Endocrine Flashcards
Wheezing (asthma symptoms) + diarrhea + facial flushing + mass lesion in appendix area: Diagnosis? Treatment?
Carcinoid syndrome
- -> ultimate treatment = surgery
- -> symptomatic treatment = Octreotide (long-acting somatostatin analog)
Most common adrenal medulla tumor in adults? kids?
adults–> pheochromocytoma (causes HTN)
kids–> neuroblastoma (does not cause HTN)
Aldosterone is secreted from?
zona glomerulosa of adrenal cortex
- -> “salt”
- -> stimulated by Renin-angiotensin
Cortisol (and some sex hormones) secreted from?
zona fasciculata of adrenal cortex
- -> “sugar”
- -> stimulated by ACTH, hypothalamic CRH
Androgens (sex hormones) are secreted from?
zona reticularis of adrenal cortex
- -> “sex”
- -> stimulated by ACTH, hypothalamic CRH
Catecholamines are secreted from?
chromaffin cells of adrenal medulla (neural crest derivative!)
–>stimulated by preganglionic sympathetic fibers
Adrenal gland drainage: Left adrenal? Right adrenal?
Left adrenal –> L adrenal vein –> L renal vein –> IVC
Right adrenal –> R adrenal vein –> IVC
(same as left and right gonadal veins!)
neurohypophysis (post pit) is derived from? adenohypophysis (ant pit)?
- neurohypophysis = neuroectoderm derivative
- adenohypophysis = surface ectoderm derivative (from Rathke’s pouch)!
Rathke’s pouch gives rise to?
Adenohypophysis (ant pit)!
–> Rathke’s pouch = oral ectoderm
hormones secreted from posterior pituitary?
- ADH
- Oxytocin
*made in hypothalamus, then shipped to post pituitary
hormones from anterior pituitary?
- which are acidophils?
- basophils?
“FLAT PiG”
- FSH
- LH
- ACTH
- TSH
- Prolactin
- GH
- Acidophils: GH, Prolactin
- Basophils = “B-FLAT” = FSH, LH, ACTH, TSH
alpha- vs beta-subunit of pituitary hormones:
- alpha = common to TSH, LH, FSH, hCG
- beta = determines hormone specificity; different in all of them!
Hormones produced by alpha, beta, and delta cells of Islets of Langerhans in pancreas?
alpha cells –> glucagon (peripheral)
beta cells –> insulin (central)
delta cells –> somatostatin (interspersed)
- note: somatostatin is also produced by delta cells in gastric mucosa and throughout gut
- insulin inhibits glucagon release by alpha cells!
Does insulin cross the placenta?
nope!
Effects on insulin release of:
- GH
- somatostatin
- Beta-agonists
- alpha-agonists
GH–>increase insulin
Somatostatin–>decreases insulin
Beta-agonists–>stimulate insulin
Alpha-agonists–>inhibit insulin
Cell types that don’t need insulin for glucose uptake?
“BRICK L”
- Brain
- RBCs
- Intestine
- Cornea
- Kidney
- Liver
GLUT-1
- RBCs
- Brain
*tissues with GLUT-1 receptors take up glucose regardless of insulin levels
GLUT-2
- beta islet cells
- liver
- kidney
- small intestine
GLUT-4
- Requires insulin to be activated!
- Adipose tissue
- Skeletal muscle
Anabolic effects of insulin (X6)
1) increases glucose transport into adipose and skeletal muscle
2) increases glycogen synthesis and storage
3) increases TG synthesis and storage
4) increases Na retention in kidneys
5) increases protein synthesis in muscles
6) increases cellular uptake of K and AAs
Glucagon:
- secreted by?
- secreted in response to?
- inhibited by?
- effects?
- secreted by alpha cells of islets of pancreas
- secreted in response to hypoglycemia
- inhibited by: insulin, hyperglycemia, somatostatin
- effects:
- ->glycogenolysis, gluconeogenesis
- ->lipolysis and ketone production
- ->increases glucose production/release so in effect also increases insulin release
Bromocriptin
dopamine agonist
–>inhibits prolactin secretion; so, can be used to treat prolactinomas
Drug types that stimulate prolactin secretion?
- Dopamine antagonists (most antipsychotics)
- Estrogens (OCPs, Pregnancy)
Why is a side effect of anti-psychotic drugs galactorrhea?
- anti-psychotics are dopamine antagonists
- dopamine inhibits prolactin; if decrease dopamine, then increase prolactin
- prolactin stimulate milk production!
Prolactin functions:
- stimulates milk production in breast
- inhibits GnRH –> so decreases LH and FSH –> so inhibits ovulation in females, spermatogenesis in males
Somatotropin = Growth Hormone:
- stimulated by?
- inhibited by?
- when is their increased secretion?
- released in pulses in response to GHRH from hypothalamus
- increased secretion during exercise and sleep
- secretion inhibited by glucose and somatostatin
17-alpha-hydroxylase deficiency:
- what’s increased/decreased?
- symptoms
- increased MCs (aldosterone)
- decreased GCs (cortisol) and androgens
- symptoms:
- ->Hypertension
- ->Hypokalemia
- –>XY: decreased DHT –> pseudohermaphroditism (looks female, but no internal reproductive structures b/c of mullerian inhibiting factor)
- ->XX: looks female, has normal internal sex organs, but lacks secondary sex characteristics)
phenotypic female who lacks internal reproductive structures; has HTN and hypokalemia
17-alpha-hydroxylase deficiency
–>XY pseudohermaphrodite, but decreased DHT; no internal organs b/c of MIF
phenotypic female with normal internal sex organs, but lacks secondary sex characteristics; has HTN and hypokalemia
-XX with 17-alpha-hydroxylase deficiency
21-hydroxylase deficiency:
- what’s increased/decreased?
- symptoms?
- increased androgens
- decreased MCs (aldosterone) and GCs (cortisol)
- symptoms:
- ->masculinization (female pseudohermaphrodite)
- ->hypOtension
- ->hyperkalemia
- ->increased renin activity
***this is the most common form of congenital adrenal hyperplasia
11-beta-hydroxylase deficiency:
- what’s increased/decreased?
- symptoms?
- increased: Androgens and 11-Deoxycorticosterone (not aldosterone though)
- decreased: GCs (cortisol) and Aldosterone
- symptoms:
- ->Hypertension (d/t 11-deoxycorticosterone)
- ->Masculinization
Finasteride
- inhibits 5-alpha-reductase
- ->so: decreased DHT
- ->used to treat male baldness! and BPH
Functions of Cortisol (X5):
“BBIIG”
1) Blood pressure maintenance (stimulates alpha-1 receptors on arterioles)
2) decreased Bone formation (side effect = osteoporosis)
3) anti-Inflammatory/Immunosuppressive
4) increases Insulin resistance (diabetogenic)
5) increases Gluconeogenesis, lipolysis, proteolysis
source of PTH?
-chief cells of parathyroid
PTH functions/effects (X4):
1) increases bone resorption–>increases Ca and P
2) increases kidney reabsorption of Ca (in distal convoluted tubule)
3) decreases kidney reabsorption of phosphate
4) increases vitamin D (calcitriol) production by stimulating kidney 1-alpha-hydroxylase
- **stimulates osteoclasts (and thus bone resorption) by increasing production of M-CSF and RANK-L in osteoblasts, which stimulates osteoclasts
- **low serum Phosphorous stimulates vitamin D conversion to active form –> vitamin D stimulates phosphate release from bone and increases phosphate reabsorption (though PTH causes decreased phosphate reabsorption)
what stimulates PTH secretion?
- decreased serum Ca
- decreased serum Mg
vitamin D3 vs D2?
D3–> from sun
D2–> from plants
*both are converted to 25-OH vitamin D in liver and to 1,25-(OH)2 vitamin D (active form) in kidney
Conversion of vitamin D to active form:
- enzyme?
- what stimulates enzyme?
- where does it happen?
1-alpha-hydroxylase
- PTH stimulates enzyme
- in kidney
functions of vitamin D (X2):
- increase dietary Ca and P absorption
- increase bone resorption of calcium and phosphate (increases osteoclasts)
why is their increases vitamin D and hypercalcemia in sarcoidosis?
-b/c granulomas –> macrophages generate vitamin D (active form)
Source of Calcitonin?
Parafollicular (C) cells of thyroid (neural crest derivative!)
Medullary thyroid carcinoma:
abnormal growth of C-cells (doesn’t really affect Calcium metabolism though; despite that Calcitonin is released from C cells)
hormones that use cAMP signaling pathways:
“FLAT CHAMP + GCG” (all the ant pit hormones, except prolactin and GH)
- FSH
- LH
- ACTH
- TSH
- CRH
- hCG
- ADH (V2 receptor)
- MSH (melanocyte stimulating hormone)
- PTH
- GHRH
- Calcitonin
- Glucagon
hormones that use cGMP signaling pathway:
- Vasodilators:
- ANP
- NO
hormones that use IP3 signaling pathway:
“GOAT + HAG” (post pit hormones!)
- GnRH
- Oxytocin
- ADH (V1 receptor)
- TRH
- Histamine (H1)
- Angiotensin II
- Gastrin
hormones that use cytosolic steroid receptors:
“VET CAP” (adrenal hormones + vitamin D!)
- Vitamin D
- Estrogen
- Testosterone
- Cortisol
- Aldosterone
- Progesterone
hormones that use nuclear steroid receptors:
-Thyroid hormones –> T3, T4
hormones that use intrinsic tyrosine kinase (MAP kinase pathway) signaling pathway:
- growth factors:
- insulin
- IGF-1
- FGF (fibroblast growth factor)
- PDGF (platelet-derived growth factor)
hormones that use receptor-associated tyrosine kinase (JAK/STAT pathway) signaling pathway:
- Prolactin
- GH
- cytokines (IL-2, IL-6, IL-8…)
Which is the active form of hormones: bound or unbound?
-unbound –> free hormone = active hormone
SHBG (sex hormone-binding globulin):
- what happens if increased in men?
- if decreased in women?
- during pregnancy?
- if increased in men–> decreased free testosterone –> gynecomastia
- if decreased in women–> increased free testosterone–> hirsutism
*have increased SHBG levels during pregnancy
Source of T3 vs T4?
T4 is from follicles of thyroid
T3 is formed from T4 conversion in blood
4 main functions of T3:
- 4 B’s:
1) Brain maturation (CNS maturation)
2) Bone growth (synergistic with GH)
3) Beta-adrenergic effects (Beta-1 receptors in heart–> increased CO, HR, SV, contractility)
4) increased BMR (via Na/K-ATPase activity –> so increased O2 consumption, RR, body temp)
*Also: increased glycogenolysis, gluconeogenesis, lipolysis
TBG:
- what is it?
- how is it affected in hepatic failure? pregnancy? OCP use?
thyroxine-binding globulin –> binds most T3/T4 in blood
- ->only free hormone is active
- reduced in hepatic failure
- increased in pregnancy and OCP use (increased estrogen–>increased TBG)
TSI
thyroid-stimulating-immunoglobulin
–>acts like TSH to stimulate follicular cells in Grave’s disease
anti-thyroid peroxidase antibodies
Hashimoto’s
Wolff-Chaikoff effect:
transient decrease in T3/T4 due to ingestion of iodide, which inhibits thyroid peroxidase, and therefore organification
–> hypothyroidism symptoms
Cushing’s syndrome
increased cortisol; causes vary
1 cause of Cushing’s syndrome?
Exogenous/Iatrogenic steroids–> increased cortisol–> decreased ACTH and decreased CRH
Endogenous causes of Cushing’s syndrome: (and ACTH levels)
1) Cushing’s disease –> pituitary adenoma –> increased ACTH secretion
2) Ectopic ACTH: nonpituitary tissue making ACTH (have very high ACTH; ie from Small cell lung cancer, bronchial carcinoids)
3) Adrenal: adenoma, carcinoma, nodular adrenal hyperplasia –> decreased ACTH (very low/undetectable)
Dexamethasone test
test to determine cause of Cushing’s syndrome
Which cause of Cushing’s syndrome is affected by Dexamethasone?
ACTH-Pituitary tumor –> get decreased cortisol levels when give a high dose of dexamethasone
Causes of primary hyperaldosteronism?
- results?
- treatment?
Caused by adrenal hyperplasia or aldosterone-secreting adrenal adenoma (Conn’s syndrome)
- Effects:
- hypertension
- hypokalemia
- LOW plasma renin
- metabolic alkalosis
- Trtmnt:
- surgery to remove tumor
- K-sparing diuretic –> aldosterone antagonist