Thyroid/Parathyroid Flashcards

Question

How does **Lugol's solution** work?

Answer 1

Excess iodine inhibits thyroid hormone **Wolff-Chaikoff Effect** Contraindicated in RA

Answer 2

suppress the hypothalamic-pituitary-thyroid axis

Answer 3

Used to control peripheral manifestations of sympathetic overactivity

Answer 4

1. **Total T4:** radioimmunoassay measures free and bound T4 2. **Free T4:** measures unbound T4, more specific for hypo- and hyperthyroidism 3. **TSH**: radioimmunoassay measures TSH, most sensitive test for primary hypo- and hyperthyroidism 4. **Total T3**: radioimmunoassay measures free and bound T3, useful for toxic nodules and toxic multinodular goiters (higher increase in T3 than T4) 5. **TRH Stimulation Test**: measures TSH after infusion of TRH, tests pituitary secretion of TSH and hypothalamic response 6. **Radioactive Iodide Uptake (RAIU**): measures the percentage of radiolabeled iodine taken up by the thyroid, assess metabolic status 7. **Calcitonin:** elevated in medullary thyroid carcinoma 8. **Resin T3 Uptake (RT3U):** measures the binding capacity of existing TBG, indirect measurement of TBG, an increased RT3U suggests a decreased total TBG (pregnancy or estrogen from oral contraceptives increases TBP and therefore increases total T4, however will have a normal euthyroid state (normal free T4)

Answer 5

You must do a hemithyroidectomy to examine architecture Could be adenoma or carcinoma Specifically, you are looking for **extracapsular spread, LVI or vascular invasion, or metastasis**

Answer 6

Medullary carcinoma

Answer 7

These are hypofunctioning nodules Have a **5-20% malingancy rate** Consider lobectomy and isthmusectomy

Answer 8

These are hyperfunctioning **4%** malignancy rate Maybe be observed

Answer 9

**Pathophysiology** typically arises from degenerated nodules, may result from cystic degeneration of malignancy **Symptoms** smooth, round mass **Diagnosis** FNA, ultrasound, CT **Treatment** may observe for regression, fine needle aspirate relieves pain and acquires cells for cytology, may consider lobectomy for recurrent cysts that are recalcitrant to drainage or bloody aspirates

Answer 10

* More common in **women** * Pathophysiology: iodine deficiency ➝ TSH hypersecretion ➝ stimulates chronic thyroid hyperplasia and involution ➝multinodularity **Types** 1. **Endemic Goiter:** iodine deficiency, extrinsic goitrogens (soybeans, lithium, iodides, etc.) 2. **Sporadic**: uncertain etiology **Symptoms** multiple nodules of varying size,may present with compressive symptoms (stridor, dysphagia) **Diagnosis** FNA of a prominent nodule, TFT to confirm euthyroid state (may be hypothyroid), consider radionuclear scanning to evaluate functional status **Treatment** ``` iodine replacement (reverses goiter), hormonal suppression (controversial), radioactive iodine therapy or surgical excision (subtotal thyroidectomy) may be considered for cosmesis, decompression, concern of malignancy, or toxicosis ```

Answer 11

**Pathophysiology** intrathoracic extension of thyroid gland (inferior extension is the path of least resistance) **Symptoms** dyspnea, stridor, dysphagia, choking, superior vena cava syndrome **Diagnosis** CT/MRI of neck and chest, radionuclear scanning **Treatment** surgical excision, typically accessed from collar incision although a sternotomy may be required

Answer 12

1. **Elevated Metabolic Rate**: weight loss, fatigue, sweating, heat intolerance 2. **Increased Sympathetic Activity:** palpitations, tachycardia, tremor 3. **Increased Protein Degradation**: weakness, fine hair 4. **Neurologic Effects**: increased deep tendon reflex, nervousness 5. **Reproductive Effects**: abnormal menstrual cycle, decreased libido

Answer 13

* Graves’ Disease * Multinodular Toxic Goiter * Subacute Thyroiditis * Exogenous from medications, iodine induced * Uninodular Toxic Goiter * Thyroid Cancer * Pituitary tumors

Answer 14

**Pathophysiology** thyroid receptor autoantibody (IgG) ➝ stimulates glandular hyperplasia via TSH receptor ➝ goiter and increased T3 and T4 secretion **Risks** radiation exposure, women (adolescence or 30-40), genetic disposition **Histopathology** hyperplasia, increased colloid material, papillary projections **Symptoms** diffuse goiter, hyperthyroid symptoms (see above), infiltrate dermopathy, **exophthalmos** (autoimmune ➝ extraocular muscle deposition), blindness from optic neuropathy, pre-tibial myxedema **Diagnosis** thyroid-stimulating autoantibodies; elevated T3, T4, RAIU, and thyroglobulins; decreased serum TSH; radioactive iodine scan reveals diffuse uptake

Answer 15

1. **Propylthiouracil and Methimazole** may be considered forsmall goiter and moderate disease 2. **Propanolol**: may be supplemented for severe symptoms 3. **Radioactive Iodine** (**131I**): indicated for more severe symptoms or failed medical therapy; there is risk of hypothyroidism and is contraindicated in pregnancy 4. **Subtotal Thyroidectomy**: indicated for failed medical therapy, pregnancy (especially in second trimester), noncompliance, suspicious nonfunctioning (“cold”) nodule, compressive symptoms

Answer 16

* **Reduced Metabolic Rate**: weight gain, cold intolerance, lethargy * **Decreased Sympathetic Activity:** bradycardia, constipation * **Decreased** Protein Degradation: weakness, fine hair, hoarseness * **Decreased** Neurologic Response: slowed deep tendon reflex, depression * **Myxedema**: nonpitting edema * **Creatinism**: hypothyroidism in children; mental retardation, impaired physical growth, macroglossia, protruberant abdomen * **Myxedema Coma**: severe hypothyroidism; hypothermia, hypoglycemia, hypoventilation, ileus, death; Rx: parenteral levothyroxine, corticosteroids

Answer 17

* Radiation Therapy * Chronic Thyroiditis * Idiopathic Atrophy * Hashimoto’s Thyroiditis * Surgical or Radioiodine Ablation Therapies * Secondary Hypothyr oidism (pituitary or hypothalamic dysfunction) * Iodine Deficiency * **Congenital Hypothyroidism:** from maternal iodine expectorants, anti-thyroid medications, and anti-thyroid antibodies

Answer 18

**Pathophysiology** viral (mumps, Coxsackivirus) ➝ decreased iodine uptake (unlike Grave’s) **Symptoms** painful enlarged thyroid, self limiting, malaise, associated upper respiratory infection **Diagnosis** clinical history, TFT (may be transient hyperthyroid) **Treatment** symptomatic therapy, observation

Answer 19

associated with lymphoma, neoplasms, other autoimmune disease **Pathophysiology** anti-thyroglobulin & anti-microsomal Ab ➝ anti-TSH receptor ➝ transient hyperthyroid then hypothyroidism **Risks** women, genetic susceptibility (HLA-DR3), Sjögren’s, DM, pernicious anemia **Histopathology** fibrosis, lymphocytic infiltration **Symptoms** slowly enlarging goiter, painless **Diagnosis** antimicrosomal antibodies, ESR, TFT (may have elevated, normal, or low serum levels of T4 and TSH), FNA only for prominent nodules suspicious of carcinoma or lymphoma that do not resolve with medical therapy) **Treatment** long term thyroxine therapy with TFT monitoring; surgical excision for compressive symptoms, suspicious nonfunctioning (“cold”) nodule, and pregnancy

Answer 20

Painless thyroiditis

Answer 21

* thyroid fibrosis of unknown origin, “rock hard” thyroid, produces local pressure and hypothyroidism; * hormone replacement, may consider surgical release at isthmus

Answer 22

* uncommon infection * Rx: systemic antibiotics, consider drainage for abscess formation

Answer 23

1. **Age:** males ≥41 years old, females ≥51 years old 2. **Metastasis**: presence of metastasis suggests malignancy 3. **Extent:** extrathyroidal, major capsular involvement 4. **Size**: nodule ≥5 cm 5. **Other**: radiation therapy, autoimmune thyroiditis, more common in women (children and males have a higher risk of malignancy if presents with a thyroid nodule) **Staging**: I: thyroid only; II: nonfixed cervical node; III: fixed cervical node; IV: metastasis

Answer 24

* 70% of solitary nodules * **follicular adenomas** are the most common * papillary adenomas are exceedingly rare

Answer 25

* most common * more common in young females **Risks** radiation exposure, **Gardner’s syndrome** 30% palpable regional nodes (70% occult nodes) **Diagnosis** FNA **Histopathology** papillary and follicular structures, **psammoma bodies** (calcific), intranuclear vacuoles (**“Orphan Annie” eyes**), **multicentric** **Prognosis** **95%** 5-year survival; poor prognostic indicators include tumors \>1.5 cm or extracapsular spread (cervical metastases have increased cervical recurrence rates without affecting survival) **Treatment** 1. Total or near total thyroidectomy (multicentric) 2. Lobectomy and isthmusectomy (hemithyroidectomy) with radioactive iodine (I131) may be considered if \<1.5 cm or in younger patients 3. Modified neck dissection (MND) for palpable nodes only (elective neck dissection [END] has not been shown to improve survival) 4. Thyroid suppression therapy

Answer 26

* more common in the elderly and in females * 50% **_hematogenous_** spread with distant metastasis (lymphatic spread rare) **Diagnosis** **requires open biopsy** (unable to distinguish adenoma from carcinoma from FNA) **Histopathology** **unifocal**; extracapsular spread, invasion of lymphatics or vasculature, or metastasis required for diagnosis **Prognosis** **70–85%** 5-year survival (20% with distant metastasis), worse prognosis for angioinvasion, extracapsular spread **Treatment** 1. Lobectomy and isthmusectomy (hemithyroidectomy) for low risk groups (may consider intraoperative frozen section with completion total thyroidectomy (or subtotal) for carcinoma) 2. Subtotal or total thyroidectomy with radioactive iodine (I131) for high-risk groups (angioinvasion, extracapsular spread) 3. Lateral neck dissection for clinical nodes thyroid suppression therapy

Answer 27

* variation of follicular carcinoma (Hürthle cells predominate) * difficult to distinguish adenoma from carcinoma (assume malignancy) **Histopathology** Hürthle cells (large granular eosinophilic cells, trabecular pattern) **Treatment** same as follicular carcinoma

Answer 28

**Pathophysiology** derived from parafollicular or **C-cells** (produce calcitonin) **Types** 1. **Familial**: **20**%, Multiple Endocrine Neoplasia IIA/B, multicentric, **bilateral** 2. **Sporadic**: **80**%, unifocal, unilateral, worse prognosis, 50–60% lymph node involvement (late vascular involvement), approximately 8% distant metastasis ``` secretory granules of malignant C-cells release calcitonin and also secrete **gastrin**, adrenocorticotropin hormone (**ACTH**), **substance P**, carcinoembryonic antigen (**CEA**), and others ``` Prognosis 50–80% survival; worse prognosis if unilateral, sporadic type, younger patient, or with metastasis Diagnosis FNA or biopsy, elevated serum calcitonin, elevated CEA, presence of **Ret-3 oncogene** **Histopathology** small round cells, amyloid stroma, may have calcification and fibrotic strands **Treatment** 1. Patient and family should be screened for MEN syndrome), examine for mucosal neuromas, marfanoid habitus, serum calcium levels, urine catecholamines and metabolites (vanillylmandelic acid, metanephrine) 2. Total thyroidectomy with elective or modified neck dissection and medical thyroid suppression therapy 3. Screen with calcitonin levels to monitor for recurrence

Answer 29

Parafollicular cells do not take up I131

Answer 30

• most commonly seen in the elderly **Pathophysiology** may be from transformation of a well-differentiated carcinoma (may find coexistent follicular or papillary carcinoma) **uniformly fatal** (5-year survival), often found with metastatic disease **Histopathology** giant and spindle cells variation, undifferentiated **“bizarre cells”** **Treatment** no adequate therapy, tracheotomy (protect airway), consider radiation and chemotherapy, surgical resection may be considered (controversial)

Answer 31

• associated with **chronic lymphocytic thyroiditis** and **Hashimoto’s thyroiditis** **Diagnosis** difficult to distinguish lymphoma from chronic lymphocytic thyroiditis by FNA alone, therefore a conformational open biopsy is required along with lymphoma staging work-up **Treatment** Radiotherapy to neck and superior mediastinum, surgical excision considered if tumor is confined to the thyroid

Answer 32

Used in Graves disease, to decrease vascularity of gland and therefore decrease blood loss (in theory)

Answer 33

1. Cancer 2. Compression (SOA, dysphagia) 3. Cosmesis 4. Failed medical management for Graves or hyperthyroidism 5. Pregnancy in Graves disease or Hashimoto's thyroiditis

Answer 34

* **Hematoma** * **VF paralysis** - RLN or SLN injury (SLN more common), avoid ligation of inferior thyroid artery * **Transient or permanent hypocalcemia** - may reimplant parathyroid into SCM. Prevent by avoiding ligation of inferior thyroid artery * **Thoracic duct injury** - rare, leads to chyle leak

Answer 35

Less calcium means lower threshold of depolarization **CAT**S **go numb** **_C_**onvulsions, **_A_**rrhythmias, **_T_**etany and numbness/parasthesias in hands, feet, around mouth and lips. **Chvostek's sign** - tapping of the inferior portion of the zygoma will produce facial spasms **Trousseau sign** - eliciting carpal spasm by inflating the blood pressure cuff and maintaining the cuff pressure above systolic Intermittent **QT prolongation leading to Torsades de Pointes** **Treatment** Give 2 amps of IV Calcium Gluconate

Answer 36

**Etiology** surgery, trauma, childbirth, infection * _50%_ mortality **Symptoms** fever, profuse sweating, tachycardia, nausea, abdominal pain, tremors, restless, psychosis, coma, stupor **Diagnosis** clinical history and exam **Treatment** 1. Immediate administration of inorganic **iodine**, **propylthiouracil**, **propanolol**, and **corticosteroids** 2. Supportive measures (glucose-containing IV fluids, cooling blanket, supplemental oxygen, pyrogens) 3. Intensive care admission (cardiac monitoring)

Answer 37

* **Elevated serum PTH** * **Benign Adenoma**: _most common_, single adenomatous gland * **Parathyroid Hyperplasia**: associated with _MEN I & IIA_ * **Familial hypocalciuric hypercalcemia** (autosomal dominant, increased renal calcium absorption), familial hyperparathyroidism * **Carcinoma of the Parathyroid Gland:** rare tumor, suspect with a palpable, gray mass, vocal fold paralysis, or severe hypercalcemia; **Rx**: en bloc resection including thyroid lobectomy, monitor for recurrence with serial serum calcium levels * Must differentiate hyperparathyroidism from other causes of hypercalcemia

Answer 38

**CHIMPANZEES** * **C**alcium (exogenous) * **H**yperparathyroidism * **I**mmobility * **M**etastasis to bone * **P**aget's disease * **A**ddison's disease * **N**eoplasms (prostate, lung, colon, breast) * **Z**ollinger-Ellison syndrome (hypergastrinemia) * **E**xcess: vit A or D, thiazides, lithium, estrogens, milk-alkali syndrome * **E**ndocrine disorders: FHH, hyperthyroidism, pheochromocyoma * **S**arcoidosis and Tuberculosis

Answer 39

* Compensatory parathyroid hyperplasia secondary to malfunction of other organ system * decreased _1 hydroxylase in the kidney_ * patients are **hypocalcemic** **Causes** * **chronic renal disease**, osteogenesis imperfecta, Paget’s disease, multiple myeloma, bone metastasis

Answer 40

* Autonomous or irrepressible PTH production (parathyroid hyperplasia from secondary parathyroidism, persistent hyperfunction despite correction) * May have normal or low calcium

Answer 41

* _Contributing Factors_: family history of **MEN** disorders, radiation exposure * “Stones, bones, groans:” nephrolithiasis, osteitis fibrosa cystica, cholelithiasis * _Renal:_ polyuria, nephrolithiasis, nephrocalcinosis * _Gastrointestinal_: constipation, dyspepsia, pancreatitis * _Musculoskeletal_: muscle weakness, bone and joint pain (osteitis fibrosa cystica, calcific tendonitis) * _Central Nervous System_: slow mentation, fatigue, depression, poor memory, psychosis * _Cardiovascular_: heartblock, hypertension

Answer 42

* **_Serum Electrolytes:_** ionized calcium (should be elevated at 3 different times), **magnesium (usually low),** chloride (usually elevated from PTH induced bicarburia), and phosphate (usually low) * **_PTH levels_**: immunoradiometric assay * **_Plain Films_**: brown tumors (osteitis fibrosis cystica), loss of lamina, resorption of terminal phalanges, soft-tissue calcification, chest x-ray (granulomatous diseases or metastasis), abdominal film (renal calculi) * **_Others_**: alkaline phosphatase (suggests bone disease), BUN/creatinine (renal function), urine calcium (elevated in primary hyperparathyroidism, low levels with familial hypocalciuric hypercalcemia), TFT, ACE levels (sarcoidosis), serum prolactin and gastrin and urine catecholamines and metabolites (evaluate for MEN syndromes) * Think “**_CHIMPANZEES_**” for other causes of hypercalcemia

Answer 43

* **Thallium-Technetium Subtraction:** thallium uptake by thyroid and parathyroid, technetium uptake by thyroid gland only, parathyroid glands identified by computer subtraction; up to 90% accurate (less accurate for multiple gland hyperplasia, associated thyroid disease, or small glands) * **High-resolution Ultrasound:** can not locate mediastinal, retrotracheal, retroesophageal, or small nodes * **Selective Venous Catheterization** for PTH: reserved after exploration has failed * **CT/MRI**: poor resolution, MRI more useful in identification of glands

Answer 44

**NO** **Sulfur colloid** is a component of this radioactive material

Answer 45

* **Surgery** is the only definitive cure, avoids long-term complications of nephrocalcinosis and bone demineralizations * **Parathyroidectomy** is indicated for symptomatic (bone pain, pathological fractures, ectopic calcifications, intractable itching, etc) or persistently elevated serum calcium * **_Surgical Theory_**: must first remove pathologic gland (adenoma), hyperplasia versus adenoma can not be distinguished grossly, therefore, must identify one “normal” gland to evaluate hyperplasia, if other gland is also hyperplastic then assume parathyroid hyperplasia and perform a subtotal (31/2 glands) or total parathyroidectomy with autotransplantation, if gland is normal may either assume adenoma and terminate case or further biopsy other contralateral glands (controversial) * **Autotransplantation** requires _20 mg_ into muscle bed (usually to forearm) * Pregnant women should undergo surgery during **second trimester** to avoid miscarriage

Answer 46

* **Persistent Hypercalcemia**: most commonly from missed adenoma (the most commonly missed location is the posterior mediastinum), also from supernumerary gland, second adenoma, failed recognition of parathyroid hyperplasia, incorrect diagnosis, and residual adenoma * **Postoperative Hypocalcemia and Hypomagnesmia**: usually temporary until replacement of low bone calcium stores (increased risk with elevated alkaline phosphatase) * **Nerve Injury and Hematomas**

Answer 47

* **Saline Diuresis**: restores extracellular fluid volume and promotes calcium excretion, loop diuretics can also be given (thiazides impair calcium excretion) * **Biphosphonates**: inhibit bone resorption, calcium serum levels reduce over several days * **Plicamycin**: inhibits bone resorption; toxic side effects include thrombocytopenia, hepatic dysfunction, and renal failure, therefore used only for malignant hypercalcemia * **Calcitonin**: rapid onset (serum calcium falls within hours) * **Glucocorticoids**: inhibit calcium intestinal absorption, may be effective for hypercalcemia secondary to malignancy * **Gallium Nitrate**: inhibits bone resorption, used for parathyroid carcinoma * **Hemodialysis**: indicated for life-threatening conditions

Answer 48

* A pyramidal extension of the thyroid gland, present at the most **posterior** side of each lobe * The structure is important in thyroid surgery as it is closely related to the **recurrent laryngeal nerve, the inferior thyroid artery, Berry's ligament and the parathyroid glands**. * The structure is subject to an important amount of anatomic variation

Answer 49

**Hyperparathyroidism** (adenoma) In hospitalized patients, think malignancy!

Answer 50

Postop hypocalcemia can occur following parathyroidectomy. The chronic stimulation of the bone with PTH results in the skeletal depletion of calcium The normalization of PTH causes the bone **reuptake of calcium**, with a resultant fall in serum calcium

Answer 51

* Rare disorder * Surgical exploration should occur in 2nd trimester * Should perform **total parathyroidectomy with autotransplant** * After birth, neonates serum calcium level can drop quickly * **7-10 days** for babys parathyroids to secrete PTH

Answer 52

* arises from the brachiocephalic trunk and ascends in front of the trachea to the lower part of the thyroid gland, which it supplies. * It is only present in approximately 3-10% of the population

Answer 53

Superior parathyroids are posterior to the RLN Inferior parathyroids are anterior to the RLN

Answer 54

The caudal end of the cricopharyngeus muscle (cricothyroid membrane)