Endocrine Flashcards
Which organs are involved in MEN 1?
Pituitary, Parathyroid, Pancreas (Rhombus with all Ps)
Which organs are involved in MEN 2A?
Thyroid, Parathyroid and Pheochromocytoma (From rhombus to house, abre abajo)
Which organs are involved in MEN 2B?
Thyroid, Pheochromocytoma and Marfanoid habitus.
What is the presentation of 21-hydroxylase deficiency?
Hypotention, Hyperkalemia (low aldo), Virilization (high T)
What is the presentation of 17alpha-hydroxylase deficiency?
Can only produce mineralocorticoids. Hypertension, Hypokalemia. Lack of sexual development and pseudohermaphroditism in males.
What is the presentation of 11beta-hydroxylase deficiency?
Hypertension (Excess of 11-deoxycorticosterone which is ~ aldo), Virilization
Which glucocorticoid is preferred during childhood?
Hydrocortisone
Which glucocorticoid has mineralocorticoid activity?
Fludrocortisone
What is the thyroglossal duct?
The thyroid migrates down from the foramen cecum to it’s position. The duct is a remnant of this migration. Persistant duct is palpable. The most common location for an ectopic thyroid is sublingual.
How do you distinguish between Cushing disease and ectopic ACTH production?
High dose dexamethasone will suppress ACTH production in Cushing disease but in ectopic production (ie. small cell lung cancer) ACTH stays elevated even at high doses.
What is the effect of glucocorticoids on the liver?
They are potent activators of gluconeogenesis. (ie. hyperglycemia in Cushing syndrome)
What are the mechanism of action and side effects of Colchicine?
Colchicine affects tubulin polymerization. Nausea, abdominal pain and diarrhea.
What does Ras need to bind in order to activate?
GTP
What are neurophysins?
Carriers of Oxitocin and ADH from the thalamus to the posterior pituitary where they are secreted. Lack of neurophysins would lead to DI.
What is the relation between ADH and pro-opiomelanocortin (POMC)?
They are made from the same precursor polypeptide just cleaved in different ways. Both are made in the anterior pituitary.
Rank the different types of Insulin from the quickest to the slowest action. [The numbers represent the peak.]
Aspart, Lispro, Glulisine (1 hour) Regular (2.5 hours) NPH (Neutral Protamine Hagedorn) (7 hours) Detenir (8 hours) Glardine (24 hours with no peak)
What is the neurological sign of hypocalcemia?
Chvostek’s Sign = Facial Nerve Hyperexcitability. Elicited by tapping on the jaw or on the Facial nerve just anterior to the ear.
What are the lab findings in mineralocorticoid excess?
hypertension, hypoK, low renin, and non-supressable aldosterone. Na is generally normal and edema is not generally seen.
Which glucose transporter is responsive to insulin and where is it located?
GLUT-4 on muscle cells and adipocytes
Where in the cell is the T3 receptor?
In the nucleus
How does TNF-alpha cause insulin resistance?
Activates Serine Kinases which phosphorylate IRS-1 which inhibits the Tyrosine Kinase phosphorylation of IRS-1 by the Insulin Receptor.
What is the only pituitary hormone that is inhibited by the hypothalamus? All the other ones are activated.
Prolactin
What does growth hormone excess do?
It causes IGF-1 secretion by the liver. If it happens before close of the growth plates it causes gigantism. If it happens in adulthood it causes acromegaly.
What are the two types of symptoms of hypoglycemia?
Adrenergic (sweating, tremor, palpitations, hunger) & CNS (behavioral, confusion, vision, seizures)
Compare and contrast PTH and Calcitriol. What about calcitonin.
Both increase serum Ca++. Calcitriol increases GI bone absorption and decreases PTH. PTH stimulates osteoclasts, increases Calcitriol and decreases phosphorus reabsorption from the kidneys. Calcitonin directly oposes PTH.
What is the mechanism of action of propylthiouracil?
1) Blocks thyroid peroxidase and 2) prevents the T4 to T3 conversion by blcoking 5’-deiodinase.
What is the mechanism of action of methymazole?
It blocks thyroid peroxidase.
What ligands use the JAK/STAT pathway?
Cytokines, Prolactin, Growth hormone and IL-2. These are tyrosine kinase associated receptors. (Not tyrosine kinase receptors themselves.)
What are glitazones/thiozolidinediones used for and what is their main toxicity?
Used for type 2 DM and can cause hepatotoxicity. They increase insulin sensitivity by binding the PPAR-gamma transcription regulator.
How does cortisol control catecholamine synthesis?
It promotes Phenylethanolamine-N-methyltransferase (PNMT) in the adrenal medulla. This protein converts NE to Epi.
Describe the histology seen in Hashimoto’s Thyroiditis?
Mononuclear, parenchymal infiltration with well defined germinal centers.
Why can patients with GU tumors have an increase in thyroid hormones?
Some GU tumors produce hCG, especially teratomas or other non-seminomatous germ cell tumors. hCG has slight affinity for the TSH receptor.
What are the 6 Ps of congenital hypothyroidism?
Pot-bellied Pale Puffy-faced Protruding Umbilicus Protuberant Tongue Poor brain development
Hypertension, opsoclonus-myoclonus and a retroperitoneal mass are suggestive of…
Neuroblastoma. Adrenal medulla tumor in children. Associated with N-myc mutations.
What are the lab findings in primary adrenal insufficiency? What is a risk factor for it? (Addison’s Disease)
Hyperkalemia, hyponatremia, hypochloremia and metabolic acidosis. Patients with type I diabetes can get it.
Describe the signaling pathway of the insulin receptor?
Tyrosine Kinase -(+)-> Protein Phosphatase 1 -(-)-> Glycogen Phosphorylase
Also…
Protein Phosphatase 1 -(-)-> fructose-1,6-bisphophatase -(+)-> Gluconeogenesis
Also…
Tyrosine Kinase -(+)-> Glycogen Synthase
Which drugs should not be given while on radioactive iodine treatment?
Potassium Perchlorate and Potassium Pertechnetate because they are competitive inhibitors of the Sodium Iodine Symporter (NIS). Thionamides inhibit peroxidase.
Describe the clinical presentation of a Medullary Carcinoma of the Thyroid?
Solid lump on the thyroid and increased serum calcitonin. You MUST check for Pheochromocytoma as most of these tumors are associated with MEN 2A or MEN2B.
What is the mechanism of action of propylthiouracyl and methimazole?
Inhibit organification and coupling of iodotyrosines. Propylthiouracyl also prevent peripheral T4->T3 conversion.
What is Eplerenone?
Aldosterone Receptor blocker. Just like Spironolactone but with fewer side effects.
What are the Sulfonylurea drugs and what is their mechanism of action?
1st G: Tolbutamide, Chlorpropamide
2nd G: Glyburide, Glimepiride, Glipizide.
They work by closing K channels and thus inducing Insulin release.
What is the typical picture of Glucagonoma?
DM (hyperglycemia), anemia and necrolytic erythema.
What is the treatment for adrenal crisis?
High dose corticosteroids.
Which hormone is involved in the pathogenesis of gestational diabetes?
Human Placental Lactogen causes insulin resistance and simultaneously increases insulin secretion.
Which lipids are believed to increase insulin resistance?
Free Fatty Acids and Triglycerides.
