5/30 UWorld Flashcards
What is the presentation of secondary adrenal insufficiency
o Lack of cortisol due to decreased ACTH = weakness, fatigue, weight loss
o Aldosterone synthesis is preserved (controlled by RAAS) à no hypotension or hyperkalemia
o ACTH low = no hyperpigmentation
What is the most common cause of tertiary adrenal insufficiency
Usually caused by abrupt withdrawal of exogenous steroids after chronic usage
Describe steps of Gq pathway
Binding/activation of Gq = activation of phospholipase C (which stimulates hydrolysis of membrane-bound phospholipids) = PLC releases IP3 and DAG = IP3 liberates intracellular Ca2+ and DAG activates protein kinase C = ultimately leads to smooth muscle contraction
Describe steps of Gs pathway
Binding/activation of Gs = activation of adenylate cyclase = adenylate cyclase cleaves ATP to form cAMP = cAMP activates protein kinase A
What are the positive serum markers in neuroblastoma
Bombesin and NSE (+)
Differentiate Cushing disease vs. Cushing syndrome
Cushing syndrome = increased cortisol
Cushing disease = increased cortisol secondary to ACTH-secreting pituitary adenoma
What is Addison disease
Primary adrenal insufficiency due to autoimmune destruction of the adrenal gland
What is Jod-Basedow phenomenon
- Iodine-induced hyperthyroidism
- Due to a patient with iodine deficiency and partially autonomous thyroid nodule being repleted of iodine
What is Riedel thyroiditis and its presentation
- Thyroid replaced by fibrous tissue
- Fibrosis may extend to local structures, mimicking anaplastic carcinoma
- Presentation:
- Euthyroid or hypothyroid
- Fixed, hard (rock-like), painless goiter
What are the 2 main types of chronic complications in diabetes
- Nonenzymatic glycosylation (leads to leaky vessels)
- Small vessel disease
- Retinopathy
- Nephropathy
- Large vessel disease
- Atherosclerosis, CAD, MI
- Gangrene
- Small vessel disease
- Osmotic damage
- Recall:
- Glucose -> (aldose reductase) -> sorbitol -> (sorbitol dehydrogenase) -> fructose
- Sorbitol accumulation in organs with aldose reductase and decreased or absent sorbitol dehydrogenase
- Sorbitol is an osmol that increases osmotic pressure causing:
- Neuropathy (glove and stocking)
- Cataracts
- Recall:
What is the cause/presentation of pseudohypoparathyroidism?
- Due to end organ resistance to PTH due to defect in the PTH receptor
- Present with:
- Hypocalcemia
- Hyperphosphatemia
- Elevated PTH
What is Albright hereditary osteodystrophy?
- Pseudohypoparathyroidism type 1a (Albright hereditary osteodystrophy)
- Unresponsiveness of kidney to PTH à hypocalcemia despite elevated PTH
- Characterized by short stature, short metacarpal, and short metatarsals
- Autosomal dominant disorder
- Due to defective Cs protein a-subunit, causing end-organ resistance to PTH
- Defect must be inherited by mother due to imprinting
Cause and presentation of primary hyperparathyroidism
- Due to parathyroid adenoma or hyperplasia
- Presentation:
- THINK: Stones, thrones, bones, groans, psychiatric overtones
- Hypercalcemia, increased PTH
- Renal stones
- Polyuria (thrones)
- Osteitis fibrosa cystica (cystic bone spaces filled with brown fibrous tissue)
- Weakness and constipation (groans)
- Depression (psychiatric overtones)
- THINK: Stones, thrones, bones, groans, psychiatric overtones
Pathogenesis and presentation of familial hypocalciuric hypercalcemia
- Due to defective G-coupled Ca2+ sensing receptors (e.g. parathyroids, kidney)
- Higher levels of Ca2+ are needed in order to suppress PTH
- Causes excessive renal Ca2+ reuptake, leading to mild hypercalcemia and hypocalciuria with normal to increased PTH levels
What are neurophysins and what might a mutation cause?
- Neurophysin = carrier protein for oxytocin and vasopressin from hypothalamus to posterior pituitary
- Mutation in neurophysin can lead to defective transport of vasopressin = Central diabetes insipidus
What is pituitary apoplexy (cause, treatment)
- Acute hemorrhage into the pituitary gland
- Occurs most often in patients with preexisting pituitary adenoma
- Cardiac collapse caused by ACTH deficiency and subsequent adrenocortical insufficiency
- Treatment – Medical emergency
- Glucocorticoid replacement (to prevent life-threatening hypotension)
- Surgical decompression
- Treatment – Medical emergency
What is pseudopseudohypoparathyroidism?
Physical exam features of Albright hereditary osteodystrophy but without end-organ PTH resistance (PTH levels normal)
Occurs when defective Cs protein a-subunit is inherited from father
What type of collagen makes up mature scar tissue?
Type I
What type of collagen makes up granulation tissue
Type III
What is the triad of symptoms associated with cardiac tamponade
Beck triad: hypotension, increased venous pressure (JVD), distant heart sounds
What is one of the more severe consequences of homocysteinuria
Increased risk of thrombotic events
What is the mutation in Marfan syndrome
o Autosomal dominant mutation in fibrillin gene (FBN1) which codes for a protein responsible for the production and maintenance of elastin fibers
Describe the steps that occur due to carotid sinus massage
- Causes increased stretch of carotid baroreceptor in order to simulate increased BP = increased afferent firing from the carotid sinus = increased efferent parasympathetic firing = slowed conduction though the AV node = prolonged AV refractory period = slowed HR
Why does Verapamil not have any significant effect on skeletal muscle?
Unlike cardiac muscle, skeletal muscle does not rely on influx of Ca2+ to stimulate extra calcium release
