Endocrinology Flashcards
Compare Nervous system and Endocrine system
Nervous: rapid response, short-duration response, acts via AP and Neurotransmitters, acts at specific locations, act over short distances
Endocrine: slow response, long duration response, acts via hormones into blood, acts at diffuse locations, and hormones act over long distance
Autocrine
chemical that exerts effects on same cells that secrete them
Paracrine
locally acting chemicals that affect cells other than those that secrete them
Water-soluble hormones
amino-acid except thyroid
act on plasma membrane receptors
act vis G proteins second messengers
cannot enter cell
Lipid-Soluble hormone
steroid and thyroid hormone
act on intracellular receptors that directly activate genes
can enter cell
Compare cAMP and PIP2-Ca signaling mechanism
cAMP: hormone binds to receptor-> activates G protein -> activates or inhibits adenylate cyclase -> adenylate cyclase then convert ATP to cAMP -> cAMP activates protein kinase to phosphorylate other proteins
PIP2-Ca: hormone on membrane activates G protein -> activates phospholipase C -> splits PIP2 into diacylglycerol activate protein kinase and inositol triphosphate release Ca
Intracellular Receptor mechanism
lipid-soluble hormones and thyroid hormone can diffuse into target cell bind to intracellular receptors -> enters the nucleus and binds to specific region of DNA -> helps initiate DNA transcription to produce mRNA -> mRNA then translated into specific protein
Stimulation of Endocrine Gland
Humoral stimuli: changing blood levels of ions and nutrients directly stimulate secretion of hormones
Neural stimuli: nerve fibers stimulate hormone release
Hormonal Stimuli: hormone stimulate other endocrine organs to release their hormones
Posterior pituitary
composed of neural tissue that secrete neurohormones
Anterior pituitary
consists of glandular tissue
ADH Regulation
Stim: by impulses from hypothalmic neurons in response to ncreased blood solute concentration or decreased blood vol; also timulated by pain, some drugs, low BP
inhib: adequate hydration of body and alcohol
ADH Target organ and effect
kidneys: stimulates tubule cells to reabsorb water from the forming urine back into blood
ADH patho
↑ syndrome of inappropriate ADH secretion
↓ diabetes insipidus
T4 composition
DIT plus DIT
T3 composition
DIT plus MIT
Where is Iodide located in the thyroid gland?
cytoplasm of follicular cells
T3 Function
7 Bs
brain maturation, bone growth, B adrenergic effects, basal metabolic rate, blood sugar, break down lipids, babies stimulates surfactant synthesis
What is T3 impact on heart?
increase cardiac output, HR, SV, and contractility
Oxytocin regulation
stim: impulses from hypothalamic neuros in response to stretching of the uterine cervix or sucking of infant at breast
inhib: adequate hydration of the body and by alcohol
Oxytocin pathway
neurons in paraventricular nucleus of hypothalamus
Oxytocin target organ and effect
uterus: stimulates uterine contractions, initiates labor
breast: initiates milk ejection
Wolff-Chaikoff effect
sudden exposure to excess iodine temporarily turns off thyroid peroxidase; dec T3/T4 production
reg: chemoreceptors locally of thyroid tissue
protective autoregulation
GH reg
stim: by GHRH which is triggered by low blood levels of GH, deep sleep, hypoglycemia, increases in blood levels of amino acids, low levels of fatty acids, exercise, and other types of stressors
inhib: feedback inhibition exerted by GH and IGFs, hyperglycemia, hyperlipidemia, obesity, and emotional deprivation via either increased somatostatin or decreased GHRH release
GH Target organ and effect
liver, muscle, bone, cartilage, and other issues: anabolic hormone, stimulates somatic growth, mobilizes fats, spares glucose
growth-promoting effects mediated indirectly by IGFs
GH patho
↑ gigantism in kids, acromegaly in adults
↓ dwarfism in kids, GH insufficiency in adults
TSH reg
stim: by TRH and in infants indirectly by cold temperature
inhib; by feedbakci nhibitiion exerted by thyroid hormones on ant pituitary and hypothalamus and by GHIH
17 aplha-hydroxylase patho
increase in progesterone and aldosterone
decrease in cortisol and sex hormone
17 aplha-hydroxylase clinical
a typical genitalia, undescended testes, lack of secondary sexual development, hypertension, hypokalemia,
21-hydroxylase patho
allow the sex hormones to go forward, low cortisol and aldosterone
21-hydroxylase clinical char
salt wasting, hypotension, and hyperkalemia
11beta-hydroxylase patho
stops conversion of 11-deoxycortisoterone to corticosterone and stops conversion of 11-deoxycortisoal (increases BP) to cortisol
cortisol and aldosterone decrease
increased androgens
11beta-hydroxylase clinical
hypokalemia, hypertension,
posterior pituitary hormones (made by hypothalmic neurons, stored in post pituitary)
oxytocin, antidiuretic hormone (ADH)
oxytocin chemical structure and cell type
peptide, mostly from neurons in paraventricular nucleus of hypothalamus
antidiuretic hormone (ADH) other names, chemical structure and cell type
vasopressin
peptide, mostly from neurons in supraoptic nucleaus of hypothalamus
growth hormone (GH) chemical structure and cell type
protein, somatotropic cells
thyroid stimulating hormone (TSH) chemical structure and cell type
glycoprotein, thyrotropic cells
TSH target organs and effects
thyroid gland: sitmulates thyroid gland to release thyroid hormones
TSH patho
↑ primary hyperthyroidism, secondary/tertiary hypothyroidism, graves, pituitary adenoma
↓ primary hypothyroidism; may cause myxedema, secondary/tertiary hyperthyroidism
adrenocorticotropic hormone (ACTH) chemical structure and cell type
peptide, corticotropic cells
ACTH regulation
stimulated: by CRH; stimuli that increase CRH release include fever, hypoglycemia, and other stressors
inhib; feedback inhibition exerted by glucocorticoids
ACTH target organs and effects
adrenal cortex: promotes release of glucocorticoids and androgens (mineralcorticoids to a lesser extent)
ACTH patho
↑ cushings disease
↓ rare
follicle-stimulating hormone (FSH) composition
glycoprotein, gonadotropic cells
FSH regulation
stimulated; GnRH
inhibi; by feedback inhibition exertion by inhibin, and estrogens in females and testosterone in males
FSH target organ and effect
ovaries and testes
in females, stimulates ovarian follice maturation and production of estrogens
in males, stimulates sperm production
FSH patho
↑ no important effects
↓ failure of sexual maturation
luteinizing hormone (LH) composition
glycoprotein, gonadotropic cells
LH regulation
stim; GnRH
inhib; feedback inhibition exerted by estrogens and progesterone in females and testosterone in males
LH target organ and effects
ovaries and testes;
females: triggers ovulation, stimulates ovarian production of estrogens and progesterone
males; promotes testosterone production
LH patho
same as FSH
↑ no important effects
↓ failure of sexual maturation
prolactin (PRL) composition
protein, prolactin cells
PRL regulation
stim; decreased PIH; release enhanced by estrogens, birth control pills, breastfeeding, dopamine blocking drugs
inhib; PIH (dopamine)
PIH target organ and effects
breast secretory tissue; promotes lactation
PRL patho
↑ inappropriate milk proiduction (galactorrhea); cessation of menses in females, impotence in males, low libido, gonadal dysgenesis
↓ poor milk production in nursing women, hypopituitarism, excessive dopamine, D2 agonists
anterior pituitary hormones
GH, TSH, ACTH, FSH, LH, PRL
where is insulin synthesized and by what cells
beta cells in pancreas
insulin chemical composition
2 amino acid chains connected by disulfide linkages
explain the processes of insulin synthesis
preproinsulin > proinsulin > exocytosis of insulin and C peptide equally
synthesized by beta cells in pancreas
describe insulin release and circulation
insulin is secreted into blood via secretory granules; unbound circulation in blood
half life 6 min, clearance 10-15 min
degraded by insulinase in the liver
why is c peptide measurement useful in type I diabetics?
determines how much natural insulin is being produced
explain the activation of target cells by insulin
within secs of insulin binding to membrane receptors, 80% of body cells increase glucose uptake (esp muscle and adipose, not neurons in brain)
increased glucose transport into cells > converted into energy
cell membrane more permeable to AA, K+, P+
adjustment of activity levels of enzymes intraceullatrly occur over 10-15 mins
changes rate of transcription and translation at the DNA and RNA level
hypothalamus hormones
TRH, CRH, GhRH, GhIH, GnRH, Dopamine/prolactin inhibiting factor, somatostatin, Vasopressin and oxytocin
what are the hormones released by thyroid?
thyroxine (T4)
triiodothyronine (T3)
calcitonin
adrenal cortex hormones
cortisol
aldosterone
adrenal medulla hormones
norepinephrine/epinephrine
pancreas hormoens
insulin
glucagon
parathyroid hormones
parathyroid hormone
testes hormones
testosterone
ovaries hormones
estrogen and progesterone
what are steroid hormones synthesized from and stored? lipid or water soluble?
synthesized from cholesterol, not stored
lipid soluble
which hormones are amine hormones
thyroid and adrenal medullary hormones
what are amine hormones derived from
tyrosine
most hormones have what composition?
polypeptides and proteins
polypeptides > 100AA = proteins
polypeptides <100AA = peptides
what cellular component are most hormones synthesized on? where are they then transferred to?
synthesized on rough end of ER; prohormones transferred to golgi to be packaged into secretory vesicle where they are stored until needed
what is the metabolic clearance rate?
rate of removal of hormones from blood
rate of disappearance of hormone from plasma/concentration of hormone
how are hormones cleared from plasma
metabolic destruction by tissues, binding with tissues, excretion by liver into bile, excretion by kidneys into urine
what hormones have receptors in or on surface of the cell membrane
protein, peptide, catecholamine hormones
what hormones have receptors in the cell cytoplasm
steroid hormones
what hormones have receptors in the cell nucleus
thyroid hormones
what types of things cause down regulation of hormone receptors
inactivation of receptor molecules, inactivation of intracellular protein signaling molecules, destruction of receptors by lysosomes, decreased production of receptors, temp sequestration of receptor to inside of cell
what is a hormone receptor complex
formation of complex alters funciton of receptor > activated receptor imitates hormonal effects
describe an ion channel linked receptor
all neurotransmitter substances combine with receptors in postsynaptic membrane
change in structure of a receptor (opening/closing a channel for ions)
Na, K, Ca, etc
describe a G protein linked hormone receptor
activate receptors that indirectly regulate activity of target proteins by coupling with groups of cell membrane proteins > GTP (G) binding proteins
heterotrimeric guanosine triphosphate, 7-transmembrane segments
inhibitory and stimulating G proteins
describe an enzyme linked hormone receptor
proteins that pass through membrane only once; hormone binding site EC and catelytic/enzyme bindnig site IC
ex: tyrosine kinase > leptin receptor
describe IC hormone receptors; activation of genes
adrenal and gonadal steroid hormones, thyroid hormones, vit D, and retinoid hormons bind with protein receptors within the cell (lipid soluble, pass through plasma membrane)
activated complex binds with regulatory (promotor) sequence of DNA (hormone response element) > activation/repression of transcription of genes and mRNA
describe the adenylyl cylcase-cAMP second messenger system
hormone binds receptor > coupling of receptor to G protein
adenylyl cylase (membrane bound enzyme) > converts small amount of cAMP inside cell > acitvates cAMP dependent protein kinase > phosphorylates > enzyme cascade activated
small amount of hormone = large effect
describe the phospholipase C second messenger system
enzyme catalyzes breakdown of phospholipids in cell membrane
PIP2 (second messengers)
- inositol triphosphate (IP3) > mobilizes Ca ions from mitochondria and ER
- diacylglycerol (DAG) > activates enzyme protein kinase C
describe thyroid hormones INC gene transcription
T3 and T4 bind to receptors in nucleus (receptors = activated transcription factors within chromosomal complex); once bound to intranuclear receptors > thyroid hormones continue to express control function for days/weeks
control function of gene promotors
activate genetic mechanisms for synthesizing many types of IC proteins
what is the main role of the thyroid hormones
control bodys metabolic rate
what cellular component forms thyroglobulin
ER and golgi apparatus
how/where are T4/T3 formed
formed from tyrosine in thyroglobulin molecule
iodine binds with thyroglobin molecule = organification > can store 2-3 months of hormones
what is the iodide pump? what does it do/mechanism?
transports iodides from blood into thyroid cells/follicles
sodium iodide symporter (iodide trapping)
basal membrane of thyroid can pump iodide into the cell
symporter co-transports 1 iodide along with 2 sodium ions
where does the energy for the sodium iodide symporter come from
NA/K ATPase pump > pumps Na out of cell giving low IC Na conc and gradient for facilitated diffusion of Na into cell
melatonin comes from what gland?
pituitary
function of melatonin
regulates circadian rhythm and reproductive hormones
hypersecretion of melatonin can result in what
in children inhibits sexual development
regulation of melatonin
external light (-) seratonin
synthesis of melatonin
tryptophan > 5htp > seratonin > melatonin
what is necessary for the synthesis of thyroid hormone
iodine
in the synthesis of thyroid hormone, iodine transport is ___
active
structural difference between T3 and T4
T4 = 2 DIT residues T3 = 1 DIT residue + 1 MIT residue
structural difference between T3 and T4
T4 = DIT + DIT T3 = DIT + MIT
explain conversion of T4 > T3
follicles of thyroid 5’-deiodinase converts T4 to T3 in peripheral tissue
what factors inhibit peripheral conversion of T4 > T3
glucocorticoids, beta-blockers, propylthiouracil (PTU)
what is reverse T3 (rT3)
metabolically inactive byproduct of peripheral conversion of T4 and its production
what increases rT3
GH and glucocorticoids
functions of thyroid peroxidase
oxidation, organification of iodine, coupling of monoiodotyrosine (MIT) and diiodotyrosine (DIT)
explain the release of T4/T3 from thyroid gland
cleaved by thyroglobulin molecule > free hormone release
pinocytic vesicles enter thyroid cell > lysosomes fuse with vesicles > proteases digest thyroglobulin adn release T4/T3 > diffuse through base of thyroid cell to capillaries
how is T4/T3 transported to tissues
bound to plasma proteins (synthesized in liver) > thyroxine binding globulin
released slwoly to tissue cells > bind with IC proteins and stored
slow onset and long duration of action (long latent period) - max rate after 10-12 days
triiodothyronine (T3) functions
7 B’s
-Brain maturation
-Bone growth (synergistic with GH)
-B-adrenergic effects (increases B1 reeptors in heart > increased CO, HR, SV, contractility)
-Basal metabolic rate (via increased Na+/K+- ATPase leading to increased O2 consumption, RR, and body temp)
-Blood sugar (via glycogenolysis and gluconeogensesis)
-Break down lipids (through lipolysis)
Babies > stimulates surfactant synthesis
effects of thyroid functions
increase transcription of genes
increase cellular metabolic activity
effects on growth
effects on certain body functions
most thyroxine –>
triiodothyronine
prior to acting on genes to INC genetic transcription
1 iodide removed
where are thyroid hormone receptors in relation to DNA?
attached to DNA genetic strands OR located in proximity to them
thyroid hormone receptor forms a hetereodimer with retinoid X receptor (RXR) at specific parts of DNA
why is most thyroxine > triiodothyronine
IC thyroid receptors have high affinity for T3
what are the cellular metabolic activities of T4/T3
increased number, size, and activity of mitochondria
- total membrane surface area inc in proportion of inc metabolic rate of whole animal
- inc ATP production
increased active transport of ions through cell membranes
- Na+/K+ ATPase increased > inc rate of transport of Na and K ions through cell membranes > increases heat in body
- cell membrane = leaky to Na ions
thyroid function on body tissues
normal arterial presure
muscle tremor
effects on: plasma and liver fats muscle function sleep other endocrine glands sexual function
increased: vitamin requirement BMR blood flow and CO HR and heart strength respiration GI motility carb metabolism fat metabolism
decreased:
body weight
how does thyroid stimulate carb metabolism
rapid glucose uptake by cells, increased glycolysis, increased insulin secretion
how does thyroid stimulate fat metabolism
lipids mobilized rapidly from fat tissue, decreasing fat stores in body
what is the thryoid effect on plasma and liver fats
increased thyroid hormone > decreased concentration of cholesterol, phospholipids, and TGs BUT increased free fatty acids
explain why thyroid > increased vitamin requirement
inc body enzymes, including vitamins. vitamin def with too much thyroid
how does thyroid increase blood flow and CO
inc tissue metabolism > inc oxygen use > vasodilation
what regulates thyroid secretion?
thyrotropin (TSH) inc thyroid secretion
TRH > stimulates TSH release > stimulates follicular cells
negative feedback control through free T3/T4
- ant pit > dec sensitivity to TRH
- hypothalamus > dec TRH secretion
thyroxine binding globulin (TBG) binds most T3/T4 in blood (making it inactive)
functions of TSH
increased:
proteolysis of thyroglobulin (w/in 30 mins)
activity of iodide pump
iodination of tyrosine
size and secretory activity of thyroid cells
# of thyroid cells
explain thyroid regulation via cyclic adenosine monophosphate
(activation of second messenger cAMP system of cell)
TSH binds with TSH receptors on basal membrane of thyroid cell > adenlyl cylase activated in membrane > inc cAMP formation inside cell, which acts as a 2nd messenger to activate protein kinase > phosphorylations t/o cell > immediate release in secretion of thyroid hormones and prolonged growth of thyroid gland tissue
chemical composition of TSH/thyrotropin
glycoprotein
chemical composition of TRH
tripeptide amide
explain TRH regulation of TSH secretion
TRH secreted by hypothalamus, acts on ant pit to regualte TSH secretion
binds with TRH receptors in pituitary cell membrane > activation of phospholipase 2nd messenger system inside cells > large amts of phospholipase C produced > 2nd messengers inc Ca ions > release of TSH
how does cold exposure affect TRH/TSH
cold exposure > excitation of hypothalmic centers for body temp control > inc TSH > > BMR inc 15-20%
explain the effect of excitement/anxiety on TSH
anxiety/excitement stimulate sympathetic nervous system > dec in TSH secretion
how does prolonged fasting affect TRH
TRH neurons in PVN receive input from leptin responsive neurons of hypothalamus that regulate energy balance
prolonged fasting > dec leptin > indirectly inhibits TRH neurons > dec thyroid hormone secretion
compare TSH and FT4 levels in hyper- and hypo- thyroidism
hyperthyroidism: low TSH, high FT4
hypothyroidism: high TSH, low FT4
explain common clinical characteristics of hyperthyroidism
high excitability, sweating, heat intolerance, wt loss, diarrhea, muscle weakness, nervousness, fatigue, insomnia, tremor
chemical comp melatonin
amine
TRH hypersecretion patho
increased TRH in 1 or 2 degree hypothyroidism may increase prolactin secretion > galactorrhea
hyposecretion of melatonin can lead to..
insomnia
functions TRH
increases TSH and PRL
functions GnRH
increases FSH/LH
functions GHRH
increases GH
functions CRH
increases ACTH/MSH/B-endorphin
dec in chronic steroid use
function somatostatin
dec GH and TSH
functions dopamine
dec PRL and TSH
chemical comp GH/somatotropin
protein
chemical comp prolactin PRL
protein
chemical comp FSH
glycoprotein
chemical comp LH
glycoprotein
chemical comp TSH
glycoprotein
chemical comp ACTH
peptide
chemical comp oxytocin
peptide
chemical comp insulin
peptide
chemical comp glucagon
protein
chemical comp epi/norepi
amide
TRH originating organ
hypothalmic paraventricular nucleus
somatostatin originating cells
delta cells of hypothalamus
GH/somatotropin functions
stim linear growth and muscle mass through IGF1
increases insulin resistance
prolactin PRL originating cell
lactotrophs of ant pituitary
oxytocin originating cells/organs
hypothalamus; magnocellular cells of supraoptic and paraventricular nucleus
stored and secreted by post pituitary
calcitonin originating cells
parafollicular C cells of thyroid
calcitonin functions
dec bone resorption of Ca2+
calcitonin regulation
inc serum Ca2+ > inc calcitonin
PTH originating cells
chief cells of parathyroid
PTH function/effects
increases:
bone resorption of Ca2+
Ki RA of Ca in DCT
Decreases: RA of Ph in PCT
PTH patho
↑ primary hyperparathyroid, tertiary hyperparathyroid, PTHrP-secreting tumor
↓ hypoparathyroidism, dec serum Ca, vit D def
PTH reg
inc PTH = inc Ca2+, PO4^3, Mg2+
dec PTH = dec Mg2+
insulin function/effects
binds insulin receptors to induce glucose uptake into insulin deep tissues
insuilin patho
↑ insulinoma
↓ type I DM, type II DM, LADA
insulin reg
glucose: glc enters B cells > inc ATP > closes K channels to depolarize mmebrane > VGCa open and Ca rushes in to stimulate insulin exocytosis
glucagon originating cell
pancreatic A cells
glucagon function/effects
glycogenolysis
gluconeogenesis
lipolysis
ketone production
glucagon patho
↑ glucagonoma
glucagon reg
secreted due to hypoglycemia, inhibited by insulin, hyperglycemia, SS
somatostatin originating cells
Delta cells of pancreas
somatostatin function/effects
dec GH and TSH
amide hormones
epi/norepi
thyroid hormones
peptide hormones
insulin
parathyroid hormone
calcitonin
hypothalmic and pituitary hormones
steroid hormones
pregnelone cortisol DHEA/testosterone estrogens progesterone testosterone vit D
pineal gland cells
lobular parenchyma: pinealocytes (produce/secrete melatonin) astrocytes perivascular phagocytes pineal neurons peptidergic neuron like cells
pineal gland location
between 2 brain hemoispheres near back of midbrain, between 2 sup colliculi, behind 3rd ventricle in pineal recess
pineal gland structure
small reddish gray pinecone shape with pineal stalk; increases size with cold. no blood brain barrier
pineal gland function
melatonin secretion
reg of pituitary (dec FSH/LH)
drug metabolism
reg bone metabolism
central innervation for pineal gland
pineal stalk
neurons from where innervate pineal gland
trigeminal ganglion
ant pituitary embryologic development
rathkes pouch (oral ectoderm)
ant pituitary location
vascularly connected to hyopthalamus via hypophyseal portal system
ant pituitary function/control
all 6 hormones are peptides, all but GH activate target cells via cAMP messenger system, all but two aer tropic hormones
post pituitary embryological
derived from outpocketing of oral mucosa; neuroectoderm
post pituitary structure
neural tissue that secretes neurohormones
ant pituitary structure
glandular tissue
post pituitary function/control
stores and secrete OT and ADH from hypothalamus
ant pituitary embryologic development
rathkes pouch (oral ectoderm)
ant pituitary location
vascularly connected to hyopthalamus via hypophyseal portal system
ant pituitary function/control
all 6 hormones are peptides, all but GH activate target cells via cAMP messenger system, all but two aer tropic hormones
post pituitary embryological
derived from outpocketing of oral mucosa; neuroectoderm
post pituitary structure
neural tissue that secretes neurohormones
ant pituitary structure
glandular tissue
post pituitary function/control
stores and secrete OT and ADH from hypothalamus
hypothalamus location
in brain, connected to pituitary (hypophysis) via stalk called infundibulum
hypothalamus organ type
neuroendocrine
adrenal medulla embryologic
neural crest cells
adrenal cortex embryologic
embryonic mesoderm
pineal gland sympathetic innervation
sup cervical ganglion
pineal gland parasymp innvervation
pterygopalatine and otic ganglia
pineal gland circulatory pathway
blood from choroidal branches of post cerebral; profuse blood flow; NO BLOOD BRAIN BARRIER in capillaries
thyroid innervation
sup laryngeal nerve
recurrent laryngeal nerve
parathyroid embryologic
arise from 3rd and 4th branchial pouches
parathyroid cells
chief cell: predominant epithelial cell, clear cytoplasm
oxyphil cell: eosinophilic granular cytoplasm
IGF-1 organ
liver
cortisol function/effects
↑ appetite, BP, insulin resistance, gluconeogenesis, lipolysis, proteolysis
↓ fibroblast activity, inflammation, immune responses, bone formation, blocks IL2 production
ghrelin function
stim hunger
leptin function
satiety hormone
aldosterone organ/cells
adrenal cortex, zona glomerulosa
cortisol organ/cells
adrenal cortex, zona fasiculata
DHEA organ/cells
adrenal cortex, zona reticularies
epinephrine/norepi where its made
adrenal medulla, chromaffin cells
cortisol function/effects
↑ appetite, BP, insulin resistance, gluconeogenesis, lipolysis, proteolysis
↓ fibroblast activity, inflammation, immune responses, bone formation, blocks IL2 production
explain the biochem/endocrine function of 5 reductase
converts testosterone into DHT
CKK organ
small intestine
ANP organ
heart
thymopoietin organ
thymus
explain the biochem/endocrine function of cholesterol
cholesterol desmolase > pregnenolone > 17ahydroxylase > 17OHpregnenolone > 17anhydroxylase > DHEA
explain the biochem/endocrine function of 17a hydroxylase
converts pregnenolone into DHEA and progesterone into androstenedione
explain the biochem/endocrine function of aromatase
converts androstenedione into estrone and testosterone into estradiol
explain the biochem/endocrine function of 21 hydroxylase and 11b hydroxylase
convert progesterone > 11deoxycorticosteone > corticosterone (to eventually be made into aldosterone)
regulation of calcium in the body
regulation via PTH > stim osteoclasts to resorb Ca from bone, increased Ca RA in DCT and inc production of vit D in kidney (decreases renal RA of phosphate)
vit D promotes RA of Ca from bone and small int
calcitonin inhibits osteoclasts, dec absorption of Ca from bone
major regulation of PTH
ionized/free Ca2+ > chanegs in pH alter PTH secretion
hyperadrenalism pathologies
cushing syndrome
(primary hyperaldosteronism) - conn syndrome
congenital adrenal hyperplasia
vit D conversion
D2 (plants/fungi/yeast) and D3 (sun/fish/plants) > 25OHD in liver and 125 OHD in kidney
skin converts 7-DH cholesterol into D3 (cholecalciferol)
cushing syndrome sx
wt gain, HTN, MOON FACE, abdominal STRIAE, truncal obesity, BUFFALO HUMP, skin changes, osteoporosis, hyperglycermia/IR, amenorrhea, immunosuppresion
hyperaldosteronism/Conn syndrome etiology
aldosterone-producing adenomas, bilateral adrenal hyperplasia
hyperaldosteronism/Conn syndrome RF
inc aldosterone, dec renin
secondary: inc aldosterone AND inc renin
T3 and T4 are made from
coupled tyrosine molecules
cushing syndrome etiology
inc cortisol
cushing syndrome sx
wt gain, HTN, MOON FACE, abdominal STRIAE, truncal obesity, BUFFALO HUMP, skin changes, osteoporosis, hyperglycermia/IR, amenorrhea, immunosuppresion
primary hyperaldosteronism/Conn syndrome etiology
inc aldosterone from adrenal adenoma or BL adrenal hyperplasia, dec renin
secondary: inc aldosterone and inc renin; renovascular HTN, renin tumors, edema from cirrhosis, HF, nephrotic
primary hyperaldosteronism/Conn syndrome RF
30-50
primary hyperaldosteronism/Conn syndrome sx
HTN, dec or normal K, metabolic alkalosis, no edema
hyperparathyroidism sx
stones: calcium oxalate
bones: osteoporosis, osteitis fibrosa cystica, bone pain with inc alk phos
groans: stomach pain, peptic ulcers
moans: depression
thrones: polyuria
congenital adrenal hyperplasia clinical characteristics
17ahydroxylase: inc mineralcorticoids and BP, dec sex hormones and K. XY ambiguous with undescended testes, XX without secondary development
21hydroxylase: dec mineralcorticoids and BP, inc sex hormones and K/renin. most common, infancy or childhood. XX viralization
11Bhydroxylase: dec aldosterone, inc 11DO corticosterone and BP, inc sex hormones, dec K and renin. XX viralization
primary hyperparathyroidism etiology
most common primary endocrine disorder after DM
adenoma (80%)
diffuse hyperplasia (10-15%)
carcinoma (1-2%)
primary hyperparathyroidism RF
F > 50
primary hyperparathyroidism complications
muscle atrophy
acute pancreatitis
primary hyperparathyroidism sx
stones: calcium oxalate
bones: osteoporosis, osteitis fibrosa cystica, bone pain with inc alk phos
groans: stomach pain, peptic ulcers
moans: depression
thrones: polyuria
secondary hyperparathyroidism etiology
caused by any condition caused by chronically diminished levels of Ca2+
most commonly from chronic renal failure/insufficiency, inadequate vit D/calcium, steatorrhea
hyperpituitarism pathologies
acromegaly
gigantism
acromegaly etiology
excess GH in adults, inc insulin like GF 1
typically caused by pituitary adenoma
acromegaly complications
inc risk for colorectal polyps + cancer
dilated cardiomyopathy
acromegaly sx
large tongue with deep furrows, deep voice, large hands/feet, frontal bossing, diaphoresis, insulin resistance, HTN
gigantism etiology
excess GH in kids
pituitary adenoma
mccune albright syndrome
gigantism complications
HF most common cause of death (inc size of heart)
gigantism sx
rapid/excessive growth of long bones (tibia, humerus)
soft tissue/organ growth
graves disease etiology
autoimmune
graves disease RF
F 40-60
genetics
stress, tobacco, infxn, iodine exposure
postpartum
graves disease sx
uniform soft supple goiter
inflammatory endocrine pathologies
hashimoto thyroiditis
granulomatous subacute thyroiditis
diabetes insipidus sx
intense thirst and polyuria with inability to concentrate urine due to lack of ADH or failure of response to circulating ADH
dec urine SG
inc serum osmolality
endocrine vascular pathologies
postpartum pituitary necrosis (Sheehans)
infectious endocrine pathologies
infectious thyroiditis
waterhouse-friderichsen syndrome
diabetes insipidus etiology
central:
dec ADH
pituitary tumor, AI, trauma, surgery, ischemic encephalopathy, idiopathic
nephrogenic:
normal or inc ADH
hereditary, hyepr Ca, hypoK, Li, meds
diabetes insipidus sx
intense thirst and polyuria with inability to concentrate urine
dec urine SG
inc serum osmolality
hypoadrenalism pathologies
addison disease
primary acute insufficiency (waterhouse-friederichsen syndreome), secondary + tertiary adrenocortical insufficiency
addison dz etiology
chronic adrenal insufficiency due to adrenal atrophy/destruction by disease
dec gland function > dev cortisol + dec aldosterone
addison dz RF
autoimmune destruction most common in western world
TB most common in develping world
hypoadrenalism/adrenal insufficiency complications
may present with shock in acute adrenal crisis
- pain in lower back, abdomen, legs
- fever/chills
- severe vomiting + diarrhea
- hypotension
- LOC
addison dz sx
skin hyperpigmentation
hyperkalemia
hypotension
metabolic acidosis
primary acute adrenal insufficiency etiology
sudden onset (e.g due to massive hemorrhage)
waterhouse-friderichsen syndrome: due to adrenal hemorrhage associated with septicemia (usu neisseria meningitidis), DIC, endotoxic shock
primary acute adrenal insufficiency sx
WFS: petechial rash
secondary acute adrenocortical insufficiency etiology
seen with dec pituitary ACTH production
tertiary acute adrenocortical insufficiency etiology
seen in pts with chornic exogenous steroid use, precipitated by abrupt withdrawl
tertiary acute adrenocortical insufficiency RF
drugs
secondary acute adrenocortical insufficiency etiology sx
NO skin hyperpigmentation
NO hyperkalemia
hypoparathyroidism etiology
accidental surgical excision, AI desctruction, DiGeorge syndrome
hypoparathyroidism sx
CATS go numb
tetany, hypocalcemia, hyperphosphatemia
Chvostek sign: contraction of facial muscles
Trousseau sign: carpal spasm
hypopituitarism pathologies
empty sella syndrome
hypothalmic lesions
sheehan syndrome
hypothyroidism etiology
nutrient deficiency (iodine or selenium)
hypothyroidism sx
wt gain, cold intolerance, constipation, coarse skin, depression, poor memory, heavy menses, jaundice
inc TSH, low fT4, normal Ab
(iodine deficient goiter)
sheehan syndrome etiology
ischemic infarct of pituitary after postpartum bleeding
hasimoto thyroiditis RF
genetics, environmental toxins, chronic infxns, drugs, meds, smoking, diet (alcohol, goitrogens, gluten, iodine), age, pregnancy, stress, sex hormones
hypothyroidism (iodine deficient goiter) etiology
nutrient deficiency (iodine or selenium)
hypothyroidism sx
wt gain, cold intolerance, constipation, coarse skin, depression, poor memory, heavy menses, jaundice
inc TSH, low fT4, normal Ab
hasimoto thyroiditis etiology
Th1 CD4 cells secrete cytokines that upregulate CD8 cells which cause destruction in thyroid > th2 CD4 > upregulation B cells > antibodies
OR
autoantibodies to thyroid (TPOAb, TgAb)
hasimoto thyroiditis complications
most common cause of hypothyroid in western world
myxedema coma: weakness, stupor, hypothermia, hypoventilation, hypoglycemia, hyponatremia, shock, death
increased CVD risk hyperthyroidism thyroid enlargment primary B cell lymphoma papillary thyroid cancer
hasimoto thyroiditis sx
Weight gain, Cold intolerance, Constipation, Coarse, thin, scaly skin, Non-pitting edema, Dull, thin nails, Loss of ⅓ of eyebrow, dry brittle coarse hair, Decreased sweating, Carpal tunnel syndrome, Heavy menses
dysphagia (esophagus compressed by goiter)
uniform, nontender, locally nodular, irregular goiter
celiac disease
inc TSH, dec fT4, inc TPOAb, TgAB
hurthle cells
granulomatous subacute thyroiditis etiology
(de Quervain)
self limited diseas eoften followinga flu like illness
granulomatous subacute thyroiditis sx
inc ESR
jaw pain
tender thyroid
diabetes type 1 etiology
autoimmune destruction of beta islet cells of pancreas > absolute insulin deficiency
islets infiltrated by t cells + inflammation and destruction ensures > islets develop fibrosis + atrophy
DM1 RF
<19
DM1 sx
polydipsia polyuria polyphagia wt loss blurry vision
DM1 complications
diabetic ketoacidosis; rapid breathig, fruit like odor breath, disorientation, sudden coma
DM2 etiology
hyperglycemia with insulin resistance and impaired insulin secretion
hyperinsulinemia > insulin ressitance > exhausted pancreas > absolute insulin deficiency
DM2 RF
obesity, inflammation, aging, genetics, hyperlipidemia, HTN, metabolic syndrome
DM2 sx
polydipsia, polyphagia, polyuria, wt loss
suspect in any overweight pt with genetic predisposition
what is a thyroglossal duct cyst
anterior midline neck mass that moves with swallowing or protrusion of tongue (vs persistent cervical sinus leading to branchial cleft cyst in lateral neck)
adrenal neoplasm pathologies
neuroblastoma
pancreas neoplasm pathologies
insulinoma
parathyroid neoplasm pathologies
adenomas
pituitary neoplasm pathologies
adenoma prolactinoma GH adenoma ACTH adenoma craniopharyngioma non-functioning tumor
thyroid neoplasm pathologies
adenoma follicular carcinoma papillary carcinoma medullary carcinoma euthyroid goiter
other endocrine neoplasms
multipel endocrine neoplasia
types 1 + 2 pheochromocytoma
insulinoma etiology
derived from pancreatic beta cells > secrete insulin
most common neuroendocrine tumor (2nd is gastrinoma)
10% associated with MEN1
neuroblastoma RF
most common tumor of adrenal medulla in kids < 4
neuroblastoma sx
abdominal distention with firm, irregular mass that can cross midline
insulinoma complications
mets 5-30%
insulinoma sx
hypoglycemia (whipple triad: hypoglycemia, sx of hypoG, resolution of sx after glc levels normalize)
dec blood glucose
inc insulin
inc proinsulin
inc c peptide
parathyroid adenoma etiology
MEN1
infectious thyroiditis etiology
rare; bacterial, fungal, parasite
staph aureus
waterhouse-friderichsen syndrome etiology
acute primary adrenal insufficiency due to adrenal hemorrhage
associated with septicemia from neisseria meningitidis, DIC, endotoxic shock
most common cause of hypopituitarism
macroadenoma
most common pituitary neoplasm
prolactinoma
prolactinomas sx
females: galactorrhea, amenorrhea/oligomenorrhea, infertility, dec libido, low estrogen > menopausal sx, osteoporosis
males: dec libido, impotence (more common sx in men since dx is often later)
pituitary adeoma/macroadenoma general sx
mass effect:
visual field defects (bitemporal hemianopsia)
inc intracranial pressure (headache, N/V)
depression, anxiety
craniopharyngioma complications
pituitary tumor; causes secondary (central) hypothyroidism, dec TSH, dec fT4
ACTH adenoma clinical characteristics
increased ACTH > increased cortisol + other adrenal secretions
cushings syndrome obesity, central fat, moon face hirsuitism excess hair purple striae, easy bruising superficial fungal infections osteopenia, osteoporosis diabetes, HTN menstrual/mental abnormalities
what is a nonfunctional tumor
one that does not have sx related to secreting excessive hormones, but may secrete other peptides
toxic thyroid adenoma etiology
low iodine
toxic thyroid adenoma sx
solitary palpable hot nodule
dec TSH, inc fT4/T3, inc RAIU uptake
pheochromocytoma etiology
most common neoplasm of adrenal medulla (rare)
secrete excess catecholamines, often cause severe HTN
rule of 10% extraadrenal bilateral malignant arise in kids calcify occur with other endocrine neoplasms (MENS)
pheochromocytoma complications
sever HTN
may induce stroke, MI, fatal cardiac arrhythmia
pheochromocytoma sx
palpitations tachycardia headache profuse sweating N/V abdominal and chest pain insomnia
infectious thyroiditis lab values
inc TSH, low fT4
pathway of synthesis of adrenal steroids: progesterone and 17oh pregnenolone
cholesterol > pregnenolone (ZG) >:
- (17ahydroxylase) > 17OH pregnenolone (ZF)
- progesterone (ZG) > (17ahydroxylase) > 17OH progesterone
pathway of synthesis of adrenal steroids: aldosterone
progesterone (ZG) > (21hydrozylase) > 11deoxycorticosterone (ZG)> (11bhydroxylase) > corticosterone (ZG) > aldosterone (ZG)
pathway of synthesis of adrenal steroids: cortisone
17 hydroxypregnenolone (ZF) > 17hydroxyprogesterone (ZF) > (21 hydroxylase) > 11 deoxycortisol (ZF) > (11bhydroxylase) > cortisol (ZF) > cortisone (ZF)
pathway of synthesis of adrenal steroids: estradiol, testosterone, DHEA
- 17 hydroxypregnenolone (ZF) > 17hydroxyprogesterone (ZF) > androstenedione (ZR) > testosterone (ZR) + estrone (PT) > estradiol (PT)
- 17 hydroxypregnenolone (ZF) > DHEA (ZR):
> DHEA-s (ZR)
> androstenedione (ZR) > testosterone (ZR) + estrone (PT) > estradiol (PT)