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Foundations III- Endocrine > Hypothalamus and Pituitary I/II > Flashcards

Hypothalamus and Pituitary I/II Flashcards

1
Q

where is the pituitary gland located?

A

sits in the sella turcica of the sphenoid bone

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2
Q

The pituitary gland is separated into which 3 lobes?

A

anterior
intermediate
posterior

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3
Q

the normal pituitary gland is made up of the anterior and posterior parts called…?

A 
Ant = Adenohypophysis
Post = Neurohypophysis
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4
Q

what hormones are secreted by the posterior pituitary gland?

A

oxytocin

ADH - “bright” spot on MRI

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5
Q

what hormones are secreted by the posterior pituitary gland?

A 
TSH
ACTH
FSH and LH
GH
Prolactin
endorphins
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6
Q

what is one major difference between anterior and posterior gland hormone secretion?

A

anterior pit. - indirect control through release of regulatory hormones

poster pit. - direct release of hormones

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7
Q

what hormones are secreted by the intermediate lobe of the pituitary?

A

endorphins cleaved from pre-opiomelanocortin (POMC) which gives ACTH and beta-endorphin

MSH (melanocyte-stimulating hormone)

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8
Q

GnRH stimulates which hormones in the ant pituitary?

A

FSH and LH

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9
Q

GHRH stimulates which hormones in the ant pituitary?

A

GH

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10
Q

SS inhibits which hormones in the ant pituitary?

A

GH and TSH

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11
Q

TRH (thyrotropin releasing hormone) stimulates which hormones in the ant pituitary?

A

TSH and prolactin

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12
Q

Dopamine inhibits which hormones in the ant pituitary?

A

prolactin

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13
Q

CRH stimulates which hormones in the ant pituitary?

A

ACTH, MSH, endorphins

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14
Q

what sources can you test to measure hormones?

A
  1. Capillary puncture
  2. Venipuncture
  3. Arterial stick
  4. Urine specimens (clean catch)
  5. 24 hr urine
  6. tissue bx (thyroid)
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15
Q

what are you measuring using the 24hr urine sample and for what condition?

A

catecholamines and metabolites for pheochromocytoma

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16
Q

Types of Testing available in Endocrinology

A

Hormone levels (direct, free, total, antibodies, precursor, ratios), Suppression tests, Stimulation tests, Imaging tests, Biopsies

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17
Q

How are hormones w/longer half lives and not bound by proteins measured?

A

directly with a random test (ie. TSH)

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18
Q

How are hormones bound to proteins measured?

A

Measure free and total fractions (ie Total T4 and free T4)

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19
Q

Precursor hormone levels examples? what is it used to evaluate for?

A

Androstenedione, prohormone for estrogen and testosterone

hyperadrenergic states

  • congenital adrenal hyperplasia
  • ovarian hyperplasia or tumor
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20
Q

What hormone ratio can be measured for infertility?

A

FSH:LH ratios

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21
Q

when should you measure cortisol levels?

A

Perform first venipuncture between 6 and 8 AM

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22
Q

what factors affect the timing of certain hormone level testing?

A

Pulsatile/episodic
Shorter half lives
Measure hormones at particular times of the day OR
24 hour urine collection methods

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23
Q

How do you gather information about feedback loops for hormone levels?

A

Measure the precursor hormone and the end product of that hormone’s action

ie.
TSH and T4
PTH and calcitrol

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24
Q

when are suppression tests used to measure hormone levels?

A

when HYPERfunction of the gland is suspected

ie. pt has excess cortisol

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25
Q

what is an example of a suppression test?

A

Dexamethasone suppression test (synthetic glucocorticoid)

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26
Q

when can you do a stimulation test?

A 
suspected HYPOfunction
(low cortisol)
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27
Q

example of stimulation test?

A

ACTH Stimulation test

Test adrenals response to synthetic ACTH

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28
Q

What are disorders of the hypothalamus?

A

Tumors (ie. craniopharyngioma)
Inflammation ( lymphocytic hypophysitis)
Metastatic tumor (breast, lung)
Infiltration (sarcoidosis, histiocytosis, hemochromatosis)

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29
Q

what are disorders of the hypothalamaus often asoc. with??

A

loss of posterior pituitary function

i.e central diabetes insipidus

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30
Q

Vasopressin MOA

A

V-1 a receptors mediate pressor activity

V-1b or V-3 receptors modulate ACTH secretion

V-2 receptors mediate renal handling of water excretion and promote coagulation factor VIII action

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31
Q

Where are the baroreceptors that stimulate ADH?

A

carotids

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32
Q

Vasopressin V-2 agonists uses which hormone?

A

Antidiuretic Hormone – ADH

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33
Q

How does Vasopressin use ADH?

A

to decrease water excretion in central diabetes insipidus and nocturnal enuresis

also, increase circulating levels of factor VIII and improve platelet responsiveness

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34
Q

what is diabetes insipidus?

A

Inability of the kidney to concentrate urine with passage of copious and inappropriate volumes of dilute hypotonic urine

polyuria and often polydipsia

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35
Q

What med can you give to tx central diabetes insipidus and how does it work?

A

desmopression = can dramatically decrease UO and corrects high Na and osmolarity

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36
Q

what is the problem in central diabetes insipidus, Na or water?

A

WATER

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37
Q

Causes of central diabetes insipidus?

A

Idiopathic: 30 – 50%

CNS/pituitary surg, trauma, anoxic encephalopathy

Primary tumors, craniophyrngioma, suprasella germinoma, pinealoma

Metastatic tumors (leukemia and lymphoma)

Granulomatous Disease

Hereditary (Autosomal dominant)

Pregnancy

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38
Q

How can you screen for Central diabetes insipidus?

A

screen w/ 24 hr urine collected by the pt

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39
Q

pregnancy can cause which types of central diabetes insipidus?

A

partial central diabetes or nephrogenic insipidus

d/t markedly increased levels and activity of vasopressinase (oxytocinase)

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40
Q

Presentation of Central Diabetes Insipidus?

A

after brain surg or significant brain injury (anoxia, trauma, hemorrhage)

acute w/ unremitting sustained thirst and polyuria

preference for cold liquids esp. water w/ continued thirst and polyuria day & night

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41
Q

what 2 things are found in DM and central diabetes insipidus? and how can you distinguish btwn the 2 conditions?

A

polyuria
polydipsia

order a glucose to make sure not DM (also Ca, K, Cr)

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42
Q

how can you dx Central Diabetes Insipidus?

A

“Water Deprivation Test” aka Dehydration Test

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43
Q

what can you expect to see on a water deprivation test?

A

Expect S(sodium) and S(osm) to be high end of ref range or high at start

W/ fluid deprivation U(osm) plateaus w/ significant rise after Desmopresin (ADH analog) injection

ADH is not high

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44
Q

Nephrogenic diabetes insipidus

A

No response to Desmopressin injection

Plasma ADH is elevated before and after dehydration

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45
Q

Primary polydipsia (PPD)

A

Serum(Na) and S(osm) may be mid range or low-normal at start

in CDI thirst improves but in PPD it does not

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46
Q

How can you tx neurogenic (central) DI?

A

Primarily aimed at decreasing urine output (increase ADH)

Replacement of fluid losses is also important
- hypernatremia can occur if thirst is impaired or the patient has no access to water

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47
Q

what is the problem in central DI?

A

deficient secretion of ADH

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48
Q

How does desmopressin (DDAVP) work on central DI?

A

Potent anti-diuretic –>

reduces nocturia, providing adequate sleep; control of diuresis during the day

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49
Q

which form of Desmopression is more potent?

A

Nasal form&raquo_space; oral

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50
Q

if pt has incomplete response to desmopressin what are alternative meds??

A

Chlorpropamide
Carbamazepine (anti-szr)
Clofibrate (hyperlipidemia)

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51
Q

what is the problem in nephrogenic DI?

A

resistance of the kidneys to the effects of ADH

no response to DDVAP

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52
Q

DI and SIADH: where is the water and where is the sodium?

A

DI: peeing a lot of water, hypernatremia (Decreased serum sodium and osmolality)

SIADH: retaining lot of water, hyponatremia

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53
Q

What is the clinical hallmark of ADH?

A

HYPONATREMIA

(<135 meq) without evidence of relative water excess

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54
Q

MC of adult nephrogenic DI?

A

chronic lithium use or hypercalcemia

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55
Q

39

A

39

56
Q

what is the tx for nephrogenic DI?

A

Thiazide diuretic in combination with a low salt diet

57
Q

40

A

40

58
Q

Inappropriate ADH leads to

A

volume expansion due to water retention

Volume expansion over-rides sodium handling with inappropriate urinary sodium loss

59
Q

SIADH acute vs. chronic

A

Acute is documented to be < 24 hrs

Chronic is >24hrs or not documented < 24 hrs

60
Q

Causes of SIADH?

A

Ectopic Production: malignancy

Baroreceptor Dysregulation: CNS, pulmonary, transient

Multifactorial (central and peripheral): drugs

61
Q

sxs of hyponatremia

A

Moderate/ severe: N w/out V, confusion, HA

Severe: V, somnolence, seizures, glascow scale <8

62
Q

44

A

44

63
Q

SIADH Tx

A

restrict fluid intake w/ gental administration of hypertonic fluids

64
Q

what is the problem of SIADH?

A

excess volume

65
Q

45

A

45

66
Q

Lesions: Craniopharyngioma

A

h

67
Q

What is the most frequent sellar tumor of childhood and adolescence?

A

craniopharyngioma (hypothalamic tumor)

68
Q

where do craniopharyngiomas arise from?

A

Rathke’s Pouch remnants that extend into the diencephalon during development

69
Q

Childhood presentation of craniopharyngioma?

A

growth retardation, pubertal delay, visual field loss, vomiting

70
Q

disorders caused by functional pituitary tumors?

A

Acromegaly (excess GH)

Pituitary dependant Cushing’s Disease (ACTH)

Prolactinomas w/ prolactin assoc. hypogonadism

Central hyperthyroidism d/t TSH secretion

71
Q

what anatomic damage can be caused by disorders of the pituitary?

A

Visual field loss, cranial nerve injury
Hypopituitarism
CSF leak
Diabetes insipidus : uncommon

72
Q

48

A

48

73
Q

49

A

49

74
Q

49

A

49

75
Q

50

A

50

76
Q

diffuse pituitary hyperplasia

????

A

Pregnancy

Prolonged Primary Hypothyroidism & Hypogonadism

GhRH secreting tumors

Somatomamatotropic Hyperplasia in Carney Complex

77
Q

Discrete pituitary tumor

A

54

78
Q

what should you measure to manage pituitary incidentaloma?

A

prolactin

79
Q

pituitary tumor manifestations?

A

Intrasellar

tumor assoc. loss (GH>LH>FSH>TSH>ACTH)

Suprasellar

Lateral Extension

Inferior Erosion

80
Q

how can pituitary hypothalamic lesions cause neurologic effects?

A

Tumor erosion with CSF leak

81
Q

clinical manifestations and prevalence of prolactinoma?

A

signs of increased prolactinoma

40-45%

82
Q

somatotroph adenoma clinical manifestation?

A

acromegaly

83
Q

corticotroph adenoma clinical manifestation?

A

cushing’s disease

84
Q

gonadotroph adenoma clinical manifestation?

A

compression sx hypopituitarism

85
Q

null cell clinical manifestation?

A

compression sxs

hypopituitarism

86
Q

thyrotroph adenoma clinical manifestation?

A

hyperthyroidism

compression sxs

87
Q

Main function of prolactin:

A

Mammary gland development (puberty)

Initiation of lactation postpartum (pregnancy)

88
Q

Secreted by lactotrophs of the anterior pituitary…

A

PROLACTIN in a pulsatile manner

89
Q

what is prolactin inhibited by?

A

hypothalamic Prolactin Inhibitory Factor (dopamine)

90
Q

prolactin suppresses ___ and lowers ___ which alters menses and fertility

A

GnRH

LH and FSH

91
Q

prolactin stimulates adrenal androgen production which promotes…

A

weight gain and hirsuitism mostly in women

92
Q

S/s of hyperprolactinemia in females

A 
Irregular menstruation (*amenorrhea)
*Infertility
Headache
Peripheral Vision Problems
Moods changes/ depression
*Galactorrhea
Menopausal symptoms
93
Q

S/s of hyperprolactinemia in males

A

*Impotence
*Infertility
Loss of libido
*Headache
*Peripheral Vision Problems
Moods changes/ depression
Galactorrhea
Gynecomastia

94
Q

Causes of increased prolactin

A

Increased lactotroph number or secretion (pregnancy and hypothyroidism**)

Decreased prolactin disposal

95
Q

what is the “stalk effect?”

A

2cm tumor is NOT prolatinoma;

dopamine effects decreased by stalk injury

96
Q

67

A

67

97
Q

67

A

67

98
Q

Fasting Serum Prolactin Levels should be measured in all pts w/??

what is included in a further w/u?

A

galactorrhea, gynecomastia and/or hypogonadism

MRI w/ and w/out contrast

99
Q

GH secreting tumors may also express….

A

D2 receptors

100
Q

Prolactin is under _____ control and predominant inhibitor is ______.

A

tonic inhibitory

Dopamine

101
Q

Macro and microademonas can be tx’d w/ what types of drugs?

A

dopamine agonists

102
Q

how soon after giving dopamine agonists for a macroademoa, will you see a detectable decrease in size?

A

w/in 24 hrs

103
Q

What is the 1st line medication for a prolactinoma?

A

dopamine agonist Nota Bene

104
Q

Etiologies of hyperprolactinemia?

A

Prolactinoma, other pituitary tumors, hypothalamic dz,
Chronic Kidney Failure,
cirrhosis or Liver Disease,
Spinal cord damage
Chest wall injury, severe Primary Hypothyroidism,
Anti-psychotic meds, radiation, Surgery, Idiopathic

105
Q

what test can you order to measure prolactin levels?

A

basal (fasting serum) PRL levels

106
Q

Which drugs can cause hyperprolactinemia?

A

Dopamine-receptor “antagonists”

Dopamine-“depleting” agents (methyldopa, reserpine)

INH, TCA’s, Verapamil, estrogens, antiandrogens, opiates

107
Q

What labs are included in a work-up of autonomous prolactinoma vs. other etiologies?

A 
Fasting PRL
FSH, LH
estradiol
testosterone
TSH
renal/hepatic panels
ß-hCG in females
108
Q

what imaging should you order for a prolactinoma work-up?

A

MRI of pituitary and brain

109
Q

T or F: most microadenomas progress to macroadenomas

A

FALSE.

do not!

110
Q

tx of microprolactinomas

A

Dopamine agonists – Bromocriptine twice daily with food

+/- surgical resection

111
Q

drug of choice for infertility or pregnant pt’s seen with abn. prolactin levels?

A

bromocriptine

112
Q

Nonpharmacologic tx options for prolactinemia and prolactinoma?

A

Transsphenoidal resection
Surgical resection
Radiation therapy

113
Q

Acromegaly is assoc. w/ hormone staining of?

A

GH +/-

prolactin

114
Q

when does GH peak?

A

w/in an hour after the onset of deep sleep

115
Q

GH secretion is controlled by what 2 factors?

A

hypothalamic and peripheral

GHRH releases
GHIH (somatostatin) inhibits

116
Q

when is IGF-1 produced?

A

in liver after stimulation by GH

117
Q

IGF-1 stimulates growth of…

A

epiphyseal plates of long bones

118
Q

what does absence of GH result in…

A

dwarfism (laron type)

119
Q

what are the 3 phases of post-natal growth and characteristics?

A

Infantile phase- 1st 2yrs of life

Childhood - relatively constant

Pubertal phase - effects of increasing gonadal steroids and GH secretion

120
Q

Constitutional short stature

A

2 SDs or more below the mean height for children of that sex and chronologic age

121
Q

Genetic short stature

A

Constitutional short stature in children of short parents

growth velocity is normal but consistently 3-5th percentile on growth curve

122
Q

pathologic causes of short stature?

A 
GH deficiency
Intrauterine growth retardation
Infections (rubella, CMV)
Maternal drug/alcohol usage
Genetic syndromes (Turner's syndrome)
Chronic systemic dz (Cancer, CF, renal insufficiency, GI dz)
Psychosocial dwarfism
123
Q

Diagnostic approach to short stature (3 steps)?

A

History and Clinical Presentation

IGF-1 Levels

GH Stimulation Tests

124
Q

H&P key finding for short stature?

A

slowed growth that progressively deviates from a previously defined growth percentile on growth curve

125
Q

does the child have any noticeable dysmorphic features or disproportionate short stature?

A

Chromosomal abnormalities
Intrauterine infections
Maternal exposures
Disproportionate short stature (rickets)

126
Q

Possible genetic factors or aspects in the child’s history that could lead to short stature?

A

Heights of relatives
Presence of health prob’s in the fam
H/o early/late puberty in fam members
Mom’s pregnancy, labor and delivery
Multiple measurements of the child’s ht and wt from birth
Child’s general health, nutritional state, past illnesses, injuries and stresses

127
Q

Does the child have growth failure?

A

Children should grow 5 cm per year from age 2 yrs until the onset of puberty

X-ray of the hand and wrist (compare bone development to ht and chronological age)

128
Q

If H&P suggest GH deficiency measure…

A

plasma IGF-1 level

Concentration of IGF-1 reflects the concentration of secreted GH

129
Q

Poor nutrition ___ IGF-1 despite normal levels of GH.

A

lowers

130
Q

low levels of IGF-1 in conditions other than GH deficiency include:

A

Hypothyroidism
Diabetes mellitus
Renal failure

131
Q

macroprolactinoma on imaging will touch…

A

the optic chiasm

132
Q

“Gold standard” in the diagnosis of GH deficiency

A

GH Stimulation Tests

if IGF-1 is low

133
Q

GH stimulation tests slide 98???

A

98

134
Q

etiology of GH deficiency

A

Hypothalamic causes:
Idiopathic decr. GHRH secretion
hypothalamic tumors

Pituitary causes:
Pituitary tumors
Trauma 
Surgical removal 
Irradiation
Idiopathic
Secretion of abnormal GH molecules
135
Q

Tx of GH deficiency in children

A

MC preprations subcutaneous administration Somatropin

136
Q

Growth hormone therapy should continue until…

A

growth ceases

should retest GH deficient children after completion of growth

137
Q

which children rarely recover GH as an adult?

A

children w/multiple pituitary hormone deficiences

Foundations III- Endocrine (5 decks)

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