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Endocrine Exam 1 > Directed Study > Flashcards

Directed Study Flashcards

1
Q

What can lead to a secondary adrenocortical insufficiency (thus decreasing secretion of cortisol and adrenal androgens)?

A

ACTH Deficiency

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2
Q

What is ACTH excess?

A

Adrenal hyperfunction (Cushing Syndrome)

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3
Q

Is plasma ACTH a reliable indicator of pituitary function?

A

NO- It has a short plasma half life with episodic secretion

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4
Q

What does plasma ACTH have to be measured with to differentiate primary versus secondary adrenocortical insufficiency?

A

Simultaneous measurement of cortisol secretion

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5
Q

Why are basal cortisol levels generally unreliable?

A

They are low in the afternoon and evening (no value for diagnosis) and have a normal diurnal rhymthm

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6
Q

When should plasma cortisol be taken?

A

8AM

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7
Q

What is considered a deficiency of plasma cortisol?

A

Uner 5 ug/dL (lower it is, the more suggestive)

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8
Q

What level of plasma cortisol is not a deficiency and can virtually exclude diagnosis?

A

Over 20ug/dL

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9
Q

When should salivary coritsol be taken?

A

8AM

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10
Q

What is considered a deficiency for salivary cortisol?

A

Under 1.8 ng/mL

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11
Q

What level is considered not a deficiency of salivary cortisol and reduces the possibility of diagnosis?

A

Over 5.8 ng/mL

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12
Q

What is needed to diagnose secondary adrenal insufficiency (ACTH hyposecretion)?

A

Provacative testin (adrenal stimulation)

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13
Q

What is given in provactive testing to stimulate the adrenal?

A

Cosyntropin (a synthetic ACTH analogue)

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14
Q

After administration of cosyntopin, what is the normal cortisol response within 30 minutes?

A

Over 18-20 ug/dL

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15
Q

True or False: Stimulation of the adrenal gland with cosyntropin evaluates the ability of the HPA axis to respond to stress?

A

FALSE

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16
Q

What is considered a suboptimal response to cosyntopin, confirming adrenocortical insufficiency?

A

Under 20 ug/dL

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17
Q

When is evaluation of pituitary ACTH reserve unnecessary?

A

If cortisol response to rapid ACTH is subnormal (under 20 ug/dL) –> Adrenocortical insufficiency

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18
Q

What are 3 ways to evaluate pituitary ACTH reserve?

A
  1. Insulin-induced hypoglycemia
  2. Metyrapone Administration
  3. CRH stimulation
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19
Q

What must be achieved in insulin-induced hypoglycemia?

A

Blood glucose under 40 and patient should experience adrenergic symptoms like diaphoresis, tachycardia, weakness, and headache

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20
Q

In an insulin-induced hypoglycmiea test, what indicates normal ACTH reserve?

A

Plasma cortisol increases less than or equal to 20ug/dL

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21
Q

What are contraindictations to insulin-induced hypoglycemia test?

A

Elderly, cerebrovascular disease, cardiovascular disease, seizure disorder

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22
Q

If you suspect diminished adrenal reserve, waht would you prevede the insulin-induced hypoglycemia test with?

A

ACTH stimulation test

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23
Q

What 2 things does metyrapone administration do?

A

Inhibits P450c11 and interrupts negative feedback on HPA

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24
Q

What is p450c11?

A

11B-hydroxylase, which catalyzes the final step of cortisol synthesis

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25
Q

What does metyrapone administration result in?

A

Compensatory increase in ACTH

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26
Q

How is the compensatory increase in ACTH detected with metyrapone administration?

A

As increased precursor steroid, 11-deoxycortisol in plasma

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27
Q

What type of testing is preferred with metyrapone administration?

A

Overnight test (30mg/kg at midnight)

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28
Q

In a healthy individual, 11-deoxycortisol should raise to what the following morning after metyrapone administration?

A

Less than or equal to 7ug/dL

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29
Q

If there is suspected adrenal insufficiency, what should the metryapone administration test be preceded with?

A

ACTH stimulation test

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30
Q

What is given in the CRH stimulation test?

A

IV ovine CRH

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31
Q

True to False: CRH stimulation is less useful than insulin-induced hypoglycemia or metyrapone test for partial secondary adrenal insufficiency

A

TRUE- It overlaps with normal

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32
Q

In a health person when should peak ACTH and cortisol response be after CRH stimulation?

A

ACTH: 15 minutes
Cortisol: 60 minutes

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33
Q

In primary adrenal insufficiency, what is seen with CRH stimulation?

A

Elevated basal ACTH and exaggerated response to CRH

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34
Q

In secondary adrenal insufficiency with pituitary corticotroph destruction, what is seen after CRH stimulation?

A

Absent ACTH response

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35
Q

In secondary adrenal insufficiency with hypothalamic dysfunction, what is seen after CRH stimulation?

A

Prolonged and augmented ACTH response, delayed peak

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36
Q

What is the imaging procedure of choice for the hypothalamus and pituitary?

A

MRI

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37
Q

Why is MRI better than CT for imaging of the hypothalamus and pituitary?

A

Better definition of normal structures and hight resolution

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38
Q

What planes is MRI imaging of the hpothalamus and pituitary done in?

A

Sagittal and coronal

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39
Q

What type of contrast is used for MRI of hypothalamus and pituitary?

A

Gadolinum (heavy-metal)

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40
Q

What is the most commong cause of hypothalamic-pituitary dysfunction?

A

Pituitary adenoma

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41
Q

Are most pituitary adenomas hyper or hypo secreting?

A

Hyper

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42
Q

Who do you see pituitary adenomas that secrete epinephrine?

A

Adults (rare in children)

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43
Q

What is the most common hormone secretion from a pituitary adenoma?

A

Prolactin

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44
Q

What is an intrasellar adenoma that is under 1cm in diameter with no sellar enlargment or extrasellar extension?

A

Microadenoma

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45
Q

What constitutes a macroadenoma?

A

Over 1cm in diameter and may extend suprasellar, into sphenoid sinus or lateral extension

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46
Q

What is the most frequent endrocrinologic abnormality and earliest symptom of a pituitary adenoma?

A

Hypogonadism

47
Q

What causes hypogondadism?

A

Reduced GnRH

48
Q

What does reduced GnRH result in?

A

Reduced FSH and LH

49
Q

What causes primary gonadal failure?

A

Elevated FSH and LH

50
Q

What things have a negative feedback on paraventricular neurons releasing GnRH?

A

Prolactin, GH, ACTH, and cortisol

51
Q

What decreases anterior pituitary sensitivity to GnRH?

A

Prolactin

52
Q

What causes acromegaly?

A

Hypersecretion of GH

53
Q

Hypersecretion of ACTH results in what?

A

Cushing Syndrome

54
Q

What are late manifestations of pituitary adenomas?

A

HA, visual loss (large tumors, due to suprasellar extension)

55
Q

What visual defects are seen in pituitary adenomas?

A

Bitemporal hemianopsia (optic chiasm)

-If you see this, it is pituitary/hypothalamic disorder until proven otherwise)

56
Q

If your patient has diplopia, what has happened?

A

Pituitary adenoma has extended into the cavernous sinus, affecting CN III, IV, VI

57
Q

If a child has short stature, what might you suspect?

A

GH deficiency…. this is most frequent presentation of hypothalamic-pituitary dysfunction

58
Q

That is treatment for pituitary adenoma?

A

Surgery, irradiation, or drugs to suppress hypersecretion or growth

59
Q

What is the most common hypersecreting pituitary adenoma?

A

Prolactinoma

60
Q

What does a prolactinoma cause in men?

A

Impotence, decreased libido

61
Q

What does a prolactinoma cause in women?

A

Glactorrhea, amenorrhea

62
Q

How do you diagnose prolactinoma?

A

MRI, PRL levels

63
Q

Who do you measure PRL levels in?

A

Patients presenting with glacatorrhea, sellar enlargement, gonadal dysfuncion, amenorrhea, infertiliy, decreased libido, impotence

64
Q

What is seen on histology with a prolactinoma?

A

Chromophobic, small and uniform, round/oval nuclei and scant cytoplasm, diffuse capillary network in stroma

65
Q

What is done for treatment for prolactinoma?

A
  1. Dopamine agonist: Bromocriptine/Cabergoline
  2. Surgery: Transsphenoidal, microsurgery
  3. Radiotherapy: Persistent hypoerprolactinemia and not responded to surgery or dopamine agonists
66
Q

What is the DOC for prolactinoma that is administeres 1-2 times/week and has a better SE profile than bromocriptine?

A

Cabergoline

67
Q

What does cabergoline do?

A

Reduces microadenoma size and PRL levels

68
Q

Who do you have to be careful in giving caergoline to?

A

Parkinsons disease patients receiving treatment- Risk of cardiac valve (need echo if long term treatment indicated)

69
Q

Who do you see empty sella syndrome in?

A

Middle-aged obese women

70
Q

What are some associations with empty sella syndrome?

A

Systemic HTN and benign intracranial HTN

71
Q

What is the etiology of empty sella syndrome?

A

Subarachnoid space extends into the sella turcica (partial filling with CSF)

72
Q

What does the subarachnoid space extending into the sella turcica lead to?

A

Remodeling and enlargement of sella with flattening of the pituitary

73
Q

What causes primary empty sella?

A

Congential incompetence of diaphragma sellae

74
Q

What are other causes of empty sella?

A

Pituitary surgery, radiation therapy, postpartum pituitary infarction (Sheehan syndrome), subclinical hemorrhagic infarction (PRL-/GH-secreting adenomas)

75
Q

What is seen clinically with empty sella syndrome?

A

Uncommon.. but HA, CSH rhinorrhea, visual field impairment

76
Q

How do you diagnose empty sella syndrome?

A

MRI

77
Q

What is the % success for convential irradiation therapy for acromegaly?

A

60-80%

78
Q

If supervoltage irradiation used for acromegaly?

A

NO…the GH levels take 10-15 years to normalize and there are severe consequences

79
Q

What are the severe consequences of supervoltage irradiation?

A

Hypopituitarism, hypothyroidism, hypoadrenalism, hypogonadism

80
Q

What is the success rate of gamma knife surgery for acromegaly?

A

50-70% at 2 years following therapy

81
Q

What can radiotherapy cause in Cushing’s Syndrome?

A

Loss of pituitary function in over 50% of patients and visual defects (due to damage to the optic chiasm or cranial nerves)

82
Q

What is the % success rate for conventional radiotherapy for Cushing’s?

A

55-70% remission at 1-3 years

83
Q

What is the % remission seen with gamma knife therapy for Cushing’s?

A

65-75% remission at 1-3 years

84
Q

Why is a single measurement of ACTH and adrenal hormones frequently unreliable?

A

ACTH and adrenal hormones

85
Q

What is normal plasma ACTH?

A

9-52 pg/mL

86
Q

In adrenal insufficiency (primary adrenal disease), what happens to ACTH levels?

A

ELEVATED

87
Q

In Cushing’s syndrome (primary glucocorticoid-secreting adrenal tumor), what happens to ACTH levels?

A

LOW (under 5 pg/mL)

88
Q

What happens to ACTH in congenital adrenal hyperplasia?

A

ELEVATED

89
Q

What happens to ACTH in Cushing disease (pituitary ACTH hypersecretion)?

A

ACTH is inappropriately normal or elevated

90
Q

What happens to ACTH in ectopic ACTH syndrome?

A

ACTH is markedly elevated

91
Q

What happens to ACTH in pituitary ACTH deficiency and secondary hypoadrenalism?

A

ACTH is normal or under 10pg/mL

92
Q

What 2 things can metyrapone testing do?

A
  1. Diagnose adrenal insufficiency

2. Assess pituitary-adrenal reserve

93
Q

What does metyrapone do?

A

Blocks cortisol synthesis by inhibiting 11B=hydroxylase, resulting in a buildup of 11-deoxycortisol)

94
Q

What does the reduction of cortisol syntehsis from metyrapone result in?

A

Increased ACTH (increases 11-deoxycortisol)

95
Q

What is a normal response, indicating normal ACTH secretion and adrenal function in a metyrapone test?

A

11-deoxycortisol over 7ng/dL

Plasma ACTH over 100 pg/mL

96
Q

What indicates adrenocorticol insufficiency with a metyrapone test?

A

11-deoxycortisol under 7ng/dL

97
Q

What is the rapid ACTH stimulation test?

A

Acute adrenal response to ACTH

98
Q

What does the rapid ACTH stimulation test diagnose?

A

Primary and secondary adrenal insufficiency

99
Q

What agent is used for the rapid ACTH stimulation test?

A

Cosyntropin (synthetic ACTH)

-Also teracosactin

100
Q

What are the steps in the procedure of the rapid ACTH stimulation test?

A
  1. Baseline cortisol obtained
  2. Cosyntropin administered (250 ug IM or IV)
  3. Plasma cortisol samples taken at 30/60 minutes
101
Q

What is a normal response to ACTH stimulation test?

A

Peak corisol over 18ug/dL

102
Q

With peak cortisol over 18ug/ML in the ACTH stimulation test, what does this exclude and what does it not rule out?

A
  • Excludes primary and overt secondary adrenal insufficiency
  • Doesn’t rule out partial ACTH deficiency (decreased pituitary reserve… need to test further with metyrapone, hypoglycemia, or CRH)
103
Q

What indicates adrenal insufficiecny with the ACTH stimulation test?

A

Peak cortisol under 18ug/dL

104
Q

What is seen in pituitary ACTH-dependent Cushing Syndrome?

A

Pituitary adenoma secreting ACTH with ELEVATED ACTH

105
Q

What is seen in pituitary ACTH-independent Cushing Syndrome?

A

Adrenal tumor, LOW/UNDETECTABLE LEVELS OF ACTH

106
Q

What does the overnight dexamethasone suppression test establish the presence of?

A

Cushing Syndrome

107
Q

What is dexamethasone and how does it work?

A

Potent glucocorticoid

-Suppresses pituitary ACTH release, reducing plasma/urine cortisol, reducing feedback inhibition

108
Q

What is done in the overnight dexamathasone suppression test?

A

1mg of dexamethason is given at 11PM, with plasma cortisol measured the folloing morning

109
Q

What is a normal serum/plasma cortisol level with the overnight dexamethasone suppression test?

A

Uner 1.8ug/dL

110
Q

If there is normal cortisol levels indicating that the dexamethasone suppression didn’t suppress cortisol, what is done?

A

High dose (8mg) test

111
Q

With the high dose dexamathasone suppression test, what indicates Cushing’s?

A

Plasma cortisol uner 50% baseline values and a high ACTH

112
Q

What is the diagnosis is the high dose dexamethasone suppression test fails to suppress cortisol levels (normal/elevated cortisol) and normal to elevated ACTH?

A

Ectopic ACTH syndrome

113
Q

What is seen in the high dose dexamethasone suppression test in a cortisol-producing adrenal tumor

A

Fails to suppress (normal to elevated cortisol) and low/undetectable ACTH

Endocrine Exam 1 (11 decks)

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