UWorld-Endocrinology
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53 terms
Terms | Definitions |
|---|---|
 hirsutism | male-like pattern terminal hair (coarse, curly, and pigmented) growth in females idiopathic: increased conversion of testosterone into DHT by 5-alpha-reducatase or due to higher sensitivity of hair follicles to DHT *occurs due to increased testosterone secretion or increased conversion of testosterone to DHT causes: idiopathic (most likely cause if reg menses and no Sx of virulization), PCOS, Cushing syndrome, ovarian and adrenal tumors Tx: spironolactone (blocks androgen receptors), flutamide (testosterone receptor antagonist), finasteride (5-alpha-reductase inhibitor) *should be distinguished from virilization |
| virilization | hirsutism clitoromegaly increased muscle mass acne increased libido voice deepening |
| clomiphene | antiestrogen=>interferes with neg feedback of estrogens on hypothalamus and pituitary increases synthesis of GnRH=>increases gonadotropins used to Tx infertility esp when assoc with anovulation |
| mitotane | andrenocorticolytic drug clinical use: adrenocortical carcinoma |
| medroxyprogesterone (Depo Provera) | progesterone-only OC administered as intramuscular injection once every 12wks |
| mifepristone (RU-486) | synthetic steroid with anti-progestin and anti-glucocorticoid effects used primary as abortifacient |
| danazol | synthetic androgen clinical use: endometriosis, hereditary angioedema side effects: hirsutism, masculinization, fluid retention, and weight gain |
| spironolactone | K+-sparing diuretic anti-andronergic properties: blocks androgen receptors at hair follicles, decreases testosterone prod side effects: gynecomastia and testicular atrophy in men |
| Klinefelter syndrome | typical genotype: 47 XXY; most clinical manifestations result of extra X c'some; can occur whe there is "non-disjunction" of sex c'somes during meiotic division in either parent presentation: hypogonadism, small firm testes, elongated limbs, gynecomastia seminiferous tubules progressively destroyed and hyalinized=>testes small and firm; serum inhibin decreased, decreased Leydig cells=>low testosterone, ED, increased LH and FSH *hypogonadism causes delayed epiphyseal fusion=>elongated limbs **most are infertile |
| Kallman's syndrome | congenital absence of GnRH-secreting neurons |
| cryptorchidism | seminiferous tubules are damaged interstitial Leydig cells are preserved |
| insulin | acts via tyrosine kinase that also has cytosolic tyrosine kinase activity=>*activates protein phosphatase=>dephosphorylates (activates) glycogen synthase=>glycogen synthesis *protein phosphatase dephosphorylates and inactivates F16BP=>inhibits gluconeogenesis anabolic hormone that promotes synthesis of glycogen (in liver and skeletal m.), TG, nucleic acids, and proteins inhibits glycogenolysis and gluconeogenesis |
| protein kinase A | primary intracellular affector enzyme in G-protein/adenylate cyclase 2nd messenger system increased levels of cAMP stim PKA |
| phospholipase C | active in G-protein/IP3/Ca2+ 2nd messenger system hormone binds receptor and activates G-protein=>activates PLC=>degrade phospholipids to IP3 and DAG *both DAG and increased intracellular Ca2+ caused by IP3 will activate PKC |
| janus protein kinase (JAK) | 2nd messenger system for peptide hormones in JAK-STAT pathway *signal transducers and activators of transxn JAK has tyrosine kinase activity |
| lipoxygenase | enzyme involved in arachidonic acid metabolism responsible for pathway that synthesizes leukotrienes |
| congenital adrenal hyperplasia | encompasses a group of disorders that stem from various defects in enzymes involved in cortisol biosynthesis=>increased cortisol precursors proximal to enzyme deficiency 21-hydroxylase deficiency the most common cause=>90%; converts 17-hydroxyprogesterone to 11-deoxycortisol in zone fasciculata; converts progesterone to deoxycorticosterone in zona glomerulosa *accum cortisol precursors diverted towards adrenal androgen biosynthetic pathway=>increased adrenal androgens **low cortisol levels stim ACTH prod=>further increases adrenal androgens production ***female infants get masculinized and males look normal |
| metabolic syndrome | group of risk factors: HTN abdominal obesity atherogenic dyslipidemia insulin resistance |
| high waist to hip ratio associations | insulin resistance metabolic syndrome DM II *meas visceral obesity |
| amino acids with three titratable protons | histidine arginine lysine aspartic acid glutamic acid cysteine tyrosine |
| histidinemia | rare autosomal disorder that causes increased histidinemia=>pts deficient in histidase=>required for catabolism of histidine clinical manifest: speech defects, pschomotor and gen retardation, emotional disturbance *most frequent inborn metabolic disorder in Japan |
| prolactin inhibition | inhibited by dopamine=>acts on D2 dopamine receptor of lactotrophs *dopamine secreted by hypothalamus |
| Conn's syndrome | increased aldosterone secretion=>hypertrophy of glomerular layer of adrenal cortex |
| Addison's disease | autoimmune condition=>adrenal glands bc markedly atrophic *assoc with diffuse atrophy of adrenal cortex |
| Cushing's sydrome | XS cortisol production |
| essential fructosuria | in pts with essential fructosuria=>metabolism of fructose by hexokinase to fructose-6-phosphate is 1° method of metabolizing dietary fructose *this pathway not sig in normal indiv |
| glucose-6-phosphate metabolism | can be metabolized 3 ways: 1) conversion to G1P by phosphoglucomutase=>used for glycogen synthesis 2) conversion to glucose by glucose-6-phosphatase *this enzyme absent in muscle 3) conversion to 6-phosphogluconolactone by glucose-6-phosphate dehydrogenase in first step of PPP |
| aldose reductase | enzyme that concerts glucose to sorbitol plays role in development of chronic complications of diabetes has low affinity for glucose; *in normal indiv very little glucose metabolized by this enzyme but in diabetics glucose metabolism by this enzyme is high due to chronically high blood glucose concentrations |
| glucose-6-phosphatase | converts glucose-6-phosphate to glucose *only found in liver |
| McArdle's disease | type 5 glycogen storage disease=>myophosphorylase deficiency=>failure of glycogenolysis *glycogenolysis provides immed NRG for strenuous muscle contraction clinical manifest: decreased exercise tolerance, myoglobinuria, muscle pain with physical activity |
| insulin vs. glucagon | insulin opposes glucagon action glucagon stim insulin secretion from pancreas, glycogenolysis, gluconeogenesis, lipolysis, and ketone body prod insulin increases glucose, AA and K+ uptake by cells, inhibits ketoacid formation and inhibits lipolysis |
| hypoglycemia | initially manifests with pallor and sweaty skin=>worsens with bizarre behavior, convulsions, and unconsciousness can develop caught early can be self-Tx with consumption of 15-30 g of fast-acting carbs (e.g., glucose tablets, sweetened fruit juices, milk, soft drinks, or hard candy) when severe enough to induce unconsciousness parenteral Tx is required=>intramuscular glucagon injection in non-medical setting =>correct hypoglycemia by increasing hepatic glycogenolysis and gluconeogenesis=>return to consciousness within 10-15min *in medical-setting Tx with IV dextrose |
| indications for Tx with subcutaneous epinephrine | indicated primarily for Tx of anaphylaxis |
| indications for Tx with cortisol | used as immunosuppressive drug in Tx of allergic rxns can be injected or applied topically |
| indications for Tx with desmopression | used to Tx central diabetes insipidus and nocturnal enuresis also increases circulating levels of von Willebrand factor (factor VIII:R) and promotes coagulant activity of factor VIII:C |
| epinephrine and glucose metabolism | increases glucose by multiple mech: 1. liver-increased glycogenolysis and gluconeogenesis 2. skeletal muscle-decreases glucose uptake; increases alanine released from skeletal m.=>serves as source of gluconeogenesis in liver 3. adipose tissue-increases breakdown of TG=>increasing FA and glycerol in circulation=>utilized as gluconeogenetic substrates *glucagon has insig effect on adipose tissue and skeletal m. |
| 1° hypothyroidism | feat: fatigue, weight gain, constipation, slow relaxation of DTR, and dry, coarse skin TSH rise occurs well before low thyroid hormone level seen=>best marker for Dx *exception in cases of central hypothyroidism (deficiency in TSH) but cases are rare |
| 24hr urinary cortisol and dexmethasone suppression test screening | tests for Cushing syndrome feats: central obesity, skin striae, rounded facies, deposition of supraclavicular fat, and proximal weakness |
| aromatase inhibitors | anastrazole, letrozole, exemestane aromatase inhibitors that inhibit synthesis of estrogen from its androgenic substrate=>suppressing estrogen to postmenopausal levels *in Tx of metastatic cancer aromatase inhibitors are equivalent or superior to tamoxifen **3rd generation are highly selective and potent |
| aromatase | expressed in ovarian tissue and present in subcutaneous fat, normal breast tissue, and cancerous breast tissue *in postmenopausal state, extraovarian aromatase maintains a low level of estrogen in peripheral circulation |
| tamoxifen | acts as antagonist or partial agonist of estrogen receptor=>depending on tissue type breast tissue: antagonizes estrogen receptor=>used as adjuvant therapy for estrogen receptor+ breast cancer bone: partial agonist endometrium: partial agonist CV tissue: partial agonist *assoc with side effects such as DVT, thromboembolism, and endometrial cancer |
| ketoconazole and estrogen production | antifungal agent that decreases androgen synthesis by inhibiting multiple enzyme pathways involved in synthesis of androgens |
| HER2/neu | many pts with breast cancer overexpress this protein involved in cell prolif=>assoc with worse prognosis inhibition of epidermal growth factor and HER2/neu pathways can lead to apoptosis of breast cancer cells *monoclonal Ab against HER2/neu receptors (e.g., trastuzumab) have been successful in Tx of breast cancer |
| Sheehan syndrome | high estrogen levels of pregnancy stim growth of pituitary=>enlarge and bc more vascular *sig hypotension (most common cause is postpartum hemorrhage) while still large=>ischemic necrosis=>panhpopituitarism commonly see prolactin deficiency (unable to lactate), hypothyroidism, and hypocortisolism |
| autoimmune hypophysitis | inflammation of pituitary sometimes seen during late pregnancy or early postpartum present: acute with headaches, visual field defects, and cortisol deficiency |
| pituitary hypoplexy | hemorrhage into preexisting pituitary adenoma=>medical emergency present: acute, severe headache, ophthalmoplegia, and altered sensorium Tx: urgen neurosurgical consultation and stress doses of glucocorticoids |
| pituitary cancer | 1° cancer is extremely rare=>more prone to metastases due to rich vascular supply present: tumor mass effects *infiltrative lesions involving suprasellar space typically compress the pituitary stalk=>decreased hypothalamic dopamine and loss of inhibition of pituitary lactotrophs=>increased prolactin |
| MEN 2B | characteristics: Marfanoid habitus, mucosal neuromas, medullary thyroid carcinoma, pheochromocytoma |
| Marfanoid habitus | tall slender disproportionately long arms, legs, fingers |
| Ehler's Danlos syndrome | heritable CT disorder characterized by skin hyperextensibility, joint hypermobility, tissue fragility, poor wound healing, and easy brusing |
| neurofribromatosis type 1 | characterized by: café-au-lait spots cutaneous neurofibromas, axillary or inguinal freckling optic glioma iris hamartomas osseous lesions |
| neurofibromatosis type 2 | more "central" form characterized by: bilateral acoustic neuromas brain meningiomas shwannomas of the dorsal roots in spinal cord |
| MEN 1 | autosomal dominant condition characterized by: parathyroid gland tumors of pituitary gland tumors of pancreas |
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