Endocrine Flashcards
Normal migration of thyroid gland?
Thyroid gland is out pouching or pharyngeal epithelium that descends into the neck. Connected to tongue by thyroglossal duct. The foramen cecum is the dorsal surface of tongue and is a remnant.
Presentation of thyroglossal duct cyst?
Anterior midline neck mass that moves with swallowing o r tongue movt
Lingual thyroid
If only thyroid tissue present, removal could lead to hypothyroidism (in children lethargy, jaundice, feeding problems, constipation)
Congenital adrenal hyperplasia etios
21-hydroxylase deficiency - most common; dec. glucocorticoids and mineralocorticoids with increased adrenal androgens; 11B-hydroxylase - decreased glucocorticoids and inc. adrenal androgens; 17a-hydroxylase - nl mineralo, dec. androgens, estrogens, cortisols; 5a-reductase - defective conversion of testosterone to dihydrotestosterone (responsible for fusion); Side chain cleavage - conversion of chop to pregnenolone; impaired synthesis of all steroid hormones; Tx = low-dose corticosteriods to suppress ACTH secretion
MEN I
3 P’s - (hyper)Parathyroidism, Pancreas (gastrinoma -> peptic ulcer), Pituitary adenoma. Commonly presents with kidney stones + stomach ulcers.
Treatment for male pattern baldness?
5-alpha-reductase inhibitors (e.g. finasteride) b/c it is thought that enzyme in scalp doesn’t work that well
Salt-wasting v. non-salt-wasting 21-hydroxylase deficiency presentations
Girls - same; birth with ambiguous genitalia
Boys - Salt-wasting will present at 1-2 weeks with FTT, dehydration, hyperkalemia, and hyponatremia. Non-salt-wasting will present at 2-4 yrs with early virilization.
What enzyme converts Vitamin D into active form?
1-alpha hydroxylase. Resides in kidneys.
Adrenal gland subdivisions?
Cortex - zona glomerulosa (mineralocorticoids,aldo), zona fasciculata (glucorticoids, cortisol), zona reticularis (androgens); GFR = ACA
Medulla
Be wary of what side effects by which thyroid drugs?
Agranulocytosis by methimazole or PTU. WBC w/ diff for fever
Thyroid peroxidase?
Oxidation of iodide to iodine, iodination of thyroiglobuline tyrosine, and iodotyrosine coupling that forms T3, T4. TPO ab’s for Hashimoto’s.
Papillary carcinoma of thyroid FNA
Finely dispersed chromatic, ground-glass (Orphan Annie Eye), w/ intranuclear inclusions and grooves, and psammoma bodies.
Mech of hypoglycemia symptoms?
Inc. secretion of epinephrine and NE lead to sweating, tremor, palpitations, hunger, nervousness. CNS symptoms later b/c higher brain center activity decreases to conserve glucose -> behavior, confusion, stupor, seizures. Selective Beta-blockers preferable in diabetics b/c Beta-2 blockade leads to inhibition of gluconeogenesis, glycogenolysis, and lypolysis
Congenital Hypothyroidism
Lethargy, poor feeding, prolonged jaundice, constipation, hypotonia, hoarse cry. Pale, dry skin w/ myxedema, MACROglossia. Umbilical hernia. Higher incidence of ASD/VSD.
Neurophysin
Carrier proteins for oxytocin (paraventricular nuclei) and ADH (supraoptic nuclei) produced in hypothalamic nuclei. Help shuttle them to posterior pituitary. Mutation in neurophysin II for vasopressin thought to be cause of AD diabetes insipidus.
Path of Hashimoto’s?
Mononuclear, parenchymal infiltration w/ well-developed germinal centers
Pheochromocytoma rule of 10’s
10% occur as part of hereditary (MEN2, VHL), 10% b/l, 10% are extra-adrenal, 10% malignant. Tumor of chromatin tissue of adrenal medulla that increases production of NE and EPI.
Endogenous opioids?
Beta-endorphin is one derived from proopiomelanocortin (also precursor to ACTH). Stress axis ~ opioid.
Path findings in pancreas for DMT2?
Deposits of amylin (an amyloid) found in pancreatic islets. Theory: lead to beta cell apoptosis and defective insulin secretion
How to distinguish between where alkaline phosphatase is coming from?
Bone-specific Aphos is denatured by heat. Liver APhos does not.
Achondroplasia
AD. FGFR-3 point mutation leading to increased INHIBITION of cartilage proliferation. Normal trunk, shortened proximal extremities, enlarged head and frontal bossing.
Glucagonoma
Alpha-cells of pancreatic islets. Necrolytic migratory erythema, Hyperglycemia.
VIPoma
Intractable diarrhea, metabolic acidosis, hypokalemia
Somatostatinoma
Tumor of pancreatic delta-cells. Abdominal pain, gallbladder stones, constipation, steatorrhea. 2/2 to somatostatin’s inhibitory effects of insulin, glucagon, gastrin, cholecystokinin, and secretin secretion.
Gastrinoma
Neuroendocrine tumor. JEJUNAL ulcer.
Metyrapone test
11-Beta-hydroxylase inhibitor. Test for integrity of HPA axis. B/c 11-deoxycortisol builds up and doesn’t inhibit ACTH, ACTH will be released leading to a build-up of 17-hydroxycorticosteroids, which are detected as normal HPA axis.
Cells of the adrenal medulla?
Chromaffin cells
Adrenal vein venous drainage?
Same as gondal veins. Right adrenal vein goes straight into IVC whereas L adrenal vein goes to L renal vein then IVC.
Anterior pituitary secretes what hormones?
FSH, LH, ACTH, TSH, prolactin, GH, melanotropin
Three types of pancreatic cells and where are they located?
alpha = glucagon (peripheral). Beta = insulin (central). Delta = somatostatin (interspersed)
Structure of insulin proper?
alpha and beta chain. 2 Disulfide bridges between chains. 1 disulfide bridge within alpha chain.
High insulin but NOT high C-peptide?
Suggests EXOGENOUS insulin
Regulation of insulin release overview?
GLUT-2 transports glucose into Beta cells -> glycolysis -> Inc ATP/ADP ration -> stoppage pf ATP-sensitive K+ efflux -> depolarization -> opening of voltage gated Ca2+ influx -> exocytosis of insulin granules
GLUT-1?
Found in RBC’s, brain, and cornea. Insulin-independent
GLUT-2?
Found in Beta-cells, liver, kidney, and small intestine. Bi-directional and insulin-independent.
GLUT-4
Insulin-DEPENDENT glucose transporter in adipose tissue and skeletal muscle.
GLUT-5
Fructose transporter in spermatocytes and GI tract. NOT insulin dependent.
Insulin’s effect on kidney?
Increased Na+ retention
CRH f(x)?
Released by hypothalamus and tells anterior pituitary to secrete ACTH, MSH, beta-endorphin.
Dopamine f(x) in endocrine system?
Released by hypothalamus to tell anterior pituitary to make LESS prolactin. (Therefore, dopamine antagonists -> increased prolactin; and DA agonists can treat prolactinomas)
GnRH f(x)?
Released by hypothalamus to increase FSH and LH. Pulsatile for puberty and fertility. Continuous suppresses axis. It is INHIBITED by prolactin.
The function of hypothalamic somatostatin?
Inhibits the release of GH and TSH from the anterior pituitary.
TRH f(x)?
Increases TSH AND prolactin.
Effects of growth hormone?
Linear growth and muscle mass via IGF-somatmedin produced in the liver. Direct effects of GH include insulin resistance, increased fat utilization, and protein synthesis.
How is GH regulated to cause growth?
In response to GHRH, GH released in pulses during sleep and exercise. Inhibited by glucose and somatostatin.
What synthesizes ADH?
Supraoptic nuclei of the hypothalamus.
V1 vs V2 receptors?
V1 receptors lead to increased vascular smooth muscle contraction. V2 leads to increased water permeability and reabsorption in collecting tubules via increased aquaporn transcription in principal cells.
What enzyme does ACTH activate?
Cholesterol desmolase (cholesterol -> pregnenolone). Inhibited by ketoconazole.
Hypertension, hypokalemia, low DHT enzyme deficiency? Presentation? Other labs?
17-alpha-hydroxylase deficiency. Failure to make 17-hydroxyprog/preg -> dec. cortisol and sex hormones. In males, ambiguous genitalia. In females, lack secondary sexual development.
Hypotension, hyperkalemia enzyme deficiency? Presentation? Other labs?
21-alpha-hydroxylase deficiency. Failure to make mineralocorticoids and cortisol. Presentation is salt-wasting infant or precocious puberty in males and virilization in females. Labs include INC renin, inc 17-hydroxyprogesterone.
11-Beta-hydroxylase deficiency?
HTN 2/2 increased 11-deoxycorticosterone (even though aldo is low). Shunting to sex hormones leads to virilization in females.
How does cortisol affect the immune response?
Inhibits leukotriene and prostaglandin production. Inhibits leukocyte adhesion. Blocks histamine release from mast cells. Reduces eosinophils. Blocks IL-2.
How does cortisol affect blood pressure?
It up regulates alpha-1 receptors in arterioles -> increased sensitivity to catecholamines -> HTN
Calcitonin function and regulation?
Decreases bone resorption (decreases [Ca2+]). Increased serum Ca2+ will cause calcitonin secretion. No effect on osteoblasts.
How does PTH affect the kidneys?
Increases Ca2+ reabsorption at DCT (via upregulation of basolateral Ca/Na exchanger). Decreases reabsorption of phosphate reabsorption by inhibiting Na-P anti porter. Stimulates kidney 1-alpha-hydroxylase -> increased 1,25 D3 production.