Endocrinology
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93 terms
Terms | Definitions |
|---|---|
 embryologic origin thyroid | endoderm between 1st and 2nd branchial arch on floor of pharynx (foramen cecum) invaginates 4th week and descends into mesenchymal tissue |
| embryologic pathology | athyreosis (rare), ectopic thyroid, thyroglossal duct cyst |
| inferior and superior parathyroid arteries usually arise from this | inferior thyroid artery (superior parathyroid artery may arise from superior thyroid artery) |
| blood supply to thyroid isthmus (and where it comes from) | aortic arch or innominate artery -> thyroid ima artery |
| lymphatic drainage of isthmus and medial lateral lobes " " of inferior lateral lobes | delphian (prelaryngeal) and digastric pretracheal and cervical nodes |
| SLN internal branch parallels __ and then goes through ___. may form ___ __ ___ | superior thyroid artery thyrohyoid membrane loop of Galen (after anastomosing with sensory branch of RLN) |
| SLN external branch innervates | cricothyroid muscle |
| RLN relationship to inferior thyroid artery | near middle 1/3 of gland it crosses posteriorly or superficially to the inferior thyroid artery |
| describe thyroid hormone synthesis | thyroglobulin is iodinated to form MIT, DIT (mono/di iodotyrosine) which link to form triiodothyronine T3 or thyroxine T4 |
| this is 90% of thyroid output | T4 |
| what is thyroid hormone transported on (protein and %) | TBG thyroxine binding globulin 75% thyroxine binding pre albumin TBPA 15% albumin 5% |
| these organs convert T4 to T3 and rT3 via 5'monodeiodinase | liver, kidneys, muscle |
| T3 is __ x more active than T4 and binds with higher affinity to TBG | 4 |
| propylthiouracil and methimazole belong to this class | thioamides |
| mechanism of thioamides | blocks conversion of T4 and oxidation and organification of iodine |
| Wolf-Chaikoff Effect | excess iodine inhibitis thyroid hormone synthesis |
| this test is more specific for hypo/hyper thyroidism | free T4 |
| this test is most sensitive for hypo/hyperthyroidism | TSH |
| what does RT3U (resin T3 uptake) measure | binding capacity of existing TBG, increased RT3U suggests decreased total TBG |
| TBG, total T4, RT3U, free T4 in normal patients | normal, normal, normal, normal |
| TBG, total T4, RT3U, free T4 in pregnant patients | increased, increased, decreased, normal |
| TBG, total T4, RT3U, free T4 in liver/renal disease | decreased, decreased, increased, normal |
| TBG, total T4, RT3U, free T4 in hyperthyroidism | normal, increased, increased, increased |
| TBG, total T4, RT3U, free T4 in hypothyroidism | normal, decreased, decreased, decreased |
| false negative rate of FNA | 1-10% |
| this FNA finding suggests nodular or adenomatous goiter | uniform follicular epithelium and abundant colloid |
| these 2 types of finding may be benign or carcinoma, requires hemithyroidectomy to examine architecture | follicular cells, hurthle cells |
| hurthle cells associated with this condition | Hashimoto's thyroiditis |
| 99mTc pertechnetate is trapped by these cells | follicular cells |
| this tracer used to evaluate for metastasis and also for ablation for hyperthyroidism and residual disease | 131Iodine |
| this tracer is expensive, must be delivered daily, testing requires 2 visits at 4 and 24 hrs (shorter half life) | 124 Iodine |
| malignancy rate for hypofunctioning/cold nodule | 5-20% |
| malignancy rate for hyperfunctioning or autonomous functioning "hot" nodule | 4% |
| which staging system to use for papillary/follicular/medually thyroid cancer depends on this criteria | < or > 45yo |
| papillary/follicular/medually thyroid cancer staging <45yo | stage I - any T, N, M0 stage II - any T, N, M1 |
| T staging for papillary/follicular/medually thyroid cancer | T1 - <2cm T2 - >2cm, <4cm T3 - >4cm, minimal extrathyroidal extension T4 4a - beyond thyroid capsule 4b - prevertebral fascia, carotid, mediastinal vessels |
| N staging for papillary/follicular/medually thyroid cancer | N0 - no nodes N1a - delphian or pre/paratracheal LNs N1b - cervical, superior mediastinal nodes |
| Staging for papillary/follicular/medually thyroid cancer >45yo | I - T1, N0, M0 II - T1-2, N0, M0 III - T1-3, N0-1a, M0 IVa - T1-4a, N0-1b, M0 IVb - T1-4b, N0-1b, M0 IVc - T1-4b, N0-1b, M1 |
| T staging for anaplastic thyroid cancer | T4a - intrathyroidal/surgically resectable T4b - extrathyroidal/surgically unresectable |
| Staging for anaplastic thyroid cancer | IVa - T4a, any N, M0 IVb - T4b, any N, M0 IVc - T4b, any N, M1 |
| thyroid neoplasia - high risk criteria | AMES age (>41yo men, >51yo women) metastases extrathyroidal, major capsular involvement size (>5cm) |
| single most significant overall indicator of poor prognosis | distant mets, especially to bone |
| most common type of benign adenoma | follicular adenoma |
| most common thyroid cancer and % | papillary, 70-80% |
| this syndrome is a risk factor for papillary thyroid cancer (PTC) | Gardner's syndrome |
| histopath for PTC | psamomma bodies (calcific) Orphan Annie eyes (intranuclear vacuoles) multicentric unencapsulated neoplastic cells (ground glass appearance) with fibrovascular stalks |
| improvement in survival with elective neck dissection in PTC? | no |
| neck management in PTC? | modified neck dissection for palpable nodes only |
| may consider lobectomy and isthmusectomy in these patients with PTC | <1cm in younger patients, controversial |
| follow up in this amount of time for RAI after thyroidectomy for PTC | 6 weeks |
| second most common thyroid cancer and % | follicular carcinoma (FTC), 10% |
| 20-50% of FTC have this type of spread | hematogenous spread with distant metastasis (lymphatic spread rare) |
| histopath for FTC | unifocal malignancy differentiated by presence of extracapsular spread, invasion of lymphatics or vasculartor or metastasis solid, trabecular, or follicular growth patterns |
| 5 year survival for PTC, FTC and FTC with distant mets, and hurthle cell tumor (oncocytic carcinoma) | 95% for PTC 70-85% for FTC (20% with distant mets) 50% for hurthle cell (oncocytic carcinoma) |
| do Hurthle cell tumors take up radioactive iodine? | no, less sensitive to thyroid suppression and diagnostic and therapeutic radioactive iodine therapy |
| 2 types of medullary thyroid cancer (MTC), their prevalence (%), centricity, laterality, which one is worse prognosis | familial (20-25%), multifocal, bilateral sporadic (70-75%), unifocal, unilateral, worse prognosis |
| medullary thyroid cancer derived from this cell type | neuroendocrine parafollicular or C-cells (produce calcitonin) |
| mutation and chromosome for MTC | Ret-3 oncogene, chromosome 10 |
| management for MTC | total thyroidectomy, elective modified neck dissection, medical thyroid suppression therapy |
| consider this in childhood with positive germline RET mutations | prophylactic thyroidectomy |
| prognosis for anaplastic carcinoma including median survival | uniformly fatal (2-6 month median) |
| histopath of anaplastic carcinoma | bizarre cells giant and spindle cell variation with high mitotic activity, large areas of necrosis, significant infiltration |
| primary lymphomas of the thyroid are most commonly this type of tumor | non Hodgkin B cell tumors |
| primary lymphoma of the thyroid associated with these conditions | chronic lymphocytic thyroiditis, Hashimoto's thyoiditis |
| MEN I, II (2a), III (2b) | MEN I (Werner's) - PPP pituitary adenoma, pancreatic tumors, parathyroid hyperplasia MEN II (Sipple's) - MPP medullary thyroid cancer, pheochromocytoma, parathyroid hyperplasia MEN III (2b) - MPMM medullary thyroid cancer, pheochromocytoma, mucosal neuromas, marfanoid habitus |
| may consider prior to thyroidectomy to reduce vascularity of gland | Lugol's solution (potassium iodine) |
| indications for thyroidectomy | suspicion of malignancy mediastinal extension compression symptoms (airway compromise, dysphagia) cosmesis failed medical management Grave's or hyperthyroidism pregnancy in Grave's or Hashimoto's thyroiditis documented metastasis from thyroid carcinoma |
| Rx for respiratory distress from postop hematoma | immediately remove sutures and open wound |
| mortality rate from thyroid storm | 20-50% |
| Rx thyroid storm | inorganic iodine PTU (propylthiouracil) propranolol corticosteroids supportive measures (glucose containing IVF, cooling blanket, O2, antipyretics), ICU admission for cardiac monitoring |
| another name for toxic nodular goiter | Plummer's disease |
| PPx Grave's disease | thyroid stimulating immunoglobulins (TSIs) stimulate glandular hyperplasia via TSH receptor -> goiter and increased T3, T4 secretion |
| risks for graves | radiation exposure, women (adolesence or 30-40yo), genetic disposition |
| SSx grave's | exophthalmos (autoimmune - T cell - retrobulbar fibroblast interaction which has Ag similar to TSH receptor, secrete GAGs, collagen deposition. previously thought to be extraocular muscle deposition) diffuse goiter, hyperthyroid symptoms, infiltrative dermopathy |
| these types of thyroiditis can be painful | subacute granulomatous thyroiditis (de Quervain's) acute suppurative |
| another name for Hashimoto's thyoiditis | chronic autoimmune |
| PPx Hashimoto's | antithyroglobulin and antimicrosomal antibodies -> TSH receptor -> transient hyper, then hypothyoidism |
| Dx Hashimoto's | antithyroid peroxidase (antimicrosomal ABs, anti-TPO, and anti-Tg) ESR, TFT, FNA for suspicious nodules |
| thyroid fibrosis of unknown origin, rock hard thyroid, local pressure, hypothyroidism | Riedel's thyroiditis |
| these parthyroids have a more variable location | inferior (generally 1-2cm from entrance of inferior thyroid artery to lower thyroid pole) superior paras - 1cm above intersection RLN with inferior thyroid artery |
| parathyroid embryology | third dorsal branchial pouch ->inferior paras and thymus fourth dorsal branchial pouch -> superior paras and C-cells of thyroid |
| embryologic pathology of parathyroids | supernumeray parathyroids aberrant parathyroids (most commonly at anterior superior mediastinum) |
| action of parathyroid hormone (PTH) | increases serum calcium, decreases phosphate by stimulating osteoclastic resorption from bone, increasing Ca absorption in kidney, activating 25-hydroxyvitamin D to 1,25 dihydroxyvitamin D, increasing phosphate excretion |
| causes of hypercalcemia | CHIMPANZEES Calcium (exogenous) Hyperparathyroidism Immobility Metastases to bone Paget's disease Addison's disease Neoplasia (solid tumors prostate, lung, colon, breast) Zollinger Ellison (hypergastrinemia) Endocrine (familial hypocalciuric hypercalcemia, hyperthyroidism, pheochromocytoma) Exogenous (excess vit A, D, thiazides, lithium, estrogens, milk-alkali syndrome) Sarcoidosis (also other granulomatous disease TB, berylliosis) |
| SSx hypercalcemia/hyperparathyroidism | stones, bones, psychiatric overtones nephrolithiasis, cholelithiasis osteitis fibrosa cystica confusion |
| medical management hypercalcemia | saline diuresis bisphosphonates plicamycin calcitonin glucocorticoids gallium hemodialysis |
| most common cause of secondary hyperparthyroidism | chronic renal disease |
| how does thallium technetium subtraction scan work? sensitivity? | thallium taken up by thyroid + paras technetium taken up by thyroid only 90% |
| indications for parathyroidectomy | symptomatic hyperaparathyroidism (bone pain, pathologic fractures, ectopic calcifications, intractable itching) persistently elevated serum calcium |
| radioguided parathyroidectomy - how it works | tracer injected 1.5-2 hrs prior to surgery, gamma probe to identify abnormal gland |
| SSx hypoparathyroidism and hypocalcemia | tetany or neuromuscular excitability Chvostek's sign Trousseau's sign |
| DiGeorge embryology | congenital abnormality of third and fourth branchial pouches, agenesis of parathyroid glands, may have athymia |
| pseudohypoparathyroidism etiology | end organ resistance to effects of PTH |
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