1. pars nervosa (post pit) connected to hypothal via pituitary stalk → post pit is a storage area for hypothal hormones 2. pars intermedia 3. pars tuberalis 4. pars distalis (ant pit)

most common to least common 1. prolactinoma PRIMARY TX: medical tx with dopamine agonist! (decreases prolactin and shrinks tumor) 2. gonadotroph/non-secr adenoma 3. GH-secreting adenoma → acromegaly 4. ACTH-secreting adenoma → Cushing's disease 5. TSH-secreting adenoma 2-5: primary tx is SURGERY, radiation, then med tx

_excess hormone secretion from ant pituitary cells_ GH → gigantism, acromegaly LH/FSH → precocious puberty, central hypergonadism ACTH → Cushing's disease TSH → central hyperthyroidism or... _release of tonic dopamine inhibition (PRL)_ PRL → hyperprolactinemia → decr gonadotropins

result of anatomic lesions affecting anterior pit GH → pit dwarfism, adult GH def LH/FSH → secondary hypogonadism ACTH → secondary adrenal insuff TSH → secondary hypothyroidism PRL → failure to lactate

deficiency of something along the axis: GHRH from hypothal GH form pituitary IGF1 from liver clinical signs/sx _children_: short stature, frontal bossing, central obesity, high pitched voice _adult_: decr bone density, abnl lipid profile, dep/decr well being, central obesity etiology NEUROENDOCRINE congenital/inherited septo-optic dysplasia acquired anatomic lesions (pituitary, hypothal, craniopharyngioma) fx/idiopathic (starvation, child abuse, failure to thrive)

2/10 Hypothal Pit Disorders - Meininger Flashcards by Tom Kuriakose

ANATOMY

hypothal and pituitary

both sit at base of brain

pituitary aka “master gland” → control many other endocrine organs (thyroid, adrenals, testes/ovaries)

sits in sella turcica (‘Turkish saddle’) → surrounded by bone on all sides except superiorly

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pituitary parts

pars nervosa (post pit)
- connected to hypothal via pituitary stalk → post pit is a storage area for hypothal hormones
pars intermedia
pars tuberalis
pars distalis (ant pit)

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pituitary adenomas

most common to least common

prolactinoma
- PRIMARY TX: medical tx with dopamine agonist! (decreases prolactin and shrinks tumor)
gonadotroph/non-secr adenoma
GH-secreting adenoma → acromegaly
ACTH-secreting adenoma → Cushing’s disease
TSH-secreting adenoma

2-5: primary tx is SURGERY, radiation, then med tx

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consequences of pituitary tumors

hypopituitarism → not enough space for actual fxal cells to grow into and operate in
optic nerve/chiasm compression → visual field abnormalities
pituitary stalk compression → central DI
CSF leak / meningitis
cavernous sinus invasion → CN palsy

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visual field issues

optic nerve compression
optic chiasm compression
optic tract compression

optic nerve comp

optic chiasm comp: bitemporal hemianopsia

optic tract comp

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pituitary fx abnormalities

hypersecretion & hyposecretion

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hormone terminology

“levels”
organs
produce…

tertiary/central: hypothalamus → RELEASING HORMONES
- TRH, GnRH, CRH
secondary/central: pituitary → TROPHIC HORMONES
primary/end-organ: endocrine organ →

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anterior pituitary hormones

somatotrophs
- growth hormone (GH)
gonadotrophs
- follicle stim hormone (FSH)
- luteinizing hormone (LH)
corticotrophs
- adrenocorticotrophic hormone (ACTH)
thyrotrophs
- thyroid stim hormone (TSH)
lactotrophs
- prolactin (PRL)

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posterior pituitary hormones

antidiuretic hormone (ADH) aka vasopressin
- lesions affecting these neurons → central DI
oxytocin

*both made in hypothalamus, stored and released from post pit

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hypersecretion

excess hormone secretion from ant pituitary cells

GH → gigantism, acromegaly
LH/FSH → precocious puberty, central hypergonadism
ACTH → Cushing’s disease
TSH → central hyperthyroidism

or…

release of tonic dopamine inhibition (PRL)

PRL → hyperprolactinemia → decr gonadotropins

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hyposecretion

result of anatomic lesions affecting anterior pit

GH → pit dwarfism, adult GH def
LH/FSH → secondary hypogonadism
ACTH → secondary adrenal insuff
TSH → secondary hypothyroidism
PRL → failure to lactate

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acromegaly

what is it

signs/sx

normal axis

GH excess

enlargement at periphery → hands, feet

GH axis: normal

interplay of GHRH and somatostatin
- hypothal releases GHRH → stim GH release
- hypothal releases somatostain → inhib GH release
GH stimulates liver to release IGF1

negative feedback:

GH on hypothal and pituitary
IGF1 on hypothal and pituitary

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endocrine testing principle

hypo and hyper secretion

to rule out hyposecretion…

stimulate that endocrine axis

to rule out hypersecretion…

suppress that endocrine axis (ex. dexamethasone suppression test → neg feedback on pituitary to decr ACTH secretion)

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acromegaly

dx/tx

dx:

elevated IGF1
GH NOT suppressed 1hr post oral glucose tolerance test

tx:

surgical
rad
pharma
- octreotice (somatostain analog)
- pegvisomant (GH receptor antagonist)

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GH deficiency

deficiency of something along the axis:

GHRH from hypothal
GH form pituitary
IGF1 from liver

clinical signs/sx

children: short stature, frontal bossing, central obesity, high pitched voice
adult: decr bone density, abnl lipid profile, dep/decr well being, central obesity

etiology

NEUROENDOCRINE
- congenital/inherited
  - septo-optic dysplasia
- acquired
  - anatomic lesions (pituitary, hypothal, craniopharyngioma)
  - fx/idiopathic (starvation, child abuse, failure to thrive)

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GH deficiency

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stimulation test
- insulin tolerance test
- arginine
- GHRH
- exercise

pharmacological
- GH
- GHRH

hypothal-pit-gonadal axis

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GNRH from hypothal is released in PULSATILE fashion

LH from pituitary is released in PULSATILE fashion
- testosterone production from Leydig cells
- ovarian steroidogenesis
FSH is non-pulsatile
- spermatogenesis
- growth of ovarian follicular granulosa cell

abnormalities of HPG axis

4 categories

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congenital/inherited
- Kallman’s syndrome (isolated gonadotropin def w anosmia or hypoosmia)
acquired
- anatomic lesions (hypothal, pit)
functional/idiopathic
- starvation/low body weight
- delayed puberty
- precocious puberty
ectopic
- ectopic hCG, nonseminoma gernm cell tumors, lung carcinomas, hepatomas

HPG axis abnormalities

clinical manifestations

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hypogonadism
- amenorrhea
- gynecomastia
- infertility
- decr libido
- absence or decr in secondary sexual chars
- osteoporosis
hypergonadism
- premature secondary sex chars

HPG axis abnormalities

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congenital/inherited

Kallman’s syndrome
- pulsatile GnRH
- use of hCG and hMGs (FSH)

acquired

pit surgery

fxal/idiopathic

incr body weight (anorexia nervosa, rigorous exercise)
precocious puberty (long acting GnRH agonists)

miscellaneous (might not hit all aspects of disease…ex. fertility)

estrogen/progesterone replacement
testosterone replacement

Cushing’s disease

what axis?

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HPA

hypothal-pit-adrenal axis

hypothalamus-pituitary-adrenal axis

normal

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hypothal releases CRH
pituitary releases corticotropin
adrenals release cortisol

negative feedback

cortisol exercises negative feedback on hypothal and pituitary

Cushing’s SYNDROME

(and where Cushing’s disease falls within that)

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excess cortisol in body

causes can be…

ACTH-dependent
- Cushing’s disease: incr in pit ACTH
- ectopic ACTH
ACTH-indep
- adrenal adenoma or carcinoma
- iatrogenic (MOST COMMON)

clinical manifestations of Cushing’s Disease

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Cushing's Disease dx/tx

_dx_ * 1mg overnight dexamethasone suppression test * 24h urine free cortisol _tx_ * surgical * pituitary * adrenal (rare) → can result in Nelson's Syndrome * radiation * pharmacological * ketoconazole, metyrapone, aminoglutethimide → inhibit adrenal steroid enzymes

secondary adrenocortical insufficiency causes

most common type of adrenal insuff (often iatrogenic) 1. acquired * anatomic lesions (pituitary, hypothal) 2. pharma * withdrawal of prescribed glucocorticoids * withdrawal of medications with glucocorticoid-like effect (ex. megesterol)

2 adrenal insuff clinical manifestations

* n/v * fatigue/weakness * lightheadedness/confusion * hypotension * fever * hypoglycemia * hypoNa (bc glucocorticoid def, NOT mineralocorticoid def) * NOT hyperpig

2 adrenal insuff dx/tx

_dx_ * stimulation tests * ACTH (cortrosyn) stim test * insulin tolerance test * adrenal insufficiency with decr ACTH _tx_ * pharma * clucocorticoid replacement

HTP axis normal

hypothalamus-pituitary-thyroid axis 1. _hypothalamus_ releases **TRH** (+), **somatostatin** (-) 2. _pituitary_ releases **thyrotropin** 3. _thyroid_ releases **T3** and **T4** negative feedback: * T3 and T4 exert neg feedback on hypothal and pit

neuroendo causes of thyroid disease secondary hyper/hypothyroidism

note both involve TSH/T4/T3 going in SAME DIRECTION _secondary hyperthyroidism_ * RAREST secretory pit tumor * incr TSH, T4, T3 * tx: pit surgery/rad/pharma _secondary hypothyroidism_ * usually pit lesion * decr TSH, T4, T3 * labs similar to sick euthyroid symdrome * tx depends on cause...pit surg and thyroid hormone replacement * \*\*\*before relacing thyroid, want to make sure pt doesnt have BOTH thyroid def and adrenal insufficiency! * thyroid hormone controls metabolism BUT in context of person with adrenal insuff...if you restore thyroid hormone, the remaining cortisol is goign to be metabolized faster! could make adrenal insuff worse! → adrenal crisis

prolactin axis

prolactin is not stimulated - it is CONSTITUTIVELY INHIBITED via DA secretion from hypothal sooo, block DA → prolactin released

causes of hyperprolactinemia

* microprolactinoma (\<200) * macroprolactinoma (\>200) * pit stalk compression * meds which interfere with DA pathways (antipsychs) * primary hypothyroidism * TRH → TSH and prolactin secretion * pregnancy

hyperprolactinemia clinical manifestations tx

elevated PRL → inhibited GnRH release → decr gonadotropins * similar clinical manifestations as hypogonadism * **galactorrhea** * oligomenorrhea/amenorrhea * infertility * gynecomastia * osteoporosis _tx_ * PRL-secreting adenomas → first line tx = PHARMA * bromocriptine (short acting DA agonist) * cabergoline (long acting DA agonist)

PRL deficiency

inability to lactate consider/evaluate... * panhypopituitarism * eval other pit axes

2/10 Hypothal Pit Disorders - Meininger Flashcards

(34 cards)