Endocrine Flashcards
Thyroid diverticulum arises from the
Floor of primitive pharynx and descend into neck
Thyroid connected to tongue via
Thyroglossal duct – persistence –> thyroglossal duct cyst or pyramidal lobe of thyroid
Ectopic thyroid tissue often found on
Tongue (removal can –> hypothyroidism if only thyroid tissue)
Persistent cervical sinus
Branchial cleft cyst in lateral neck
Thyroglossal duct cyst
Midline in neck that moves w/ swallowing
Derivation of thyroid
Endoderm
Adrenal cortex derivation
Mesoderm
Adrenal medulla derivation
Neural crease
Zona Glomerulosa
Outer layer – aldosterone (mineralocorticodid), regulated by Ang II
Zona fasciculata
Middle layer – cortisol (glucocorticoid), reg by ACTH, CRH
Zona reticulata
Inner layer – androgens – DHEA, reg by ACTH, CRH
Medulla
Chromafin cells regulated by preganglionic sympathetic fibers –> release catecholamines NE/E
Anterior pituitary aka
Adenohypophysis
Anterior pituitary secretes
FSH, LH, ACTH, TSH, PRL, GH, MSH (FLAT PiG)
Derivation of anterior pituitary
Rathke’s pouch (oral ectoderm)
Alpha subunit is common to
TSH, LH, FSH, hCG
B subunit
Determines hormone specificity
Acidophils produce
GH, PRL
Basophiles produce
FSH, LH, ACTH, TSH
B-FLAT
Posterior pituitary hormones
ADH, oxytocin
Post pituitary hormone synthesis
Synthesis is in hypothalamus in supraoptic/paraventricular nuclei –> post. pituitary via neurophysins
Post. pituitary derivation
Neuroectoderm
Alpha cells of pancreas make
Glucagon (peripheral in islet)
Beta cells of pancreas make
Insulin (central in islet)
Delta cells of pancreas make
Somatostatin (interspersed in islet)
Insulin synthesis
Preproinsulin from RER –> cleave presignal to proinsulin (stored in secretory granules) –> cleave proinsulin –> exocytose equal amounts of insulin and C peptide
Insulin receptors are…
Tyrosine kinase –> PIP3 and RAS/MAP
PIP3 pathway in response to insulin results in
GLUT4 vesicles translocated to membrane and glycogen, lipid and protein synthesis
RAS/MAP pathway leads to
Cell growth, DNA synthesis
Effects of insulin
Anabolic -- Increased glc transport in skeletal m/adipose tissue Increased glycogen synth/storage Increased trig synthesis Increased Na retention (kidneys) Increased protein synth (mms) Increased cellular uptake of K and amino acids Less glucagon release Less lipolysis in adipose tissue
Does insulin cross placenta?
No
Insulin dependent glucose transporters and location
GLUT4 – adipose tissue, striated muscle (increased by exercist)
Insulin independent glucose transporters and location
GLUT1: RBCS, brain, cornea, placenta
GLUT2 (bidirectional): B islet cells, liver, kidney, SI
GLUT3: brain, placenta
GLUT5 (fructose): spermatocytes, GI tract
Insulin independent glucose uptake in BRICK L
Brain, RBCs, Intestine, Cornea, Kidney, LIver
Insulin release related to sympathetic stimulation
Decreased by alpha2
Increased by beta2
Process of excreting insulin in response to glucose
Glucose enters B cells –> more ATP made from metabolism of glc –> closes K channels (target of SUs) –> depolarization –> voltage gated Ca channels open –> Ca influx –> insulin exocytosis
Glucagon function
Glycogenolysis, gluconeogenesis, lipolysis, ketone prodxn – secreted in response to hypoglycemia, inhib by insulin, hyperglycemia, somatostatin
CRH –>
Increases ACTH, MSH, B-endorphin, lower in chronic exogenous steroid use
Dopamine–>
Less PRL, TSH (dopamine antagonists –> galactorrhea due to hyper prolactinemia
GHRH–>
Increased GH
Tesamorelin
GH analog used to tx HIV assc lipodystrophy
GnRH–>
Incereased FSH, LH –> suppressed by hyperprolactinemia
Tonic GnRH–>suppresion of HPG axis
Pulsatile GnRH –>puberty, fertility
PRL—>
Less GnRH
Pituitary prolactinoma–>
Amenorrhea, osteoporosis, hypogonadism, galactorrhea via suppression of GnRH
Somatostatin–>
Decreases GH, TSH –> analogs can treat acromegaly (octreotide)
TRH–>
Increased TSH, PRL; increased TRH in 1o/2o hypothyroidism (trying to compensate) may increase prolactin secretion –> galactorrhea
PRL fxn–>
Stimulates milk prodxn in breast, inhib ovulation in females/spermatogenesis in males by inhib of GnRH synth/release (increase assc w/ decreased libido)
Dopamine and PRL
Dopamine inhibits PRL secretion via tuberoinfundibular pathway of hypothalamus
Dopamine agonists
Bromocriptine –> inhib PRL secretion –> tx of prolactinoma
Dopamine antagonists and estrogens–>
stimulate PRL secretion
GH aka
Somatotropin
Fxn of GH
Stimulates linear growth/muscle mass via action of IGF-1 from liver, increases insulin resistance (diabetogenic)
IGF-1 aka
Somatomedin C
GH regulation
GHRH –> pulsatile release of GH esp during exercise, deep sleep, puberty, hypoglycemia
Inhibition of secretion by glc, somatostatin (negative feedback on somatomedin)
Excess GH
Gigantism in children, acromegaly in adults – tx w/ stomatostatin analogs (octreotide) or surgery
Ghrelin–>
Hunger stimulation (orexigenic) and GH release
Ghrelin produced by
Stomach
Ghrelin increased by
Sleep deprivation or Prader Willi
Leptin–>
Satiety
Leptin made by
Adipose tissue
Leptin mutations–>
Congenital obesity
Leptin reduced by
Sleep deprivation, starvation
Endocannabinoids
Act at cannabinoid receptors in hypothalamus and nuc accumbens –> homeostatic/hedonic control of food intake –> increased apptite
ADH synthesis
Hypothalamus (supraoptic nuclei)
ADH fxn
Regulates serum osmo via V2 and BP via V1
Decreases serum osmo, increases urine osmo
How ADH works
Regulates aquaporin channel insertion in principle cells of collecting duct
When is ADH lower?
Central DI (can be normal or high in nephrogenic DI)
Cause of nephrogenic DI
Mutatio in V2
Desmopressin acetate
ADH analog – tx of central DI and nocturnal enuresis
Regulation of ADH
Osmoreceptors in thalamus, hypovolemia
17alpha hydroxylase def – effect on mineralocorticoids, cortisol, sex hormones, BP, K+, assc labs, presentation
Mineralocorticoids: increased Cortisol: decreased Sex hormones: decreased BP: increased K+: decreased Labs: low androstendione Presentation: XY-->ambiguous, undescended testes XX-->lacks 2o sexual development
21 hydroxylase def – effect on mineralocorticoids, cortisol, sex hormones, BP, K+, assc labs, presentation
Most common Mineralocorticoids: Decreased Cortisol: Decreased Sex hormones: increased BP: low K+: High Labs: High renin, high 17-hydroxy progesterone Presentation: Salt wasting in infancy, precocious puberty in childhood, XX: virilization
11 B hydroxylase def – effect on mineralocorticoids, cortisol, sex hormones, BP, K+, assc labs, presentation
Mineralocorticoids: Decreased aldo, but high 11-deoxycorticosteron (-->increase in BP) Cortisol: Decreased Sex hormones: Increased BP: Increased K+: Low Labs: Low renin activity Presentation: XX: virlization
Common features of multipl CAH
Enlargement of adrenal (increased ACTH), skin hyperpigmentation
Cortisol binds to
Cortisol binding globulin
Cortisol fxns
Increased appetite
Increase BP
- Upreg of alpha 1 on arterioles –> increased sens to NE/Epi
-High conc. binds to mineralocorticoid (aldo) receptors
Increase insulin resistance
Increase gluconeogenesis, lipolysis, proteolysis (less glc utilization)
Decrease fibroblast activity (–>poor wound healing, decreased collagen synth, increase in striae)
Decreased inflam/immuni response
- Inhib prdxn of leukotriences/PGs
- Inhib WBC adhesion (–>neutrophilia)
- Blocks histamine release from mast cells
- Eosinopenia, lymphopenia
- Blocks IL-2 prodxn
Less bone formation (decreases activity of osteoblasts)
A BIG/FIB
Regulation of cortisol
CRH–>ACTH–>cortisol prodxn –> excess downregs CRH, ACTH, and cortisol
BUT chronic stress –>prolonged secretion of cortisol
Calcium in plasma forms
Ionized/free>albumin>anions
Calcium in plasma change in binding…
Increased pH –> more affinity of albumin for Ca (increased neg charge) –> binding of Ca –> hypocalcemia (cramps, pain, paresthesias, carpopedal spasm)
Regulation of PTH
Ionized/free Ca
Vit D action
Increased absorption of dietary Ca and PO4, enhances bone mineralization
Vit D reg
Increased by PTH, low Ca and low PO4
Deficiency of vit D
Ricket in kids
Osteomalacia in adults
Due to malabsorption, low sunlight, poor diet, CKD
24 hydroxylase and Vit D
Makes 24,25 OH2 D3 – inactive
PTH action
Increased Ca/PO4 reabsorption from bone
Increased kidney reabsorption of Ca in DCT
Decreased reabsorption of PO4 in PCT
Increased dihydroxy vit D by stim of kidney 1alpha hydroxylase in prox tubule
NET LOSS OF serum PO4, increase in urine cAMP, increase in serum Ca
PTH secreted by
Chief cells of parathyroid
PTH action on bone –
Stimulates RANKL on osteoblasts/osteocytes
–> binds RANK on osteoclasts to stimulate them to resorb bone
Intermitten PTH release –>
Bone formation
Malignancies of PTHrP
SCC of lung, RCC
Regulation of PTH
Secretion sim: low Ca, high PO4, low Mg
Secretion inhib: REALLY low Mg
Causes of low Mg
Diarrhea, aminoglycosides, diuretics, EtOH abuse
What cells secrete calcitonin?
Parafollicular of thyroid
Action of calcitonin
Decreases bone resorption of Ca (stim by increased Ca); not really significant in normal Ca homeostasis
Thyroid hormone is produced in
Follicles of thyroid (t3 conversion in tissues mostly)
Fxn of thyroid hormones
Bone growth (GH synergism)
CNS maturation
Increases B1 receptors in heart (Increases CO, HR, SV, contractility)
Increased BMR by increase of Na/K ATPase activity –>more O2 consumption, RR, body temp
Increase in glycogenolysis, gluconeogenesis, lipolysis
(4 B’s – brain mat, bone growth, beta adrenergic, BMR)
Reg of thyroid hormone
TRH from hypothalamus–>TSH from ant pituitary–>stimulation of follicular cells (also via TSI in graves)
Negative feedback of T3/T4 on hypothalamus and ant pituitary
Wolff Chaikoff effect
Excess iodine –> temporary inhib of TPO –> less iodine organification –> less T3/4 prodxn
Thyroid hormone synthesis
Iodine/Na transporter into thyroid foll cell–>goes into colloid–>I gets oxidized to I2 via TPO –> organification of I2+TG by TPO resulting in –> MITs and DITs –> TPO causes coupling so some DIT/MITs combine to make T3/T4 (still attached to TG) –> endocytosed back into follicular cell–> proteases cleave thryoid hormones from TG (gets recycled) –> released into circ (5’ deiodinase catalyzes T4–>T3 in tissues
Cases of low TBG
Hepatic failure, steroids
Cases of high TBG
Pregnancy, OCP (increased by estrogen!)
Action of glucocorticoids on thyroid hormones
Inhibition of peripheral T4–>T3
cAMP signalling pathway hormones
FSH, LH, ACTH, TSH, CRH, h-CG, ADH (V2), MSH, PTH, calcitonin, GHRH, glucagon, histamine (H2)
FLAT ChAMP +calcitonin, GHRH, glucagon, histmine
cGMP signalling pathway hormones
BNP, ANP, EDRF (NO)
BAD GraMPa (vasodilators)
IP3 signalling pathway hormones
GnRH, Oxytocin, ADH (V1), TRH, Histamine (H1), Ang II, Gastrin
GOAT HAG
Intracellular receptor hormones
Prog, E2, Testosterone, Cortisol, Aldosterone, T3/T4, Vit D
PET CAT on TV
Receptor TK homones
Insulin, IGF-1, FGF, PDGF, EGF (MapK pathway, growth factors)
Nonreceptor TK hormones
Prolactin, Immunomodulators (cytokines, IL2, IL6, IFN), GH, G-CSF, EPO, TPO
(Jak-STAT, acidophils and cytokines)
PIGGlET
Effect of SHBG in men
Increased –> more bound Test –> lowers free T –> gynecomastia
Effect of SHBG in women
Low –> more free T –> hirsuitism
Effect of OCPs/pregnancy on SHBG–>
Increases it
Causes of Cushing syndrome
Increased cortisol:
- Exogenous corticosteroids
- 1o adrenal adenoma, hyperplasia, carcinoma
- ACTH secreting pituitary adenoma and paraneoplastic ACTH secretion
Exogenous corticosteroids labs
Low ACTH, bilat adrenal atrophy – most common cause
1o adrenal adenoma, hyperplasia, carcinoma labs
Low ACTH, atrophy of uninvolved gland, can present w/ pseudohyperaldosteroneism via stim of aldor
ACTH secreting pituitary adenoma and paraneoplastic ACTH secretion labs
High ACTH, bilat adrenal hyperplasia
Majority of endogenous ACTH cushings syndrome
Cushings disease (ACTH pituitary adenoma)
Findings in cushings syndrome
HTN, wt gain, moon facies, abdominal striae, truncal obesity, buffalo hump, skin changes (thinning, striae), osteoporosis, hyperglycemia (due to ins resistance), amenorrhea, immunosuppression
Screening algorithm for Cushings
- ACTH measured via 24 hr free urine, late night salivary, inadequate suppression via 1 mg dexamethasone
IF SUPPRESSED – ACTH indepented like exogenous or adrenal tumor
IF ELEVATED – ACTH dependent - Do CRH stimulation test or 3. High dose dex
Ectopic secretion – CRH doesn’t affect ACTH and no suppression w/ high dose dex (do CT of chest/abdomen/pelvis)
Pituitary adenoma – CRH will increase ACTH and cortisol, high dose dex will suppress (MRI of pituitary)
Adrenal insufficiency sx
Weakness, fatigue, orthostatic hypotension, muscle aches, wt loss, GI disturbances, sugar/salt cravings
Tx of adrenal insufficiency
Supplement glucocorticoids/mineralocorticoids
Diagnosis of adrenal insufficiency
Measure serum lytes, cortisol, ACTH; metyrapone stim – blocks last step of cortisol synth (11-deoxycort–>cort)
Diagnosis results in 1o adrenal insufficiency
Low cort, high ACTH, metyrapone –> increased ACTH but low 11-deoxycortisol
Diagnosis results in 2o/3o adrenal insufficiency
Low cort, low ACTH, metyrapone –> low ACTH and 11 deoxycortisol
1o adrenal insufficiency
Def of aldo and cortisol due to loss of gland fxn –> hypotension (hyponatremic volume contraction), hyperkalemia, metabolic acidosis, skin/mucosal hyperpigmentation (increased MSH from ACTH prodxn)
Acute 1o adrenal insufficency
Suden onset (e.g. massive hemorrhage) –> shock
Chronic 1o adrenal insufficiency aka
Addison disease
Chronic 1o adrenal insuff due to
Adrenal atrophy/destruction by diease (autoimmune in west, TB in developing world)
Associated with 1o adrenal insuff
Autoimmune polyglandular syndromes
Waterhouse-Friedrichsen syndrome
Acute adrenal insuff due to adrenal hemorrhage assoc w septicemia (N. gonorrhea), DIC, endotoxic shock
2o adrenal insuff
Decreased pituitary ACTH prodxn – no skin pigmentation, no hyperkalemia (aldo is fine bc of intact RAAS)
3o adrenal insuff
Chronic exogenous steroid use – precipitated by abrupt w/drawal (No effect on aldo synth)
Hyperaldosteronism –
Increased aldo –> HTN, decrease/normal K
1o hyperaldosteronism
Adrenal adenoma (Conn syndrome) or bilateral adrenal hyperplasia –> high aldo and low renin
2o hyper aldo seen in…
Pt w/ renovascular HTN, JG cell tumors that make renin, edema
Neuroendocrine tumors
Originate from Kulchitsky and enterochromaffin like cells – thyroid medullary carcinoma, lung small call carcinoma, islet cell tumor of pancreas, pheochromocytoma
Neuroendocrine tumors contain and secrete
Contain – APUD
Secrete: 5HIAAA, NSE, chromogranin A
Neuroblastoma demographics..
Most common adrenal medulla tumor in children under 4
Origin of neuroblastoma
Neural crest
Neuroblastoma location
Anywhere in sympathetic chain
Presentation of neuroblastoma
Abdominal distension, firm/irregular mass (can cross midline unlike Wilms), opsoclonus-myoclonus syndrome (dancing eyes, dancing feet)
Lab tests in neuroblastoma
Increased HVA and VMA in urine
Histology of neuroblastoma
Homer Wright rosettes (also in medulloblastoma), NSE and Bombesin +
Genetics of neuroblastoma
Overexpression of N-myc
Classification of neuroblastoma
APUD tumor
Pheochromocytoma demographics
Most common tumor of adrenal medulla in adults
Derivation of pheochromocytoma
Chromaffin cells (from neural crest)
Germline mutations associated w/ pheochromocytoma
NF1, VHL, RET (MEN2A/B)
Rule of 10s
In pheochromocytoma 10% malignant 10% bilat 10% extra adrenal (bladder wall, organ of Zuckerkandl) 10% calcify 10% kids
Sx of pheochromocytoma
Due to secretion of Epi. NE, and Dop –> episodic HTN, headache, perspiration, palpitations, pallor in spells (relapse/remit)
Labs in pheochromocytoma
Increased catecholamines and metanephrines in urine/plasma
Tx of pheochromocytoma
Irreversible alpha ant – prevent hypertensive crisis (phenoxybenzamine) followed by B blockers and then resection
Hair in hypothyroid
Coarse brittle
Hair in hyperthroid
Fine
Myopathy in hyper vs hypothyroid
Both proximal, but hypothyroid can have low CK and hyper has NL CK
Causes of smooth/diffuse goiter
Graves, Hashimoto, Iodine def, TSH secreting pit adenoma
Causes of nodular goiter
Toxic multinodular goiter
Thyroid adenoma
Thyroid cancer
Thyroid cyst
Cholesterol in hypo vs hyperthyroid
Hypercholesterolemia (decreased LDLr expression) in hypo
Hypocholesterolemia (increased LDLr expression) in hyper
Myxedema in hypo vs hyperthyroid
Hypo – facial/periorbital
Hyper – pretibial
Hashimoto thyroiditis abs
Anti TPO or anti TG
Clinical course of hashimotos
Early hyperthyroid (follicular rupture) –> hypothyroid
Histology of hashimotos
Hurthle cell change, lymphoid aggregates w/ germinal centers
Hashimoto presentation
Moderately enlarged nontender thyroid
Congenital hypothryoidism causes
Maternal hypothyroid, thyroid agenesis, iodine def, dyshormonogenetic goiter
Congenital hypothyroidism findings
Pot bellied, Pale, Puffy faces w/ Protruding umbilicus, Protuberant tongue, Poor brain dev (6Ps)
Subacute granulomaous thyroiditis (de Quervain) clinical course
Self limited after flu like illness (e.g. viral infxn) hyperthyroid–>hypothyroid
Histology of de Quervain thyroiditis
Granulomatous inflam
Findings in de Quervain thyroiditis
Increased ESR, jaw pain, TENDER thyroid
Subacute lymphocytic thyroiditis
Autoimmune rxn in young/middle aged women post partum – mild enlargement of thyroid w/ patchy destruction of follicles; transient mild thyrotoxicosis–>hypothyroid
PAINLESS
Riedel thyroiditis
Thyroid replaced by fibrous tissue w/ inflamm inflitrate, can extend to local structures (trachea/esophagus); 1/3 are hypothyroiid
Assc w/ IgG4 systemic disease (autoimmune pancreatitis, retroperitoneal fibrosis, noninfectionaortitis)
Fixed, hard, painless goiter
Graves disease abs
TSI – stimulates TSHr on thyroid and dermal fibroblasts (–>pretibial myxedema)
Pathophys of exopthalmos
T cell infiltration of retroorbital space by activated T cells –> increased cytokines (TNFalpha, IFN gamma) –> fibroblasts secrete GAGs –>osmotic muscle swelling, finlamm, increased adiopocytes –> exopthalmos
Graves HLA associations
HLA DR3, HLA B8
Toxic multinodular goiter
Patches of hyperfunctioning follicular cells distended w/ colloid working independent of TSH (usually TSHr mutation) –> more T3 T4 released
Thyroid storm
Untreated/undertreated hyperthyroidism + stress (infxn, trauma, etc) –> agitation, fever, delirium, fever, diarrhea, coma, tachyarrhythmia (can cause death)
Thyroid storm tx
B blockers (Propanolol), PTU, corticosteroids (Prednisone), Potassium iodide (Lugol idoine) (4Ps)
Jod-Basedow phenomenon
Thyrotoxicosis if pt w/ iodine def and partiallly autonomous thyroid tissue is made iodine replete (opp of Wolff Chaikoff)
Thyroid adenoma
Benign solitary growth of thyroid, usually cold
Rarely can cause hyperthyroidism
Thyroid adenoma histology
Follicular usually – no capsular/vascular invasion (see in follicular carcinoma)
Thyroid cancer diagnosis
Fine needle aspiration, tx is thyroidectomy
Thyroidectomy complications
Hoarseness (recurrent laryngeal n. injury), hypocalcemia (parathyroid removal), transection of recurrent/sup laryngeal n during ligation of inf thyroid a. and sup thyroid a. respectively
Papillary carcinoma incidence, prognosis
Most common, good prognosis
Papillary carcinoma histology
Empty-appearing nuc w/ central clearing (oprhan annie), psammoma bodies, nuclear grooves
Papillary carcinoma associations/genetics
RET, BRAF, childhood irradiation
Follicular carcinoma prognosis
Good
Follicular carcinoma histology
Invades thyroid capsule/vasculature, has uniform follicles
Spread of follicular carcinoma
Hematogenous!
Genetics of follicular carcinoma
RAS
Medullary carcinoma origin cells
Parafollicular C cells
Medullary carcinoma makes…
Calcitonin –> amyloid
Medullary carcinoma histology
Sheets of cells in amyloid stroma, stains w/ congo red
Mutations assoc w/ medullary carcinoma
MEN2A/2B RET
Undifferentiated/anaplastic carcinoma demographic
Older patients
Undifferentiated/anaplastic carcinoma prognosis
Poor – invades local structures
What disease is lymphoma associated w/?
Hashimoto’s
1o hypoparathyroidism causes
Surgical, resection, autoimmune, DiGeorge
hypoparathyroid findings
Hypocalcemia –> tetany, hyperphosphatemia
Chovstek sign
Tapp facial nerve –> facial mm contraction
Trousseau sign
Occlusion of brachial a w/ BP cuff –> carpal spasm
2o hypoparathyroidism causes
Vit D deficiency, low Ca intake, chronic renal failure
1o hyperparathyroidism causes
Hyperplasia, adenoma, carcinoma
PTH independent hypercalcemia
Excess Ca intake, cancer, high vit D
Pseudohypoparathyroidism 1A aka
Albright hereditary osteodystrophy
Pseudohypoparathyroidism 1A pathophys
Defective Gs protein alpha subunit–> Unresponsiveness of kidney to PTH –> hypocalcemia despite high PTH
Pseudohypoparathyroidism 1A findings
Short 4/5 digits, short stature
Pseudohypoparathyroidism 1A genetics
AD, must be inherited from mother due to imprinting
PseudoPSEUDOhypoparathyroidism
Phyical exam features like Albright’s but no end-organ PTH resistance — defect inherited from father
1o hyperparathyroidism findings
Hypercalcemia, hypercalciuria (–>kidney stones), polyuria, hypophosphatemia, high PTH, high ALP, high cAMP in urine; usually asymptomatic, but may have weakness/constipation, abdominal/flank pain (kidney stones, acute pancreatitis), depression
Osteitis fibrosa cystica
Cystic bone spaces filld w/ brown fibrous tissue made of osteoclasts and hemosiderin from hermorrhages; due to high PTH (esp 1o)
2o hyperparathyroidism findings
Hypocalcemia, hyperphosphatemia in chronic renal failure (low in other cases), high ALP, high PTH
3o hyperparathyroidism causes
Refractory (autonomous) hyperparathyroidism resulting from chronic renal disease, high Ca, really high PTH
Renal osteodystrophy
Renal disease –> 2o/3o hyperparathyroidism –> bone lesions
Familial hypocalciuric hypercalcemia
Defective Gcoupled Ca sensing receptors –> higher than normal Ca levels to suppress PTH; excessive renal Ca reuptake –> mild hypercalcemia and hypocalciuria w/ normal/increased PTH levels
Nelson syndrome
Enlargement of existing ACTH secreting pituitary adenoma after bilateral adrenalectomy for refractory Cushin disease (removal of cortisol feedback mechanism)
Nelson syndrome findings
Hyperpigmentation, headaches, bitemporal hemianopia
Tx of Nelson syndrome
Pituitary irradiation or surgical resection
Acrogmegaly cause
Usually pituitary adenoma
Acromegaly findings
Large tongue w/ deep furrows, deep voice, large hands/feet, coarsening of facial features, frontal bossing, diaphoresis, impaired glc tolerance, increased risk of colorectal polyps/cancer
Dianosis of acromegaly
High IGF-1, failure to suppress serum GH following oral glc, pituitary mass on brain MRI
Tx of acromegaly
Pituitary adenoma resection, octreotide (somatostatin analog), pegvisomant (GHr antagonist), dopamine agonists (cabergoline)
Laron dwarfism pathophysiology
Defective GHr –> less linear growth, high GH, low IGF-1
Laron dwarfism clinical features
Short height, small head circumfrence, facies w/ saddle nose and prominent forehead, delayed skeletal maturation, small genitalia
Di symptoms
Intense thirst and polyuria, no ability to concentrate urine
Central DI causes
Pituitary tumor, autoimmune, trauma, surgery, ischemic encephalopathy, idopathic
Findings in central Di
Low ADH, low urine specific grav, high serum osmo (>290), hyperosmotic volume contraction
Water deprivation in central DI
> 50% increase in urine osmo ONLY AFTER ADH analogue admin
Tx of central DI
Desmopressin acetate, hydration
Nephrogenic DI etiology
Hereditary (ADHr mutation), 2o to hypercalcemia, hypokalemia, lithium, demeclocycline (ADH ant)
Nephrogenic DI findings
Normal or increased ADH, low urine SG, high serum osmo (>290), hyperosmotic volume contraction
Water deprivation test in nephrogenic DI
Minimal change in urine osmo even after admi of ADH analog
Tx of nephrogenic DI
HCTZ, indomethacin, amiloride, hydration, dietary salt restriction, avoidance of offending agent
SIADH findings
Excessive free water retention, euvolemic hyponatremia w/ continued urinary Na excretion, urine osmo>serum osmo
SIADH body response
Water retention –> lower aldo and increase ANP?BNP –> increase Na secretion in urine –> normal ECF volume –> euvolemic hyponatremia
Result of low serum Na
Cerebral edema, seizures, correction too quickly –> osmotic demyelination syndrome (Central pontine myelinolysis)
SIADH causes
Ectopic ADH (small cell lung cancer), CNS disorders/headtrauma, pulmonary disease, drugs (e.g. cyclophosphamidee)
Tx of SIDADH
Fluid restriction, salt tablets, IV hypertonic saline, diuretics, conivaptan, tolvaptain, demeclocycline
MOA of vaptans
Vasopressin receptor antagonists
Ddx between SIADH and psychogenic polydipsia
Increased urine osmo in water deprivation test –> psychogenic polydisia
Causes of hypopituitarism
Nonsecreting pituitary adenoma, craniopharyngioma, sheean syndrome, empty sella syndrome, pituitary apoplexy, brain injury, radiation
Tx of hypopituitaryism
HRT
Sheehan syndrome
Ischemic infarct of pituitary after postpartum bleeding, pregnancy induces growth of pituitary –> more susceptible to hypoperfusion; present w/ failure to lactate, absent menstruation, cold intolerance
Empty sella syndrome
Atrophy or compression of pituitary (in sella turcica), obese women, idiopathic
Pituitary apoplexy
Sudden hemmorhage of pituitary – usually in presence of existing pituitary adenoma; presents w/ sudden severe headache, visual impairment (bitemporal hemianopia, diplopia due to CN III palsy), feats of hypopituitarism
DKA in..
DM 1
Hyperosmolar coma in
DM2
Complications of diabetes
Small vessel disease (diffuse thickening of basement membrane) -> retinopathy (hemorrhage, exudates, microaneurysms, vessel proliferation), glaucoma, neuropathy, nepropathy (nodular glomerulosclerosis, aka Kimmelstiel Wilson nodules –> progressive proteinuria [initially microalbuminuria, ACE inhibitors are renoprotective] and arteriolosclerosis–>HTN; both lead to chronic renal failure)
Large vessel atherosclerosis, CAD< peripheral vascular occlusive disease, gangren –> limb loss, cerebrovascular disease. MI most common cause of death
Osmotic damage (sorbitol accumulates in organs w/ aldose reductase/absent sorbitol DH) –> nephropathy (motor, sensory [glove and stocking distribution] and autonomic degen as well as cataracts
HbA1C DM cutoff
> 6.5%
Fasting plasma glucose DM cutoff
> 126 (fasting >8hrs)
2 hour OGTT DM cutoff
> 200
Abs in type 1 DM
Glutamic acid decarboxylase abs, destroy B cells
HLA association in type 1 DM
HLA DR3/4
Histology of type 1 DM
Islet leukocytic infiltrate
Histology of type 2 DM
Islet amyloid polypeptide (IAPP) deposits
Pathophysiology of ketoacidosis
Excess fat breakdown and increased ketogenesis from increased free fatty acids made into ketone bodies
Signs/sx of DKA
Delirium/psychosis, Kussmaul respirations, Abdominal pain/nausea/vom, dehydration, fruity breath odor
Labs in DKA
Hyperglycemia, high H+, low HCO3 (anion gap met acidosis), high blood ketones, leukocytosis, hyperkalemia (but depleted intracell K due to transcellular shift from low insulin and acidosis – so total body K is actually depleted)
Complications of DKA
Life threatening mucormycosis (by Rhizopus), cerebral edema, cardiac arrhythmias, heart failure
Tx of DKA
IV fluids, IV insulin, K+ to replete IC stores, glucose to prevent hypoglycemia if necessary
Hyperosmolar hyperglycemic state
Profound hyperglycemia and dehydration –> increased serum osmo –> elderly T2D w/ limited ability to drink
Hyperglycemia -_> excesive osmotic diuresis –>dehydration –>eventually onset of HHNS
Sx of hyperosmolar hyperglycemic state
Thirst, polyuria, lethargy, focal neuro deficits (seizures), can progress to coma and death
Labs in HHGS
Hyperglycemia (like >600), high serum osmo (>320), no acidosis
Tx of HHGS
Aggressive IV fluids, insulin
Glucagonoma
Tumor of pancreatic alpha cells –>make glucagon –> dermatitis (necrolytic migratory erythema), diabetes (hyperglycemia), DVT, declining weight, depression
Tx of glucagonoma
Ocretotide, surgery
Insulinoma
Tumor o B cells –> make too much insulin –> hypoglycemia
Will have low glc but high C peptide, ~10% cases assc w/ MEN 1, tx by resection
Whipple triad
Low blood glucose, symptoms of hypoglycemia (lethargy, syncope, diplopia), and resolution of symptoms after normalization of glucose lvls (in insulinoma)
Somatostatinoma
Tumor of delta cells –> too much somatostatin –> less secretion of secretin, CCK, glucagon, insulin, gastrin, GIP
Present w/ diabetes/glc intolerance, steatorrhea, gallstones, achlorhydria
Tx of somatostatinoma
Surgical resect, octreotide
Carcinoid syndrome caused by
Carcinoid tumores from neuroendocrine cells
Property of neuroendocrine tumors by histology
Rosettes
Cause a lot of carcinoid syndrome
Metastatic small bowel tumors (secrete high serotonin)
Sx of carcinoid syndrome
Recurrent diarrhea, cutaneous flushing, asthmatic wheezing, right sided valvular heart disease (tricuspid regurg, pulmonic stenosis
Labs in carcinoid syndrome
High 5HIAA in urine, niacin def
Tx of carcinoid syndrome
Surgical resection, somatostatin analog (octreotide)
Rule of 1/3s
1/3 of carcinoid tumors metastasize, 1/3 present w/ 2nd malignancy, 1/3 are multiple
Most common malignancy in SI
Carcinoid tumor
Z-E syndrome
Gastrin secreting tumor (gastrinoma) of pancreas or duodenum –> acid hyper secretion –> recurrent ulcers in duodenum and JEJUNUM
Presentation: abdominal pain (PUD, distal ulcers)< diarrhea (malabsorption)
Z-E Syndrome test
Positive secretin stim test – gastrin levels elevated after admin of secretin which normally inhibs gastrin
Z-E association
MEN1
MEN syndrome inheritance
AD
MEN 1 disease
Pituitary tumors (prolactin or GH) Pancreatic tumors (Z-E, insulinomas, VIPomas, glucagonomas) parathyroid adenomas
MEN 1 genetics
Menin mutation – tumor suppressor on chr 11
MEN 2A disease
Parathyroid hyperplasia
Medullary thyroid carcinoma (C cells – req prophylactic thyroidectomy)
Pheochromocytoma
MEN 2A genetics
RET in cells of neural crest origin
MEN 2B disease
Medullary thyroid carcinoma
Pheochromocytoma
Mucosal neuromas (oral/intestinal ganglioneuromatosis)
Marfanoid habitus
MEN 2B genetics
RET mutation