Wk 6: Endocrine highlights

Question 1

What hormones come from the posterior pituitary?
What abt the anterior?

Answer 1

1) Posterior: Oxytocin + Antidiuretic hormone (ADH)
2) Anterior:
Growth Hormone (GH)
Adrenocorticotropic hormone (ACTH)
Luteinizing hormone (LH)/Follicle-stimulating hormone (FSH)
Prolactin (PRL)
Thyroid-stimulating hormone (TSH)

Question 2

An increase in serum osmolarity detected by hypothalamic osmoreceptors or decrease in blood volume can both trigger what?

Answer 2

ADH release

Question 3

What stimulates water reabsorption?

Answer 3

ADH

Question 4

List 3 Disorders Involving Antidiuretic Hormone (ADH)

Answer 4

1) Diabetes insipidus (DI):
2) Primary (psychogenic) polydipsia:
3) Syndrome of inappropriate secretion of ADΗ (SIADH):

Question 5

List 2 ways to differentiate ADH disorders

Answer 5

1) ADH stimulation test (aka “vasopressin challenge test”, water deprivation test)
-Used to differentiate neurogenic (central) diabetes insipidus vs nephrogenic diabetes insipidus
2) Serum ADH level

Question 6

Measuring _________ gives a more accurate reflection of GH than directly measuring GH does

Answer 6

IGF-1

Question 7

“___________” Cushing syndrome refers to increased cortisol production by the adrenal cortex

Answer 7

Endogenous

Question 8

~25% of endogenous Cushing syndrome is due to autonomous cortisol production by adrenal cortex; is this primary or secondary?

Answer 8

ACTH-independent; primary

Question 9

1) ~____% of endogenous Cushing syndrome is due to excessive ACTH secretion (ACTH-dependent, secondary)
2) 90% of these are due to what?

Answer 9

1) 75%
2) Cushing “disease” (2nd most common form overall after iatrogenic)

Question 10

Cushing syndrome diagnosis is established when at least _____ different first-line tests are unequivocally abnormal and cannot be explained by other conditions

Answer 10

2

Question 11

There are ____ first-line tests for diagnosis of Cushing Syndrome used in combination; diagnosis is est. with at least 2

Answer 11

3

Question 12

Describe the cortisol levels in the 3 Cushing tests in both healthy pts and ppl with Cushing Syndrome

Answer 12

1) Overnight low-dose dexamethasone suppression test (DЅТ)
-Normal low, Cushing high
2) Late-night salivary cortisol
-Normal low, Cushing high
3) 24-hour urinary free cortisol (UFC) excretion
-Normal normal, Cushing high

Question 13

1) You should measure what to differentiate ACTH-dependent vs. ACTH-independent Cushing syndrome?
2) What indicates an adrenal source

Answer 13

1) Plasma ACTH (and DHEAS)

Question 14

1) ACTH (and DHEAS) tests differentiate what in Cushing syndrome?
2) What does ACTH independent mean?
3) What does ACTH dependent mean?

Answer 14

1) ACTH-dependent vs. ACTH-independent
2) Low ACTH, low DHEAS = ACTH-independent
3) High ACTH, high DHEAS = ACTH-dependent

Question 15

1) If ACTH-dependent Cushing’s, you should differentiate between what two forms?
2) How is this done?

Answer 15

1) Pituitary vs. non-pituitary (ectopic) source
2) High-dose (8 mg) DST:
cortisol low (suppressed) in early morning= pituitary source
cortisol high (not suppressed) = ectopic source

Question 16

What are the two main etiologies of hypocortisolism?

Answer 16

1) Addison disease (primary adrenal insufficiency) and
2) Central adrenal insufficiency

Question 17

Most common causes of central adrenal insufficiency are prolonged ___________ use of glucocorticoids or ___________

Answer 17

exogenous; opiates

Question 18

Primary adrenal insufficiency (Addison disease): caused by dysfunction or absence of the ______________

Answer 18

adrenal cortices

Question 19

Cortisol deficiency:
1) How do you verify cortisol deficiency?
2) What should you measure to differentiate primary vs. central etiology? How do you interpret the results of this?

Answer 19

1) Low cortisol [early morning serum]
2) ACTH [early morning plasma]
High ACTH = primary
Low ACTH = central

Question 20

Cortisol deficiency:
1) What do you need to do if you know it’s primary?
2) What are the results of this?

Answer 20

1) Confirm dx w. cosyntropin stimulation test
2) Healthy pt: cortisol rises significantly
Primary Adrenal insufficiency: cortisol does not rise significantly (adrenals unable to respond to stimulus)

Question 21

LH surge indicates what?

Answer 21

ovulation (day of highest fertility)

Question 22

PRL can monitor what?

Answer 22

PRL-secreting pituitary adenomas

Question 23

1) Thyroid panel usually includes what 3 things?
2) Which two are used to differentiate hypothyroidism from hyperthyroidism, and primary vs. secondary causes of each.

Answer 23

1) TSH, free T4, and T3
2) TSH and free T4 (+/- T3)

Question 24

What are the two causes of hypothyroidism? What does each look like?

Answer 24

1) Primary: low T4/T3 > high TRH/TSH
-thyroid ablation, thyroid agenesis, congenital hypothyroidism
2) Secondary: low TRH and/or TSH > low T4/T3
-trauma, tumor, infarction

Question 25

What is:
1) The best initial screening test (most sensitive) for evaluation for primary hypo- and hyperthyroidism?
2) The best test for monitoring T4 replacement therapy? (e.g., in treatment of hypothyroidism)

Answer 25

TSH

Question 26

1) High PTH indicates what?
2) What abt low PTH?

Answer 26

1) Hyperparathyroidism
2) Hypoparathyroidism

Question 27

HbA1c can be used to determine average blood glucose level over how long?

Answer 27

the past ~4 months (100-120 days)

Question 28

DM can be diagnosed in a patient with classic symptoms of ________________________ + random plasma glucose ≥200 mg/dL.

Answer 28

hyperglycemia (polydipsia, polyuria, etc.)

Question 29

Routine screening for GDM performed with OGTT between __________________ gestation (for pregnant women not previously diagnosed with diabetes)

Answer 29

24-28 weeks