can be evaluated by thyroid scintigraphy (radionuclide scanning), which will give information to describe the nodule in question as hot, warm, or cold, depending on its uptake of the radioactive isotope. Hot nodules take up more of the radioactive isotope than surrounding thyroid tissue and are indicative of autonomously functioning nodules, such as toxic adenomas or toxic multinodular goiters, and are rarely found to be malignant. Warm nodules indicate normal thyroid function, and cold nodules indicate low functional or nonfunctional thyroid tissue. Cold nodules will have a decreased uptake of radioactive isotope compared to surrounding thyroid tissue on scintigraphy. Warm or cold nodules have a higher risk of malignancy than hot nodules, with cold nodules carrying the highest risk. Ultrasonography-guided fine-needle aspiration biopsy with cytologic verification has the highest sensitivity and specificity for determining the diagnosis. A useful algorithm for evaluating thyroid nodules is if there is a lower than normal TSH finding. This is indicative of a hyperthyroid state and hyperfunctioning nodule, and a scintigraphy should be done next. If the serum TSH is high or normal, which indicates a low-functioning thyroid, a thyroid ultrasound should be performed next. A fine-needle aspiration should be performed if there is any suspicion for malignancy on ultrasound. Benign nodules can be followed with serial ultrasounds at 6-month intervals with possible repeat fine-needle aspiration biopsy to see if the nodule has changed. Patients with dysphagia or neck discomfort can be referred to a surgeon for removal. Malignant nodules should be referred for immediate evaluation and surgical treatment.
A 45-year-old man with a recent history of anterior neck surgery presents to the clinic with symptoms of generalized fatigue over the previous 2 months. Laboratory evaluation reveals a TSH of 15.1 mU/L and a free T4 of 0.6 ng/dL. Which of the following physical exam findings is likely present in this patient?
diastolic hypertension Hypothyroidism is the deficiency of circulating thyroxine, most commonly caused by autoimmune inflammation of the thyroid gland (Hashimoto thyroiditis). Other etiologies of hypothyroidism include iatrogenic causes (e.g., partial or complete thyroidectomy and radioablation of the thyroid) and secondary or tertiary hypothyroidism. Patients will commonly present with indolent symptoms, such as fatigue, dyspnea, lethargy, weakness, paresthesias, headaches, cold intolerance, constipation, and dry skin. Physical exam findings common in hypothyroidism include bradycardia, hair thinning, brittle nails, peripheral edema (myxedema), puffy eyes, goiter, delayed deep tendon reflexes, and diastolic hypertension. The typical patient presents with chronic symptoms that progress slowly. Myxedema crisis occurs with rapidly decreasing thyroid hormone levels or in patients with primary hypothyroidism who experience a secondary event (e.g., stroke, myocardial infarction, hypothermia, etc.). Patients with myxedema crisis will typically present with acute altered mental status, hypotension, hypothermia, and hypoventilation. In patients where hypothyroidism is suspected, laboratory evaluation should begin with a serum thyroid-stimulating hormone (TSH) and a serum thyroxine (T4) level. Elevated TSH and low T4 levels confirm primary hypothyroidism, whereas low TSH and T4 levels indicate secondary or tertiary hypothyroidism. An elevated TSH with a normal T4 likely represents subclinical hypothyroidism (early-stage Hashimoto thyroiditis). Patients with subclinical hypothyroidism will typically progress to hypothyroidism as the autoimmune process persists. In patients with laboratory evidence of primary hypothyroidism, serum thyroid autoantibodies can confirm Hashimoto thyroiditis. Replacement of synthetic thyroxine (levothyroxine) is the initial treatment of choice in those with confirmed hypothyroidism. Dosages of levothyroxine vary depending on the patient, therefore, serum measurement TSH should be monitored to measure treatment effect. Since thyroxine has a half-life of 5-7 days, the TSH should be checked 6 weeks after initiating levothyroxine and 6 weeks after any changes in the dose of the medication. For patients with subclinical hypothyroidism, no levothyroxine supplementation is needed, however, thyroid function should be repeated on a yearly basis to monitor for the onset of clinical hypothyroidism.
A 34-year-old woman presents to the office with findings of a new neck mass. She reports first noticing the lesion 3 months ago and believes it is slowly enlarging. She reports no pain, difficulty swallowing, or voice changes. On palpation, there is a 2.1 cm, well-circumscribed, fixed nodule that is nontender. The nodule appears to be oblong in shape. Blood work reveals a TSH of 8.1 mU/L but is otherwise normal. A thyroid ultrasound reveals an irregularly shaped nodule. What is the best diagnostic test to perform next for this patient?
fine needle aspiration The thyroid is an endocrine gland located in the anterior neck overlying the trachea and cricoid process. It is a butterfly-shaped gland made up of a pyramidal lobe, right lobe, left lobe, and the isthmus. On the cellular level, the thyroid contains two types of secretory cells. Follicular cells secrete thyroxine (or T4) and triiodothyronine (T3). Parafollicular cells secrete thyrocalcitonin. The thyroid gland is responsible for hormone secretion and the regulation of numerous physiologic functions throughout the body. Thyroid nodules are common neck masses that can be found in any lobe of the thyroid. With the introduction of advanced ultrasonography, it has been determined that thyroid nodules may be found in up to 60% of the population. Of these, up to 15% of nodules may be malignant. A palpable thyroid nodule may occur in up to 10% of the population. Risk factors for the development of thyroid nodules include ionizing radiation, tobacco use, alcohol use, advancing age, female sex, hypertension, hypercholesterolemia, and diabetes mellitus. Thyroid nodules are characterized as solitary, multiple, cystic, or solid lesions. Common thyroid neoplasms include thyroid cysts, follicular adenomas, and colloid nodules. Many thyroid nodules are asymptomatic and nonpalpable. The majority of these nodules are incidental findings on imaging studies. Other patients may present with a palpable anterior neck mass. Some patients may complain of neck pain. Palpation of the mass may reveal a well-circumscribed, mobile lesion that is nontender. Physical exam findings suspicious for malignancy include a fixed mass and surrounding lymphadenopathy. Vocal cord paralysis, which often presents as hoarseness or vocal fatigue, increases the suspicion for malignancy. There are four types of thyroid malignancies: papillary thyroid carcinoma (the most common type), follicular thyroid carcinoma, medullary thyroid carcinoma, and anaplastic thyroid carcinoma. Risk factors for developing thyroid cancer include a history of head and neck radiation, female sex, extremes of age, iodine deficiency, and certain inherited disorders. The initial workup for a thyroid nodule should include measurement of serum TSH and an ultrasound. A normal or high TSH can indicate a malignancy. Patients with a normal or high TSH should undergo an ultrasound. If suspicious features are found, the ultrasound should be followed by fine-needle aspiration. For patients with a low TSH, thyroid scintigraphy should be performed in place of an ultrasound to evaluate the functional status of the nodule. A low TSH indicates hyperthyroidism, and a hyperfunctioning thyroid nodule does not require fine needle aspiration. Ultrasound is helpful in detecting the size, shape, number, and makeup of the nodule. Sonographic features suspicious for malignancy include microcalcifications, irregular borders, hyperechoic regions, and increased vascularity. The gold standard diagnostic study for a thyroid nodule is fine-needle aspiration, which is performed with ultrasound guidance. Indications for fine-needle aspiration include nonpalpable thyroid nodules larger than 1 cm, palpable nodules smaller than 1.5 cm, nodules in proximity to blood vessels, cystic or mixed nodules, and lymphadenopathy. The results are described as one of the following: nondiagnostic, benign, atypia of undetermined significance, follicular neoplasm, suspicious for malignancy, or malignant. The risk of cancer increases with each of the aforementioned results. The risk of cancer nears 99% if the fine-needle aspiration is classified as malignant. Most thyroid nodules are benign and require only routine follow-up. If a fine-needle aspiration is performed, the results will determine the follow-up schedule. For benign lesions, yearly follow-ups are considered routine. If any subsequent ultrasounds reveal a suspicious feature, then fine-needle aspiration should be repeated. If the fine-needle aspiration returns results that are of undetermined significance or reveals a follicular neoplasm, a repeat final aspiration within 12 weeks is required. It is important to note that fine-needle aspiration cannot diagnose follicular cancer, which can only be diagnosed with complete removal of the thyroid nodule. Results that return as suspicious for malignancy or malignant should be referred for surgery. Often, these lesions represent papillary cancer, lymphoma, or metastatic cancer. The prognosis for thyroid malignancy varies based on the stage of the tumor at diagnosis, although the mortality rate is low. Papillary and follicular thyroid cancers have the best prognosis. Anaplastic thyroid cancer has the worst prognosis.
A 30-year-old woman presents with sudden-onset palpitations and forceful heartbeats. She reports an unintentional 25-pound weight loss over 2 weeks, despite increased appetite. On exam, she is tachycardic and hypertensive, and the thyroid gland is diffusely enlarged and nontender. Exophthalmos is also noted. Laboratory studies demonstrate elevated thyroxine, low serum TSH, and positive TSH receptor antibodies. Which of the following is the most likely diagnosis?
graves disease Hyperthyroidism is a condition that is characterized by the overproduction of the thyroid hormones (triiodothyronine and thyroxine), leading to a suppression of TSH. It is more prevalent in women than in men, with an average age of 20 to 40 years at onset. The most common cause of hyperthyroidism is Graves disease, which is an autoimmune disease that affects TSH receptors by stimulating or blocking antibodies to the thyrotropin receptor. Graves disease is associated with human leukocyte antigen markers and other autoimmune diseases. Other causes of hyperthyroidism include toxic multinodular goiter, subacute thyroiditis, pituitary tumor, pregnancy, ingestion of exogenous thyroid hormone, excessive dietary iodine intake, radiographic contrast, and amiodarone. Patients with Graves disease present with sudden onset of cardiac symptoms (tachycardia, palpitations, forceful heartbeat, atrial fibrillation, wide pulse pressure, and premature ventricular contractions), neurological symptoms (anxiety, fine tremor, insomnia, fatigue, irritability), skin symptoms (brittle hair, moist and warm skin, onycholysis), weight loss despite good food intake, menstrual irregularity, and heat intolerance. Some patients are asymptomatic. A physical exam reveals enlarged or nodular thyroid. Exophthalmos, upper eyelid retraction, pretibial myxedema (characterized by nonpitting edema with a waxy, orange-brown hue and a peau d'orange appearance on the legs), and lid lag with a downward gaze are physical findings that are specific for Graves disease. The initial screening tests for hyperthyroidism include serum TSH and T4 levels. A low TSH level and a high T4 level are diagnostic of hyperthyroidism. When T4 is normal and T3 is elevated, it indicates T3 toxicosis, which has a more favorable prognosis. Thyroid-stimulating immunoglobulin antibodies are most sensitive for Graves disease, although peroxidase and antithyroglobulin antibodies may be present but are less common. Graves disease can be differentiated from toxic multinodular goiter by the presence of peroxidase and thyroglobulin antibodies in the serum. Thyroid ultrasound can evaluate anatomical features of the thyroid gland but does not provide information about the functioning of the thyroid gland. Radioactive iodine uptake study evaluates the functioning of the thyroid gland and shows increased uptake of the radiotracer in Graves disease and toxic multinodular goiter. However, uptake is more diffuse and symmetrical in Graves disease, whereas it is patchy with pockets of concentrations (hot nodules) in toxic multinodular goiter. Patients presenting with acute cardiac symptoms associated with hyperthyroidism can be treated using beta-blockers (such as propranolol). Graves disease can be treated with the thiourea class of drugs (propylthiouracil and methimazole). Propylthiouracil is preferred during pregnancy and breastfeeding and is associated with several side-effects, including arthritis, lupus, aplastic anemia, hepatic necrosis, and thrombocytopenia. Methimazole is generally preferred over propylthiouracil for nonpregnant women due to lower risk of hepatic necrosis and dosing conveniences. However, it is associated with serum sickness, cholestatic jaundice, alopecia, nephrotic syndrome, and hypoglycemia. Refractory Graves disease can be treated by radioactive iodine ablation or thyroidectomy. Radioactive iodine ablation is contraindicated in pregnancy. Patients who have undergone treatment using radioactive iodine ablation or thyroidectomy will require lifelong thyroid hormone therapy and monitoring for parathyroid hormone and calcium levels.
A 28-year-old woman presents to the clinic complaining of fatigue, dry skin, generalized muscle pain, and inability to concentrate that has worsened over the past year. Upon physical exam, she has slowed speech and movement, dry skin, periorbital edema, and decreased deep tendon reflexes. A laboratory test shows an elevated thyroid-stimulating hormone level and a low free thyroxine level. Which of the following medications is first-line therapy for this condition?
levothyroxine
A 35-year-old woman presents to her primary care provider for her annual physical. She has no significant past medical history, however, she has a significant family medical history of pheochromocytoma and hyperparathyroidism on her father's side. On physical exam, she has a palpable, nontender nodule in the left lobe of her thyroid. She denies dysphagia or hoarseness. Ultrasound confirms the presence of a suspicious thyroid nodule. She is referred to a general surgeon. What type of thyroid cancer is most likely?
medullary
A 32-year-old woman who is 9 weeks pregnant presents to the clinic to discuss her routine annual exam labs. Over the last few months, she has noticed a decrease in her energy level and has experienced intermittent episodes of her "heart racing." Her vitals are as follows: weight 146 pounds, body mass index 24.6 kg/m2, O2 99% on room air, heart rate 90 bpm, and blood pressure 120/86 mm Hg. Her labs are all within normal limits with the exception of TSH at 0.12 µU/mL, total T4 at 15 µg/dL, and total T3 at 218 ng/dL. Which of the following therapies is most appropriate for this patient?
propylthiouracil The patient in the vignette has hyperthyroidism. Hyperthyroidism is a condition in which the thyroid gland overproduces thyroid hormones. The most common cause of hyperthyroidism is Graves disease, followed by toxic multinodular goiters and toxic adenomas. The patient may report episodes of tachycardia, palpitations, increase in anxiety, unintentional weight loss, heat intolerance, fatigue, fine tremors, or diarrhea. On physical exam, there may be a nodule or enlargement of the thyroid gland. If the patient has Graves disease, their eyes may be bulging anteriorly, which is known as exophthalmos. However, it is important to know that some patients with hyperthyroidism may not have any clinical findings on physical exam, therefore, it is important to make the diagnosis based on laboratory tests. For patients with hyperthyroidism, the TSH level would be low and the T3 and T4 levels would be elevated. Additional tests, such as a positive antithyrotropin receptor antibody and a positive thyroid-stimulating immunoglobulin, can help distinguish Graves disease from other types of hyperthyroidism. The various causes of hyperthyroidism can also be distinguished using a radioactive iodine uptake scan. It is important to note that a thyroid ultrasound can be obtained to evaluate anatomical features of the thyroid, however, the thyroid ultrasound will not give any information regarding the thyroid function and is therefore insufficient to aid in the diagnosis of hyperthyroidism. The initial treatment for hyperthyroidism is an antithyroid-modulating drug, such as methimazole or propylthiouracil. For patients who are pregnant, especially in their first trimester like the patient in the vignette, propylthiouracil is the preferred treatment.
A 35-year-old woman presents to her primary care physician for her annual physical exam. CBC, CMP, lipid panel, and TSH are drawn. Lab results reveal a serum calcium of 11 mg/dL that was confirmed by repeat CMP. What is the best next step in evaluating this patient?
serum parathyroid hormone Asymptomatic hypercalcemia detected by routine evaluation is the most common clinical presentation of primary hyperparathyroidism. The mean serum calcium concentration is typically elevated less than 1.0 mg/dL above the normal range. Increasingly, patients evaluated for low bone density or other conditions can have an elevated parathyroid hormone level in the absence of hypercalcemia or elevated ionized calcium levels. Classical presentations of hyperparathyroidism include bone disease, nephrolithiasis, weakness, fatigue, and neurobehavioral symptoms. Neurobehavioral symptoms can include lethargy, cognitive dysfunction, depressed mood, psychosis, and decreased social interaction. If an elevated serum calcium concentration is found on routine testing, confirmation by repeat lab draw is the first step. If an elevated level is found on repeat lab draw, the next step in evaluation is a serum parathyroid hormone. Elevated serum calcium and elevated serum parathyroid hormone are diagnostic for primary hyperparathyroidism. Patients with hypercalcemia and an upper limit of normal or slightly elevated parathyroid hormone should be evaluated for familial hypocalciuric hypercalcemia with a 24-hour urine calcium. Patients with symptomatic hyperparathyroidism should have parathyroidectomy, which cures the disease, increases bone mineral density, reduces fracture risk, and reduces risk of kidney stones. Surgery over observation is recommended for asymptomatic patients if they have a serum calcium concentration of 1.0 mg/dL or more above the upper limit of normal; bone density of hip, lumbar spine, or distal radius greater than 2.5 standard deviations below normal; previous asymptomatic vertebral fracture; glomerular filtration rate (GFR) less than 60 mL/min; 24-hour urine calcium greater than 400 mg/day; nephrolithiasis on imaging; and age less than 50 years. However, asymptomatic patients who do not meet the above criteria may choose surgery, as it is the only definitive treatment.
