Endo Flashcards
Percentage of T3 derived from conversion of T4
80%
Major thyroid hormone-binding protein
Thyronine-binding globulin (TBG)
% of T4 and T3 are bound
Greater than 99.5%
Major cause of decreased T3 concentration in patients with a critical illness
Impaired peripheral conversion of T4 to T3 secondary to inhibition of deiodination process
Embryonic origin of thyroid gland
Median downgrowth of 1st and 2nd pharyngeal pouches in the area of foramen cecum
Embryonic origin of parafollicular cells
Ultimobranchial bodies of 4th and 5th branchial pouches
Neuroendocrine cell lineage
Genetic mutation in medullary thyroid cancer
RET proto-oncogene
Electrolyte ratio pathognomonic for hyperparathyroidism
Serum chloride to phosphate ration >30
Hemodynamics of thyroid storm
Tachycardia
Increased CO
Decreased systemic vascular resistance (SVR)
What artery do all parathyroids typically receive their blood supply from?
Inferior thyroid
Oncogene of hyperparathyroid
Prad oncogene
Bone finding pathognomonic for hyperparathyroidism
Osteitis fibrosa cystica
Lab findings in hyperthyroidism
Hypercalcemia
Hypokalemia
Hyperglycemia
Hypocholesterolemia
Microcytic anemia
Lymphocytosis
Granulocytopenia
Hyperbilirubinemia
Increase alkaline phosphatase
Initial tx for thyroid storm
IV fluids
Hypothermia
Acetaminophen
Propranolol
PTU
Iodine
Single test would allow for differentiation of thyrotoxicosis from acute destruction viral thyroiditis
Radioactive iodine uptake (RAIU) test
What inhibits the release of TSH
Elevated circulating levels of T3, T4 and somatostatin
45yo
2yr hx of Diffuse, tender thyroid enlargement
Lethargy
20pound weight gain
Dx?
Hashimoto’s thyroiditis
Vebous drainage of thyroid gland
Superior and middle thyroid vein – Internal Jugular Vein
Inferior thyroid vein – Innominate vein
MC location of recurrent laryngeal nerve
Tracheoesophageal groove
Result of bilateral injury to Superior laryngeal nerve
Swallowing disorders
Single most important test in the diagnostic work up of patients with solitary thyroid nodule
FNA
Which thyroid malignancy does radiation increases the incidence
Papillary cell CA
This is a variant of follicular cell ca
SIZE is the only predictor of malignancy
Associated with history of Hashimoto’s thyroiditis
Hurthle cell CA
5cm thyroid nodule
FNA - fluid, nodule disappeared, cytology benign
Next step?
Total thyroid lobectomy with isthmusectomy
- increased chance of malignancy in large cysts (>3cm)
No risk factor
(+) thyroid jodule
FNA is non diagnostic (follicular cells)
Tx of choice?
Thyroid lobectomy with isthmusectomy
If follicular CA, secondary sx for completion total thyroidectomy w postop I-131 is indicated
Factor best correlates w presence of LN metastasis in papillary CA
Age
Tx of choice for patients with papilary thyroid ca without clinical evidence of LN metastasis
Total thyroidectomy
Pt with very highCalcium
Palpable roch hard neck mass
Dx?
Parathyroid carcinoma
Tx
Wide excision with en block resection of adjacent thyroid tissue
Neuroendocrine cell etiology
Can occur throughout GI tract or bronchi
Flushing, diarrhea, R sided heart failure most commonly occurs with metastatic disease and mid-gut tumors
Carcinod tumor
Tx: Octreotide
Isolated mets can be resected
Follicular carcinoma metastases occur primarily by?
Hematogenoys dissemination to lungs, bones and other peripheral tissues
Confirmation of follicular thyroid CA
Indentification of Vascular or Capsular invasion by tumor from histologic section
Surgical tx of medullay thyroid CA
Total thyroidectomy w Central node dissection, lateral cervical LN samplinv of palpable nodes and a modified radical neck dissection, if positive
Germline defect in what gene responsible for Multiple Endocrine Neoplasia (MEN2a and 2b) and Familiar Medullary Thyroid CA (FMTC)
RET Proto-oncogene
- should undergo prophylactic thyroidectomy before 10yo
Histo caharacteristic of Medullary thyroid CA (MTC)
Congo red dye (+)
Apple green birefringence consistent with amyloid
Immunihistochemistry (+) for cytokeratins, CEA and Calcitonin
PARAFOLLICULAR C CELLS are the precursor to tumor cells
(+) Medullary thyroid CA
High urinary Vanillylmandelic acid (VMA)
Enlrged left adrenal gland
Management?
Alpha and beta blockers
Then resection of left adrenal gland
–should be performed before thyroid sx
Embryological origin of parathyroid gland
Inferior parathyroid - 3rd pharygeal pouch
Superior parathyroid - 4th pharyngeal pouch
Etiologies of hypercalcemia
Hyperparathyroidism
Paraneoplastic syndrome
Metastatic CA
Bone metastasis
Milk-alkali syndrome
Sarcoidosis
Effect of PTH on intestinal absorption of calcium
PTH stimulates vit D hydroxylation in the kidney and increases intestinal absorption of calcium
Calcitonin is produced in?
Parafollicular cells (C cells) of thyroid
Serum Calcium of 13 mg/dL
Serum PTH 400 mEq/mL
Dx?
Prinary hyperparathyroidism
Serum Calcium of 8.5 mg/dL
Serum PTH 400 mEq/mL
Serum creatinine 5.6mg/dL
Dx?
Secondary hyperparathyroidism
Appropriate management if thr 4th Parathyroid hormone cannot be located by intraoperative utz
Terminate the operation for localization studies
Problem if injured external branch of superior laryngeal nerve
Loss of High-pitched tone
Components of MEN 1 syndrome
Parathyroid hyperplasia (90%)
Islet cell Neoplasms (30-80%)
Pituitary tumors (15-50%)
Tx of choice pt w hyperparathyroidism associated MEN 1 or MEN 2
Also secondary hyperparathyroidism
Subtotal (3 ½ gland) parathyroidectomy or total parathyroiderctomy w autotransplantation in the FOREARM
1st line therapy for patients with marked hypercalcemia and/or severe symptoms
IV hydration followed by furosemide
Idication of calcium supplement after thyroid or parathyroid sx
Circumoral paresthesia, anxiety, positive Chvostek’s or Trousseau’s sign, tetany, ECG changes or serum calcium less than 7.1 mL/dL
In a nonacute setting, what is the max useful amount of calcium supplementation
2g calcium/d
Appropriate Calcium suppplementation if max amount of calciun has already been given and patient still hypocalcemic
Calcitriol or other vit D preparations
Medullary thyroid carcinoma
Pheochromocytoma
Mucosal neuromas
Ganglioneuromas
MARFANOID habitus
Dx?
MEN 2b
Zone of adrenal gland spared in autoimmune adrenal disease
Medulla
Secretion of which adrenal hormone NOT impaired by secondary adrenal insufficiency
Aldosterone
MC cause of chronic primary adrenal insufficiency (Addison’s disease)
Autoimmune disease
MC cause of acute secondary adrenal insufficiency
Steroid medication withdrawal
Sheehan’s sybdrome (postpartum Pituitary necrosis)
Bleeding into a pituitary macroadenoma
Head trauma
Posterior pituitary secrete?
ADH and Oxytocin
Anterior pituitary secrete?
Growth hormone (GH)
Adrenal corticotropin hormone (ACTH)
TSH
LH
FSH
Prolactin
Therapy should be istituted to obtaininv the results of ACTH stimulation test in a critically ill patient
Empiric stress dose of DEXAMETHASONE
Basis of insulin-induced hypoglycemia test for patients with secondary adrenal insufficiency
Hypoglycemia induced by 0.1 unit of insulin/kg stimulates the entire hypothalamus-hypophyseal-adrenal axis (HPA) and the sympathetic nervous system
Plasma cortisol level should exceed 20g/dL
Decreased SVR
Hypotension with high CO
Normal filling pressure
Hypoglycemia
Dx?
Hemodynamic pattern of patient with ADRENAL INSUFFICIENCY
Daignostic test best predictor of adrenal adequacy in patients previously receiving steeoids, who are scheduled for surgery
Peak corrisol level after administration of corticotropin
45yo male
Hypotension and lethargy
Henoglobin 12g/dL
Blood glucose 34mg/dL 24 hrs after colectomy
Hx renal transplant 3 years ago
Dx?
Addisonian crisis
What inhibits GH secretion
Somatostatin
Where aldosterone exert its primary effect
Distal tubules and collecting Ducts of the kidney
Effect of aldosterone in kidney
Increases absorption of Sodium from urine in exchange for Potassium, aiding in water retention and restoring intravascular volume
Catecholamines in stress
Increase
Glycogenolysis
Gluconeogenesis
Lipolysis
Ketogenesis
Inhibit insulin use in peripheral tissue
Function of angiotensin II
VasoCONSTRICT
Cardiac stimulation
Stimulation of ADH, aldoaterone and thirst
Stimuli causes release of ADH (vasopressin)
Plasma osmolality greater than 285 mOsm/L
Decrease circulating blood volume, catecholamines, renin-angiotensin system and opiates
Inhibits release of LH in male adult
Androgens synthesized by testes
Function if FSH in adult female
Stimulates maturation of the Graafian follicle and production of estradiol
Limits secretion of ACTH and corticotropin-releasing factor (CRF)
Circulating levels of ACTH
GH released in bursts when?
3-4 hrs after meals and during stage III and IV sleep
Inhibits release of Prolactin
Dopamine
Main physiological stimulus of prolactin release
Suckling of breast
Drug interferes with release of dopamine into pituitary portal circulation and enhances prolactin secretion
Metaclopramide
Haloperidol
Chlorpromazine
Reserpine
Patient with ACTH deficiency
What test will distinguish a hypothalamic CRH deficiency from pituitary ACTH deficiency
CRH stimulation test
Dx if absent ACTH responsiveness to CRH
Pituitary corticotropin deficiency
Two test will stimulate the entire HPA
Insulin-induced hypoglycemia test
Glucagon test
Condition defined by a relative or absolute insuffeciency of vasopressin secretion from posterior pituitary
Diabetes insipidus
How to diagnose central DI
Water deprivation test
Tx of choice for central DI
Exogenous vasopressin
Postpartum failure to lactate
Postpartum amenorrhea
Progressive signs and symptoms of adrenal insufficiency
Dx
Sheehan’s syndrome
MC type of pitutary adenoma
Prolactin-secreting and null-cell (chromophobe adenoma)
MC functional pituitary tumor
Prolactinoma
MC presenting symptom of prolactinoma in females
Secondary amenorrhe
Pharma agent effective in reducing serum prolactin, tumor mass and inhibit tumor growth
Bromocriptine (dopaminergic agonist)
Hypersecretion of ACTH by pituitary
Cushing disease
Hypertension
DM
Goiter
Hyperhidrosis
Metabolic manifestation of acromegaly
Confirmatory test for acromegaly
Glucose suppresion test
Oral 100g of glucose fail to supress the GH level to less than 5ng/mL at 60mins
Tx of GH producing pituitary adenoma
Surgical excision
Medical - octreotide
Surgucal approach to pituitary
Transnasal
Trans sphenoidal approach
Hormones synthesized and secreted by adrenal CORTEX
Cortisol
Aldosterone
Adrenal androgen
Estrogen
Hormones synthesized by adrenal MEDULLA
Epinephrine
Norepinephrine
Enkephalins
Neuropeptide Y
Corticotropin-releasing hormone
Adrenal Corticosteroid hypersecretion
Cushing SYNDROME
Pt with palpitations
Headache
Emesis
Pounding pulse
Retinitis
Dx?
Pheochromocytoma
Embryonic origin of adrenal cortex
Coelomic mesothelial cells
Embryonic origin of adrenal Medulla
Ectodermal neural crest cells
Primary neurotransmitter of sympathetic postganglionic fibers
Norepinephrine
Ectopic adrenal medullary cells located lateral to aprta, near origin of inferior mesenteric artery
Glands of Zuckerland
Arterial supply of adrenal gland
Superior suprarenal artery
Inferior suprarenal artery
Branch from Inferior phrenic artery
Innervation of adrenal medulla
Preganglionic sympathetic neuron from celiac and renal plexus via splanchnic nerves
Drainage of Right adrenal vein
Posterior Inferior vena cava
Most circulating plasma cortisol is bound to this protein
Cortisol-biding globulin (CBG) , although small amounts are bound to albumin and other plasma proteins
Effect of glucocorticoids on insulin and glucagon
Stimulates production of glucagon and inhibit secretion of insulin
Aldosterone physiologic action
Reabsorb Sodium and excretion of Potassium, Hydrogen, and ammonia from the renal tubules
Stimulates active sodium and potassium transport in epithelial tissue (sweat glands, GU mucosa and saliva)
MC cause of Cushing Syndrome
Pituitary adenoma
MC causes ectopic ACTH secretion
Small Cell CA of lung
Expected result of Dexamethasone supression test in a pt with ectopic source of ACTH secretion
Dexamethasone should fail to supress cortisol secretion
Sex steroids produced in?
Zona reticulosis of adrenal cortex
Initial eval in pt suspected to have Cushing’s syndrome
Urinary-free cortisol level (markedly elevated) and a low dose decamethasone supression test (no supresion of cortisol)
Elevated cortisol
Elevated plasma ACTH
Persistent elevation of free cortisol after low and high dose dexamethasone administration
Ectopic source of ACTH
Useful test to differentiate hypercortisolism caused by pituitary source of ACTH vs ectopic source of ACTH
Dexamethasone supression test
Metyrapone test
MC cause of primary hyperaldosteronism
Solitary adrenal adenoma
Enzymatic deficiency associated with most cases of adrenogenital syndrome (Congenital Adrenal Hyperplasia)
21- hydroxylase
Marked hyperpigmentation of skin and visual disturbance
Dx,
Nelson syndrome
MC cause of acute adrenocortical insufficiency
Withdrawal of chronic steroid therapy
MC cause of Spontaneous adrenal insufficiency
Autoimmune dectruction of adrenal glands (>80%)
MC associated disorder in pt with autoimmune adrenocortic insufficiency
Hashimoto’s thyroiditis
Acute adrenal hemorrhage secondary to sepsis (classically meningococcal)
Waterhouse-Freiderichsen syndrome
Most useful test to evaluate pt suspected having adrenocortical insufficiency
Rapid ACTH stimulation test
Test of choice to distinguish hyperplasia from an adenoma as the cause of primary hyperaldosteronism
Measure plasma aldosterone concentration after change in posture
** only pt with adenoma experience postural decrease in aldosterone**
Serum abnormalities seen in functional cortisone secreting adrenal adenoma
High 24hr urine cortisol
Low ACTH level
Stimuli causes adrenal secretion of catecholamines
Hypoxemka
Hypoglycemia
Change in temp
Pain
Shock
CNS injury
Local wound factors
Endotoxin
Severe respiratory acidosis
Dx test to confirm Pheochromocytoma
Urine metanephrines
MC location of Neuroblastoma
Intra abdominal or retroperitoneal (60-70%)
Classic electrolyte finding in hyperaldosteronism
Hypernatremia
Hypokalemia
Syndromes associated with pheochromocytoma
MEN2a
MEN2b
Von Recklinghausen disease
Tuberous sclerosis
Sturge-weber disease
Stimulates uterine contraction during labor
Elicit milk ejection by myoepithelial cells of the mammary ducts
Oxytocin
Onlu hypervascular pancreatic neoplasm in angiography
Pancreatic Neuroendocrine tumors
Fasting glucose <45 and relief of symptoms with glycose
High N and C trrminus of insulin in blood (exogenous insulin with C terminus only)
Most common islet tumor and benign in 90% of cases
Insulinoma
High malignant potential
Most frequent islet cell tumor in MEN syndromw
High gastrin level
Severe peptic ulcer disease
Most located in gastrinoma triangle between CBD/cystic duct junction, 3rd portion of duodenum and gallbladder
Gastrinomas
Order of sympathetic blocking medication administration preoperatively for pheochromocytoma
Alpha blocking preoperative (PHENOXYBENZAMINE) with PRN periop B blockade as 2ndary measure
