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Flashcards in Path Deck (62):
1

"Is the pt unable to make adequate amounts of this hormone?"

What test are we likely to perform?

Stimulation test

-Pt receives or does something that should raise levels of the hormone. If response is not adequate, dx is made.

2

"Is this pt unable to limit production of this hormone to what is appropriate?"

What test are we likely to perform?

Suppression test

-Pt receives or does something that should lower levels of the hormone. If response is not adequate, dx is made.

3

Thyroxine (T4) and tri-iodothyronine (T3) are produced in the thyroid gland.

What hormone (and from where) stimulates their production and secretion?

Thyroid stimulating hormone (TSH, thyrotropin) from the anterior pituitary

4

TSH production and secretion is stimulated by what (and from where)?

TSH releasing hormone (TRH) from the brain

5

Low T4 confirms:

HYPOthyroidism

6

Pts who are HYPOthyroid from thyroid dz will have high TSH. Why?

Loss of negative feedback on the pituitary

7

Pts who are HYPERthyroid from thyroid dz will have low TSH. Why?

Strong negative feedback on pituitary

8

Low T4, high TSH:

Hypothyroidism
-mimics depression, mental illness

9

High T4, low TSH:

Hyperthyroidism
-mimics anxiety, mental illness

10

Labs for 2° hypothyroidism:
Cause of 2° hypothyroidism:

Low T4, low TSH.

Pituitary does not produce adequate amount of TSH.

11

Labs for 2° hyperthyroidism:
Cause of 2° hyperthyroidism:

High T4, high TSH.

Overactive pituitary OR a tumor elsewhere producing excess TSH.

12

Anti-thyroid peroxidase Abs (anti-TPO) target an:

Iodine oxidizer

13

Anti-thyroglobulin Abs target the:

Colloidal storage form of thyroid hormone

14

Anti-TSH receptor Abs (anti-TR, "TRAbs") are often stimulatory and cause:

Hyperthyroidism

15

Cortisol from the adrenal cortex is the body's principal glucocorticoid.

Excess cortisol produces what syndrome?

Cushing's

16

Adrenal or pituitary dz with HYPOadrenocorticism:

Addison's
-Cannot stimulate cortisol production
-Mimics depression or anorexia nervosa

17

Adrenal or pituitary dz with HYPERadrenocorticism:

Cushing's
-Cannot suppress cortisol production
-Mimics mental illness and other common problems

18

Cortisol production by the adrenal cortex is stimulated by:

ACTH

19

A morning serum cortisol > __ ug/dL or a morning salivary cortisol > __ ug/mL basically excludes adrenal insufficiency.

What test would you perform?

Serum cortisol > 18 ug/dL
Salivary cortisol > 5.8 ug/mL

ACTH stimulation test.

20

What is expected in an ACTH stimulation test in primary adrenal cortical insufficiency (due to dz of the gland itself)?

Cortisol levels won't rise despite ACTH administration.

21

Auto-Abs detected in autoimmune adrenalitis:

Anti-21-hydroxylase Abs

22

Plasma ACTH LOW
Aldosterone LOW
Renin HIGH

Dx:

Primary adrenal insufficiency
(adrenal gland problem)

23

Plasma ACTH LOW
Aldosterone NORMAL
Renin NORMAL

Dx:

Secondary adrenal insufficiency
(pituitary problem)

24

In suspected hyperadrenocorticism, screen with:

24 hour urinary cortisol
(Cushing's pts have > 3x the upper limit of ref range)

25

For borderline hyperadrenocorticism, what test is used?

Dexamethasone suppression test

26

Explain dexamethasone suppression testing.
If cortisol is still high:
If ACTH is still high:

Pt is given 2mg of dexamethasone...
If cortisol is still high, 1° or 2° hyperadrenocorticism is likely.
If ACTH is still high, it is likely 2° (comes from pituitary).

27

Too much aldosterone is responsible for:
How is it screened?
Consider screening pts with: (3)

Hypertension
Screened through spot plasma aldosterone + plasma aldosterone / renin ratio (both will be high).
Consider screening pts with hypokalemia, severe refractory HTN, or a known adrenal tumor.

28

Low aldosterone is familiar as:

Renal tubular acidosis, type IV

29

Low usable levels of growth hormone before closure of the epiphyses results in:

High levels produces _________ in children/teens and _________ in adults.

Low GH >> Permanent short stature (i.e., dwarfism)

High GH >> GIGANTISM in children/teens, ACROMEGALY in adults.

30

How is GH measured?

IGF-1 in the liver

31

To screen for acromegaly, measure:

Serum IGF-1

32

Acromegaly is most often caused by:

Pituitary adenoma

33

IGF-1 and IGFBP-3 are both low in deficiency of:

hGH

34

-Children who grow up in a neglectful/non-nurturing environment produce insufficient hGH and develop short stature as a result. Remember this when working up "pituitary GH deficiency."
-When removed from environment, pts exhibit catch-up growth.

Dx:

Psychosocial dwarfism

35

Prolactin is produced in the pituitary in response to absence of:

Dopamine
(inhibits production and secretion of prolactin)

36

-Woman with galactorrhea / amenorrhea or who doesn't have a normal cycle
-Loss of libido, infertility, "trouble seeing"

High values (> 10x the top of ref range) suggest:

Prolactinoma

37

-Released from posterior pituitary
-Allows reabsorption of water by renal collecting ducts

ADH (aka vasopressin)

38

Too little ADH.
Clinical syndrome is:

Diabetes insipidus
(polyuria without glycosuria, SG < 1.020)

39

The distinction between pituitary and nephrogenic diabetes insipidus is usually made by injecting:

Desmopressin (synthetic ADH)

40

Too much ADH (SIADH) usually results from: (2)
Pts have low levels of:

-Ectopic ADH secretion by a tumor, often oat cell lung cancer
-Porphyria (from the brain)

Low sodium (pt is hyponatremic)

41

Abnormal serum calcium levels on routine screening and/or passing a calcium kidney stone should raise suspicion for:

Hyperparathyroidism

42

Dx of hyperparathyroidism is based on:

Elevated serum PTH

43

When low calcium levels are detected, screen for:

Hypoparathyroidism
-DiGeorge syndrome – no parathyroids
-Autoimmune parathyroiditis
-Post-thyroid surgery

44

The best known marker for type I diabetes is Abs against:

Gamma-glutamyl decarboxylase

45

Pts with hypoglycemia, measure: (2)

-Insulin
-C-peptide (production accompanies production of insulin)

46

-Pts appear anxious
-Intermittent or persistent HTN
-Sweating attacks
-Severe headaches

Dx:

Pheochromocytoma

47

Best screen for pheochromocytoma:

24 hour urinary fractionated catecholamines and metanephrines

48

-Common origin = adrenal medulla
-Increased dopamine and/or homovanillic acid (HVA) and vanillylmandelic acid (VMA) in urine

Neuroblastoma

49

-Ulcers and/or diarrhea prompt consideration for:
-Caused by:

Zollinger-Ellison syndrome
Caused by an endocrine tumor in the pancreas or duodenum producing excess gastrin (gastrinoma)

50

Elevated gastrin levels are also seen in:

-Achlorhydria from dz (atrophic gastritis)
-Meds (antacids)

51

What stimulates the release of gastrin from gastrinomas but suppresses it from normal G-cells?

Secretin

52

What is the marker in medullary thyroid cancer?

Calcitonin

53

-Wheezing, flushing, diarrhea

Think...

Carcinoid syndrome

54

Carcinoid syndrome is due to production of _________ by the tumor.

Carcinoid syndrome is due to production of SEROTONIN by the tumor.

55

A screen for carcinoid is:

5-hydroxy-indole acetic acid (major metabolite of serotonin) in urine

56

-Boy who doesn't undergo puberty when it's time
-Grown man who is troubled by infertility, erectile dysfxn, or "loss of energy"

What is ordered?

Serum testosterone, FSH and LH levels

57

-Often unrecognized XXY
-Testosterone is low
-FSH and LH are high

1° hypogonadism

58

-Problem is in the brain / hypothalamus
-Most often "idiopathic"
-Testosterone, FSH and LH are all low

2° hypogonadism

59

-Pituitary adenomas (usually prolactinomas)
-Parathyroid adenomas / hyperplasias
-Pancreatic endocrine tumors (gastrinomas, etc)

Think...

MEN-I

60

-Caused by mutated RET
-Features medullary thyroid cancer and pheochromocytomas

Think...

MEN-II

61

-Mutant RET
-Parathyroid adenomas / hyperplasias

MEN-IIa

62

-Mutant RET
-Marfanoid habitus
-Mucosal neuromas

MEN-IIb