Endocrine random facts Flashcards
What can you use to treat HIV associated lipodystrophy?
Tesamorelin (a GHRH analog)
What are epinephrine’s effects on the pancreas?
Stimulates both beta-2 and alpha-2, but alpha-2 inhibitory effect predominates so overall inhibitory effect. Pretreatment with an alpha-2 blocker would cause epinephrine’s effect on beta-2 to be predominant and increase insulin secretion
How are prolactin and the thyroid hormones related?
TRH increases prolactin secretion (eg. in primary or secondary hypothyroidism)
What is the other name for IGF-1?
Somatomedin C
What is the effect of growth hormone on blood sugar?
GH increases insulin resistance (diabetogenic)
What do ghrelin and leptin do?
Ghrelin stimulates hunger and GH release and is produced by the stomach. Leptin is the satiety hormone produced by adipose tissue. Sleep deprivation leads to decreased leptin production
What regulates ADH?
Osmoreceptors in hypothalamus (primary), hypovolemia (secondary)
How does cortisol increase blood pressure?
- Upregulates alpha-1 receptors on arterioles leading to increased sensitivity to norepinephrine and epinephrine, 2. At high concentrations, can bind to mineralocorticoid receptors
Why does excess cortisol give you striae?
Decreases fibroblast activity
Relationship between pH and calcium homeostasis
Increase in pH causes an increased affinity of albumin to bind to calcium which causes hypocalcemia (cramps, pain, paresthesias, carpopedal spasm)
What type of cells secrete PTH?
Chief cells of the parathyroid
Where in the kidney does PTH cause the excretion of Ca and PO4?
Ca in the DCT, PO4 in the PCT
Where is calcitonin from?
Parafollicular cells of the thyroid
Which hormones act through cAMP?
FSH, LH, ACTH, TSH, CRH, hCG, ADH (V2 receptor), MSH, PTH, calcitonin, GHRH, glucagon
FLAT ChAMP (plus a few more)
Which hormones act through cGMP?
ANP, BNP, NO (EDRF)
Think vasodilators
Which hormones act through IP3?
GnRH, Oxytocin, ADH (V1 receptor), TRH, Histamine (H1 receptor), Angiotenin II, Gastrin
GOAT HAG
Which hormones act through an intracellular receptor?
Vitamin D, Estrogen, Testosterone, T3/T4, Cortisol, Aldosterone, Progesterone
VETTT CAP
Which hormones act through an intrinsic tyrosine kinase?
Insulin, IGF-1, FGF, PDGF, EF
MAP kinase pathway
Which hormones act through a receptor-associated tyrosine kinase?
Prolactin, Immunomodulators (eg, cytokines IL-2, IL-6, IFN), GH, G-CSF, Erythropoietin, Thrombopoietin,
JAK/STAT pathway
What converts T4 to T3
5’-deiodinase
What is the enzyme responsible for oxidation and organification of iodide as well as coupling of monoiodotyrosine (MIT) and di-iodotyrosine (DIT)?
Peroxidase (propylthiouracil inhibits both peroxidase and 5’deiodinase. Methiazole inhibits peroxidase only)
What is the Wolff-Chiakoff effect?
Excess iodine temporarily inhibits thyroid peroxidase leading to decreased iodine organification and decreased T3/T4 production
What should you think of if you see Homer-Wright pseudo rosettes?
Neuroblastoma
Presentation of neuroblastoma?
Irregular mass crossing the midline OR opsoclonus-myoclonus syndrome (“dancing eyes-dancing feet”). HVA and VMA increased in the urine. Bombazine and neuron-specific annuals positive
What mutation is neuroblastoma associated with?
Overexpression of N-myc oncogene
Treatment for pheo?
Alpha blockers THEN beta blockers THEN surgical resection
Histologic findings in Hashimoto’s
Hurthle cells, lymphoid aggregate with germinal centers
Empty-appearing nuclei with central clearing, nuclear grooves
Papillary thyroid carcinoma, increased risk with RET and BRAF mutations, childhood irradiation, excellent prognosis
Cancer invading the thyroid capsule
Follicular carcinoma, good prognosis
Sheets of cells in an amyloid stroma
Medullary carcinoma, associated with MEN 2A and 2B (RET mutations)
Hypocalcemia, shortened 4th/5th digits, short stature
Pseudohypoparathyroidism (Albright hereditary osteodystrophy)- unresponsiveness of kidney to PTH. Autosomal dominant
Familial hypocalciuric hypercalcemia
An AD dx caused by defective Ca sensing receptor on parathyroid cells. PTH cannot be suppressed by an increase in Ca level
What type of receptor are Calcium sensing receptors?
Transmembrane G-protein coupled receptors
What can primary hyperparathyroidism cause?
Stoans, bones, groans, and psychiatric overtones. Also osteitis fibrous cystica
Cystic bone spaces filled with brown fibrous tissue
Osteitis fibrosa cystica (Brown tumor consisting of deposited hemosiderin from hemorrhages, causes bone pain)
What is the most common cause of death in kids with gigantism?
Heart failure
What does acromegaly predispose you to?
Increased risk of colorectal polyps and cancer
Treatment for nephrogenic DI?
HCTZ, indomethacin, amiloride, and hydration
What can you use to treat SIADH?
Fluid restriction, IV hypertonic saline, conivaptan, tolvaptan, demeclocycline
Deficiency of what enzyme in certain organs leads to osmotic damage in diabetes?
Sorbitol dehydrogenase (causes cataracts)
Most common initial sensory impairment in pts with diabetes
A loss of vibrational sense because it affects the Pacinian corpuscles
Histology of type 1 and type 2 diabetes
Type 1- islet leukocytic infiltrate, Type 2- islet amyloid polypeptide (IAPP) deposits
Presentation of glucagonoma
Dermatisis (necrolysic migratory erythema), diabetes, DVT, and depression
Presentation of carcinoid syndrome
Recurrent diarrhea, cutaneous flushing, asthmatic wheezing, right-sided valvular disease
Tx for carcinoid syndrome
Surgical resection, somatostatin analog (octreotide)
How do you test for Z-E syndrome?
Secretin stimulation test: positive (in Z-E) if gastrin levels remain elevated after administration of secretin, which normally inhibits gastrin release
MOA of biguanides
(Metformin) Decreases gluconeogenesis, increases glycolysis, increases peripheral glucose uptake
SE of metformin
GI upset, lactic acidosis (thus contraindicated in renal insufficiency- check Creatinine!)
MOA of sulfonylureas
Close K+ channel in beta-cell membrane
What are the sulfonylureas?
First gen: chlorpropamide, tolbutamide; second gen: glimepiride, glipizide, glyburide
SE of thiazolidinediones
Weight gain, edema, hepatotoxicity, HF, increased risk of fractures
What are the GLP-1 analogs?
Exenatide, liraglutide
What are the DPP-4 inhibitors?
Linapgliptin, saxagliptin, sitagliptin
What is pramlintide
An amylin analog, decreases gastric emptying, decreases glucagon
What is canagliflozin?
An SLGT-2 inhibitor. Blocks reabsorption of glucose in the PCT. DE: glucosuria, UTIs, vaginal yeast infections. Monitor BUN/Cr
What is are the alpha-glucosidase inhibitors and how do they work?
Acarbose, miglitol. Inhibit intestinal brush-border alpha-glucosidases.
What hyperthyroid med do you use in pregnancy?
PTU
What is cinacalcet?
It sensitizes Ca-sensing receptor in parathyroid gland to circulating Ca causing decreased PTH. Used for hypercalcemia due to primary or secondary hyperparathyroidism.
