Endocrine - to midterm

Question 0

3 questions to always ask about pituitary tumors

Answer 0

1. Functional (makes hormones)?
2. Mass effects?
   (ie: bitemporal hemianopsia or erosion into sinuses)
3. Production of other hormones affected?

Question 1

Types of Hormone Receptors

Answer 1

1. Cell Membrane Rs: amt hormone => response size

2. Cytoplasmic/Nuclear Rs: #Rs => response size

Question 2

Common causes of hyperprolactinemia

Answer 2

1. prolactinoma (in pituitary, often large)
2. pituitary stalk damage
3. chest wall trauma
4. kidney failure
5. drugs (esp. antipsychotics)
6. hypothyroidism (=> high TRH)

Question 3

Treatment for hyperprolactinemia

Answer 3

1. dopamine agonist –> decreases secretion AND shrinks prolactinomas!

2. surgery if unresponsive
   * none if mild

Question 4

metabolic consequences of GH-producing pituitary tumors

Answer 4

1. excess DNA, RNA & protein synth
2. FA mobilization
3. insulin resistance (use fat more than glucose)
   * irreversible bone changes

Question 5

Diagnosis for acromegaly

Answer 5

high IGF-1 & GH >1ug after oral glucose load,
Xrays (skull, hand, feet)
Pituitary MRI or CT

Question 6

Iodine deficiency

• where?
• why does it matter?

Answer 6

1. low iodine in soil @ places far from ocean (comes down in rain)
2. need iodine for thyroid hormone synthesis (100ug/day)
   (thyroglobulin + tyrosine + Iodine => T4 & T3)
   *TSH binding to THR increases thyroid uptake of Iodine!

Question 7

Function of T3 hormone

Answer 7

(binds to TRE –> histone acetylation –> activate transcription)

1. Metabolic:
   - increase O2 consumption, heat production
   - increase metabolic rate (ie: food, drugs, anesthesia)
   - increase protein/fat/cholest. synth & degrad.
2. increase SNS tone
3. normal brain dvpt in infants (need!)

Question 8

Congenital Hypothyroidsim

Answer 8

= Cretinism, due to failed thyroid dvpt.

Sx: lethargy, mental retardation, failure to grow/feed/gain weight

Question 9

Adult hypothyroidism

Answer 9

Thyroid hormone deficit,
Causes: autoimmune, thyroid damage (radioactive I, surg, drugs); low TSH (secondary)
Sx: fatigue, cold intolerance, low HR/contractility, HTN, infertility, slow reflex relaxation

Question 10

Thyrotoxicosis

Answer 10

too much thyroid hormone
(due to hyperthyroidism or thyroiditis)
Sx: heat intolerance, weight loss, stare & proptosis, high HR, A-fib., tremor

Question 11

Grave’s disease

Answer 11

familial, autoimmune stimulation of thyroid; 10x F>M.
* most common cause of hyperthyroidsim
Dx: high radioiodine uptake, low TSH, high T3/T4

Question 12

Treatment for hyperthyroidism

Answer 12

1. radioactive iodine
2. anti-thyroid hormone drugs (methimazole, PTU)
3. surgery (only if Large goiters, bleeding, etc.)

Question 13

Thyroiditis

Answer 13

destruction of thyroid follicle epithelial cells
=> initially thyrotoxic bc leak T3/T4, but then hypothyroid bc damaged.
Causes: viral, autoimmune, radiation, drugs (amiodarone, iodine)

Question 14

Aldosterone secretion stimulated by:

Answer 14

1. Angiotensin II (from RAAS)
2. Renin (low Na delivery to distal conv. tubule)
3. SNS activity
4. K+ & ACTH

Question 15

Effects of Cortisol

Answer 15

1. metabolic: promote gluconeogen & liver glycogen storage
   
   • -> insulin resistance, weight gain (stim. appetite)
2. anti-inflammatory
3. mineralcorticoid (retain Na+)

Question 16

Effects of aldosterone

Answer 16

1. retain Na+ (mineralcorticoid)

2. increase excretion of K+ & H+ (in urine)

Question 17

effects of DHEA

Answer 17

1. maintains axillary & pubic hair,
   * normal levels decrease w/ increasing age
   * deficit => female virilization

Question 18

Adrenal insufficiency (Dx, Tx)

Answer 18

= cortisol deficit
Dx: ACTH stim test (<18)
Tx: Cortisol

Question 19

Primary vs. Secondary adrenal insufficiency

causes & signs

Answer 19

Primary: adrenalitis, TB, carcinoma met or adrenal hemorrhage
- high ACTH, low cortisol; hyperpigmentation.
Secondary: pituitary trauma/postpart. apoplexy, tumor/radiation
- low ACTH & cortisol; pallor.

Question 20

Cushing’s Syndrome (causes, Sx)

Answer 20

Excess cortisol;
Causes: adrenal adenoma/carcinoma, ACTH-prod. pituitary tumor
Sx: weight gain/round face, HTN, amenorrhea, hirsutism, growth retardation (in kids only)

Question 21

Cushing’s Syndrome Dx & Tx

Answer 21

= excess cortisol.
Dx:
- Screen: bedtime salivary cortisol, 24 hr urine free cortisol, overnight dexamethasone suppression test (am plasma cort.>2)
- Localize: plasma ACTH, high dose dexameth. suppression test
Tx:
- surgery (adrenal tumor) - pasireotide (pit. tumor)
- decrease dose (exog. glucocorticoids)

Question 22

primary hyperaldosteronism

Answer 22

excess aldosterone production ==> HTN
Causes: adrenal adenoma or bilat adrenal hyperplasia (rare)
Dx: plasma Aldosterone/Renin activity RATIO >30
Tx: surgery (if adenoma), Spironolactone (if hyperplasia)

Question 23

Congenital Adrenal Hyperplasia

Answer 23

bc 21-hydroxylase deficiency => Low cortisol synth.
Dx: serum 17-hydroxyprogesterone
Tx: replacement doses of cortisol (or prednisone, dexamethasone)

Question 24

Pheochromocytoma

Answer 24

tumor of adrenal medulla that secretes catecholamines Sx: SNS activation -- tremor, high HR, palpitations, sweating, etc. Dx: urine or plasma metanephrines Tx: surgical excision

Question 25

Familial combined hyperlipidemia

Answer 25

excess ApoB produced by liver => varied presentation in family & individual over time (high TG, high cholesterol OR both)

Question 26

Familial hypercholesterolemia

Answer 26

AD => LDL R mutation bc over-expressed enzyme High risk: severe hypercholesterolemia, tendinous xanthomas, atherosclerosis

Question 27

familial hypertriglyceridemia

Answer 27

defective ApoC or deficit of LPL (lipoprotein lipase) | --> strong familial trend of high TGs

Question 28

Remnant Disease

Answer 28

defective ApoE = reduced clearance by remnants & LDL Rs

Question 29

physical exam signs of hyperlipidemia (5)

Answer 29

- corneal arcus (choles., age milky retinal blood vessels) | - central obesity

Question 30

how to Dx hyperlipidemia

Answer 30

fasting TG and LDL, HDL, & total cholesterol... a) TG < 400: LDL = total - (HDL + TG/5) (*TG/5 = VLDL) b) TG > 400: non-HDL chol. = total - HDL * refer to treatment guidelines for Dx values

Question 31

When to start treatment for hyperlipidemia

Answer 31

Start treatment with a statin IF... a) known CV disease b) LDL =190+ c) LDL = 70-189 & DM & age 40-75 d) LDL = 70-189 & 10 yr CV risk > 7.5% (no DM)

Question 32

Drugs that cause overproduction of lipids

Answer 32

- EtOH - diuretics - beta blockers - steroids - retinoic acid - HIV drugs

Question 33

Diseases that associated with secondary hyperlipidemia

Answer 33

Over-production: diabetes, liver disease, nephrotic syndrome | Under-excretion: Renal failure, hypOthyroidism

Question 34

ApoE (where? why?)

Answer 34

``` on remnants (not LDLs), = LDL remnant R ligand *mutated in Remnant Disease ```

Question 35

ApoCII (where, why?)

Answer 35

on chylomicrons coming from liver, = LPL cofactor! (needed for breakdown) *mutated in familial HyperTGemia

Question 36

ApoB100

Answer 36

on liver LDLs, 1 ApoB per particle OTHER than HDL => if high = high # particles; low = fewer, large particles. *mutated in familial hyperCHOLesterolemia

Question 37

ApoA1

Answer 37

on HDLs | --> tag for heading back to liver for recycling