Endocrine

Question 1

Answer 1

Xanthelesmas, a type of xanthoma, are yellowish macules/papules found on the medial eyelids; they are dermal accumulations of mo containing cholesterol and triglycerides; an LDL receptor abnormality is the most common cause

Question 2

Congenital hypothyroidism

Answer 2

TSH resistance due to a mut in a TSH receptor gene; characterized by increased TSH and low thyroxine; thyroid gland is normal in size and location

Question 3

Sulfonylureas

Answer 3

(glipizide) inhibit the ATP-sensitive K+ ch on the pancreatic beta cell inducing depolarization and L-type Ca2+ ch opening; increased Ca2+ influx stimulates insulin release independent of [blood glucose] increasing the risk of hypoglycemia when meals are missed or during exercise

Question 4

Pheochromocytoma

Answer 4

a tumor arising from the chromatin cells of the adrenal medulla characterized by excess production of catecholamines; presents w episodic HTN, diaphoresis, and palpitations tumor cells show electron-dense membrane bound secretory granules and immunohisto show (+) synaptophysin, chromogranin and neuron-specific enolase

Question 5

Postoperative hypoparathyroidism

Answer 5

hypocalcemia is a common complication due to inadvertent injury or removal of the parathyroid gland; postoperative supplementation with oral Ca2+ and vitamin D can be used to prevent postoperative hypocalcemia

Question 6

SGLT-2 inhibitors

Answer 6

Canagliflozin and Dapagliflozin
decrease renal reabsorption of glucose and Na+ resulting in osmotic diuresis and natriuresis leading to reduced BP and decreased mortality rate in HF pts

Question 7

long term use of exogenous glucocorticoids

Answer 7

causes suppression of the HPA which leads to b/l adrenocortical atrophy involving the zona fasciculata and reticularis; cessation can lead to adrenal crisis

Question 8

NE to epi

Answer 8

cortisol increases the conversion of NE to epi in the adrenal medulla by increasing the expression of phenylethanolamine-N-methyltransferase (PNMT)

Question 9

Primary adrenal insufficiency

Answer 9

autoimmune destruction of the b/l adrenal cortex; reduced aldosterone (renal salt wasting w hypovolemia, hypotension, and hyperkalemia); reduced cortisol causes decreased EPI w a compensatory increase in NE

Question 10

Smoking cessation

Answer 10

by far the most effective prevention in almost all pts, especially diabetics

Question 11

ATP-sensitive K+ channels

Answer 11

oxidative metabolism of glucose in pancreatic cells generate ATP; ATP-induced closure of ATP-sensitive K+ ch leads to membrane depolarization and subsequent insulin release

Question 12

Hyperaldosteronism

Answer 12

results in hypokalemia which causes muscle cramps, muscle weakness and paresthesia

Question 13

Gynecomastia and tx

Answer 13

development of glandular breast tissue in males and is commonly seen in men receiving androgen deprivation therapy for prostate cancer; tamoxifen inhibits the effect of estrogen on breast tissue and can reduce the risk

Question 14

Hirsutism

Answer 14

male-pattern hair growth in a women most common cause is PCOS; combination contraceptive pills can tx by suppressing pituitary LH secretion and subsequently decreasing ovarian androgen production

Question 15

Causes of increased risk of hypoglycemia in DM1

Answer 15

pts w DM1 are at increased risk of hypoglycemia because exogenous insulin will continue to be absorbed from the injection site despite failing glucose levels; long standing diabetes will cause alpha-cell (glucagon) failure leading to decreased glucagon secretion which leads to a greater risk for hypoglycemia

Question 16

Methimazole

Answer 16

thioamides (methimazole and propylthiouracil) decrease the formation of thyroid hormones via inhibition of thyroid peroxidase enzyme responsible for both iodine organification and coupling of iodotyrosines; PTU also decreases peripheral conversion of T4 to T3

Question 17

Excess production of ACTH

Answer 17

trophic hormone for zona fasciculata and reticularis; excess ACTH causes increased cortical (Cushing’s) and increased androgens (irregular menses, hirsutism)

Question 18

Embryology of adrenal medulla

Answer 18

neural crest cells; multipotent, migratory cells that originate in ectoderm; also gives rise to melanocytes and neural ganglia

Question 19

Gherlin

Answer 19

stimulates appetite and promotes weight gain; caloric restriction leads to increased gherlin levels along w decreased insulin and leptin levels causing an increase in appetite that can make it difficult to maintain weight loss

Question 20

21-hydroxylase deficiency

Answer 20

most common form of congenital adrenal hyperplasia; excess stimulation of the adrenal cortex by ACTH; presentation of non-salt wasting, early virilization (2-4 yrs), accelerated linear growth and elevated 17-hydroxyprogesterone and androgens

Question 21

21-hydroxylase deficiency tx

Answer 21

low doses of exogenous corticosteroids to suppress excess ACTH secretion, which reduces production of androgens by the adrenal cortex

Question 22

physiological insulin secretion

Answer 22

admin of long-acting and rapid-acting insulin analogues; long-acting (ex: glargine) replicate basal insulin and rapid-acting (ex: lispro) replicate meal-related insulin surges

Question 23

pituitary apoplexy

Answer 23

acute pituitary hemorrhage (pituitary apoplexy) is characterized by severe HA, bitemporal hemianopsia and ophthalmoplegia (CN III); occurs in preexisting adenoma; it is an medical emergency that requires urgent tx w glucocorticoids to prevent adrenal crisis and circulatory collapse

Question 24

Injectable or intranasal glucagon

Answer 24

severe hypoglycemia causing impaired consciousness can be tx by glucagon which rapidly corrects hypoglycemia by increasing hepatic glycogenolysis, resulting in release of glucose from pre-existing hepatic glycogen storage

Question 25

Maple syrup urine disease

Answer 25

presents within the first few days of life with irritability, dystonia, poor feeding and sweet-smelling urine; dietary restriction of branched chain amino acids (leucine, isoleucine and valine) is required

Question 26

brown adipose cells

Answer 26

contain multiple lipid droplets and abundant mitochondria, produce large amounts of heat (thermogenesis) by uncoupling oxidative phosphorylation w the protein thermogenin; preterm infants are at increased risk for hypothermia because they have less brown adipose tissue

Question 27

Hypothyroidism effects on lipids

Answer 27

causes decreased expression of LDL receptors in the liver leading to decreased clearance of LDL and increased blood LDL levels; also causes hypertriglyceridemia due to decreased expression of lipoprotein lipase; pts are at increased risk for coronary atherosclerosis

Question 28

hyperthyroid induced bone loss

Answer 28

causes increased bone turnover w net bone loss potentially leading to osteoporosis; bone loss is driven by T3 which stimulates osteoclast differentiation, increased bone resorption and release of Ca2+

Question 29

hypothyroid myopathy

Answer 29

presents w myalgias, proximal muscle weakness, elevated creatinine kinase, delayed relaxation of DTRs; dx can be confirmed by elevated TSH

Question 30

Ketones

Answer 30

when glycogen stores are depleted during fasting, ketone bodies are produced in the liver and can be used as an energy source in the mitochondria; preferentially the brain; erythrocytes lack mitochondria and unable to use ketones

Question 31

thyroid migration

Answer 31

thyroid gland is formed from evagination of the pharyngeal epithelium and descends to the lower neck; due to failure of *migration the thyroid can reside anywhere along the thyroglossal duct's usual path, including the tongue (lingual thyroid)

Question 32

tx of prolactinoma

Answer 32

prolactin-secreting pituitary adenoma is tx w dopamine agonist (ex: cabergoline); suppresses prolactin production and reduce tumor size; benefits are typically seen within the first few weeks

Question 33

hypercalcemia-induced constipation

Answer 33

hypercalcemia inhibits nerve depolarization, leading to impaired smooth muscle contraction and reduced motility; symptoms include constipation, cramps abdominal pain and nausea

Question 34

Thyroid hormone resistance

Answer 34

thyroid hormone resistance is characterized by decreased sensitivity of peripheral tissues to thyroid hormones due to defect in the thyroid receptor; T3, T4 and TSH will all be elevated; presents as goiter and ADHD

Question 35

somatostatinoma associated biliary stones

Answer 35

somatostatin inhibits CCK; decreased CCK leads to decreased gallbladder contractility; increased risk for biliary stones

Question 36

Growth hormone signal transduction

Answer 36

GH binds to cell surface receptors leading to intracellular activation of JAK-STAT pathway; cytokines and hematopoietic GFs also use this pathway

Question 37

Papillary thyroid carcinoma

Answer 37

most common type of thyroid cancer; large cells w nuclei containing finely dispersed chromatin, giving them an empty or ground-glass appearance (ex: Orphan Annie eye), as well as intranueclear inclusions and nuclear grooves

Question 38

Answer 38

most common type of thyroid cancer; large cells w nuclei containing finely dispersed chromatin, giving them an empty or ground-glass appearance (ex: Orphan Annie eye), as well as intrnueclear inclusions and nuclear grooves

Question 39

Canagliflozin and Dapagliflozin MOA

Answer 39

SGLT2 inhibitors decrease renal reabsorption of glucose and Na+ leading to increased urinary glucose excretion and decreased BG levels; increased natriuresis and osmotic diuresis lead to a small decrease in Extracellular fluid volume, total body Na+ content and BP

Question 40

SGLT2 inhibitors

Answer 40

Canagliflozin and Dapagliflozin; tx for DM2; decrease renal reabsorption of glucose and Na+ leading to increased urinary glucose excretion and decreased BG levels

Question 41

Insulin-induced weight gain

Answer 41

insulin can cause weight gain due to physiologic and behavioral factors; counseling should elicit the pts perspective on appetite, changes in dietary patterns and hypoglycemic symptoms

Question 42

neonatal hypoglycemia

Answer 42

common in infants in diabetic mothers; pathophysiology involves maternal hyperglycemia which in turn causes fetal hyperglycemia and compensatory hyperfunctioning of the pancreas (hyperinsulinemia); after birth persistently elevated insulin levels lead to transient hypoglycemia

Question 43

Testosterone replacement therapy

Answer 43

indicated for men w symptomatic hypogonadism; associated w an increase in serum prostate-specific antigen and may increase risk of prostate cancer; can also cause erythrocytosis (leading to thromboembolism) and hematocrit

Question 44

CF-related diabetes

Answer 44

cystic fibrosis (CF) causes the accumulation of thick, viscous secretions in ducts throughout the body; CF-related diabetes occurs after the progressive destruction of pancreatic islet cells leads to decreased insulin production

Question 45

Graves disease drug-induced neutropenia

Answer 45

drug-induced neutropenia is the major side effect of 1st line meds used to tx Graves; initial manifestations usually include fever and oropharyngeal ulcers

Question 46

Metyrapone stimulation test

Answer 46

admin of metyrapone will cause a decrease in cortisol synthesis via inhibitor of 11B hydroxylase; in pts with an intact HPA axis this will cause a reactive increased in ACTH, 11-deoxycortisol (DOC) and urinary 17-hydroxycorticosteroid

Question 47

Prolactin-secreting tumors on GnRH HPA axis

Answer 47

elevated prolactin levels suppress the release of GnRH, leading to decreased LH and impaired testosterone production in men

Question 48

hCG testicular germ cells induced gynecomastia

Answer 48

secretion of hCG by testicular germ cell tumors impairs testosterone production in Leydig cells while increasing aromatase activity and conversion of androgens to estrogens; resulting increase in estrogen/androgen ration can cause gynecomastia

Question 49

Sorbitol accumulation

Answer 49

in hyperglycemic states, aldose reductase converts glucose to sorbitol at a rate faster than sorbitol can be metabolized; sorbitol accumulates in certain cells, lens, leading to cataracts

Question 50

Polyol pathway

Answer 50

aldose reductase converts glucose into sorbitol which is slowly metabolized into fructose by sorbitol dehydrogenase

Question 51

Osteoporosis associated w chronic admin of GnRH agonist

Answer 51

chronic GnRH agonist (ex: leuprolide) suppresses pituitary LH release and leads to reduced production of testosterone; lower levels of circulating testosterone produces a clinical effect similar to orchiectomy and can lead to accelerates bone loss and increased risk for osteoporosis

Question 52

SERMs

Answer 52

Tamoxifen and Raloxifene selective estrogen receptor modulator (SERM) has estrogen agonist activity on bone and decreases bone resorption; increase the risk for venous thromboembolisms

Question 53

Anorexia nervosa on functional hypothalamic amenorrhea

Answer 53

functional hypothalamic amenorrhea is a common cause of secondary amenorrhea and occurs due to decreased amplitude and frequency of pulsatile GnRH leading to low FSH, LH and estrogen; causes are anorexia, excessive strenuous exercise and chronic illness

Question 54

metformin

Answer 54

Question 55

metformin

Answer 55

lowers blood glucose by reducing hepatic gluconeogenesis and increasing insulin-dependent peripheral glucose uptake; lactic acidosis is a rare complication of metformin therapy; the risk is increased in pts w underlying renal insufficiency

Question 56

Postpartum thyroiditis

Answer 56

occurs within 12 months of pregnancy and is characterized by autoimmune destruction of thyroid follicles; typically begins w a hyperthyroid phase due to the release of preformed thyroid hormone, followed by a hypothyroid phase due to depletion of thyroid hormone and an eventual return to a euthyroid state; histo - lymphocytic infiltration w the formation of germinal centers (similar to chronic lymphatic Hashimoto thyroiditis)

Question 57

pharmacokinetic profiles of common insulin preparations

Answer 57

regular insulin has a rapid onset and short half-life allowing the rapid adjustments needed for DKA; peaks in 2-4 hrs and lasts 5-8 hrs

Question 58

functional hypothalamic amenorrhea

Answer 58

results from loss of pulsatile GnRH release from the hypothalamus and is caused by weight loss, strenuous exercise, systemic illness or abnormal eating habits

Question 59

proinsulin: insulin and c-peptide

Answer 59

proinsulin is cleaved into insulin and c-peptide; c-peptide is a marker of endogenous insulin secretion; diabetic meds that increase endogenous insulin secretion (ex: sulfonylureas) elevate the c-peptide levels

Question 60

thyroid peroxidase (TPO)

Answer 60

TPO catalyzes the oxidation of iodide to iodine, the iodination of thyroglobulin tyrosine residues and the iodotyrosine coupling reaction that forms T3 and T4; antibodies against TPO are present >90% of pts w Hashimoto thyroiditis

Question 61

primary hyperaldosteronism (Conn syndrome)

Answer 61

caused by excessive aldosterone secretion, typically due to an aldosterone-producing adrenal adenoma or b/l nodular hyperplasia of the zona glomerulosa; presents HTN, low plasma renin, hypokalemia and metabolic alkalosis

Question 62

Vasopressin and oxytocin release

Answer 62

synthesized and packages w carrier proteins (neurophysins) within neurons found in the hypothalamus; hormones are transported down axonal projections to the posterior pituitary (neurohypophysis) where they are secreted into circulation

Question 63

Autoimmune insulinitis

Answer 63

progressive beta cell loss; most common cause of DM1

Question 64

MEN type 2

Answer 64

caused by a gremlin activating mut in RET photo-oncogene and frequently results in both medullary thyroid cancer and pheochromocytoma;

Question 65

Exercise, insulin & glucose transport

Answer 65

glucose uptake in skeletal muscle occurs primarily via GLUT4; muscle contraction and insulin induce translocation of GLUT4 to the cell surface increasing glucose uptake during exercise and lower BG levels

Question 66

Stress hyperglycemia

Answer 66

transiently elevated BG levels in context of severe illnesses (sepsis, burns, major hemorrhage) in pts w/o preexisting diabetes cortisol and catecholamines released in response to severe metabolic stress act on the liver to increase glycogenolysis and gluconeogenesis

Question 67

beta blockers in thyrotoxicosis

Answer 67

beta blockers (ex: propranolol) provide rapid relief of the adrenergic-mediated symptoms of thyrotoxicosis and can be given while awaiting diagnostic evaluation and definitive management

Question 68

Inhibit B

Answer 68

LH stimulates the release of testosterone from the Leydig cells of the testes; FSH stimulates the release of inhibin B from Sertoli cells in the seminiferous tubules; inhibin B induce negative feedback on FSH

Question 69

Secondary hyperthyroidism

Answer 69

most common cause is a TSH-secreting pituitary adenoma; elevated TSH, T3 and T4

Question 70

5-alpha reductase deficiency

Answer 70

converts testosterone to DHT; mediates development of the external genitalia in the male fetus; male neonates with 5-alpha reductase deficiency are born w ambiguous genitalia that typically masculinize at puberty

Question 71

Klinefelter syndrome

Answer 71

47, XXY causes infertility characterized by primary hypogonadism (elevated FSH and LH and low testosterone) and azoospermia

Question 72

DM risk for cardiovascular events

Answer 72

coronary heart disease is the most common cause of death in pts with DM

Question 73

changes in male hormone levels w age

Answer 73

normal aging in men is associated w slow decline in gonadal testosterone production, compensatory rise in LH and rising serum levels of sex hormone-binding globulin; nonspecific symptoms of decreased ejaculate volume, increased erectile latency and sexual refractory time

Question 74

Aromatase inhibitors

Answer 74

anastrozole, letrozole, exemestane; aromatase inhibits decrease the synthesis of estrogen from androgens, suppressing estrogen levels and slowing progression of ER (+) tumors

Question 75

Hormone sensitive lipase

Answer 75

found in adipose tissue where it functions to drive the breakdown of stored triglycerides into FFAs and glycerol; during times of starvation, this enzyme provides substrates for hepatic gluconeogenesis and ketone formation

Question 76

Familial chylomicronemia syndrome type I

Answer 76

defect in lipoprotein lipase; elevated chylomicrons; major manifestations: acute pancreatitis

Question 77

hyperosmotic volume contraction

Answer 77

hyperosmotic volume contraction is caused by loss of free water (w retention of electrolytes); can occur in pts w diabetes insipidus or as a result of decreased fluid intake/excessive sweating

Question 78

Sheehan syndrome

Answer 78

high estrogen levels during pregnancy causes enlargement of the pituitary gland w/o a proportional increase in blood supply; permpartum hypotension can cause ischemic necrosis of the pituitary leading to panhypopituitarism (Sheehan syndrome); pts commonly develop failure of lactation due to deficiency of prolactin

Question 79

osteoclast differentiation

Answer 79

PTH directly stimulates osteoblasts leading to bone formation; expression of RANKL on osteoblasts indices increased bone resorption via paracrine effect on nearby osteoclast; hyper-PTH causes increased RANKL expression and decreased expression of osteoprotegrin leading to net bone loss

Question 80

G protein-coupled receptors on pancreatic beta cells

Answer 80

alpha-2 adrenergic receptors inhibit insulin secretion and beta-2 adrenergic receptors stimulate insulin secretion

Question 81

VitD deficiency caused by anticonvulsants

Answer 81

catabolism of VitD is initiated by CYP24A1 (aka 24-hydroxylase); expression of this enzyme is induced by phenytoin and other anticonvulsants (ex: carbamazepine), which can lead to increased breakdown of VitD and lead to VitD deficiency

Question 82

thyroid lymphoma

Answer 82

primary lymphoma of the thyroid is characterized by rapidly progressive thyroid enlargement, often w compression of surrounding structures; thyroid lymphoma is uncommon, but the incidence is significantly greater in pts w preexisting chronic autoimmune Hashimoto's thyroiditis