Download Endocrine Diseases

Endocrine Diseases
Pituitary Gland
University of New England
Physician Assistant Program
J.B. Handler, M.D.
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Abbreviations
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ACTHadrenocorticotropic
hormone
TSH- thyroid stimulating
hormone
LH- leutinizing hormone
FSH- follicle stimulating
hormone
hCG-human chorionic
gonodatropin
ADH- antidiuretic
hormone
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GH- growth hormone
CO- cardiac output
DI- diabetes insipidus
IGF- insulin growth factor
OCP- oral contraceptive pill
LFT- liver function test
AVP- arginine vasopressin
DJD- degenerative joint disease
SSRI- selective serotonin reuptake inhibitor
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Pituitary Hormones
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Anterior Pituitary: Growth Hormone, Prolactin,
ACTH, TSH, LH, FSH.
Posterior Pituitary: Arginine Vasopressin (ADH,
AVP), Oxytocin.
Hypothalamus: Release of regulatory hormones,
most of which stimulate release of pituitary
hormones. Exception: Prolactin-release is
inhibited by dopamine.
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Hypopituitarism
Hormone deficiencies may be single or
multiple.
 Etiologies: Genetic defects, tumors
(pituitary adenoma), autoimmune, trauma,
irradiation, stroke/intracerebral hemorrhage,
peri-partum (Sheehan’s syndrome- pituitary
infarction following post partum shock or
hemorrhage)
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Hypopituitarism
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LH/FSH- Sex Hormones- If congenital:
hypogonadism- delayed adolescence. If acquired
as an adult: loss of secondary sex characteristics
(beard, axillary and pubic hair, etc) libido,
amenorrhea, infertility; low testosterone/estrogen.
TSH- Thyroid Hormone- Hypothyroidism:
weakness, cold intolerance, constipation, skin/hair
changes, hyperlipidemia, wt. gain.
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ACTH- Cortisol-Adrenal insufficiency:
Weakness, fatigue, weight loss, hypotension.
Growth Hormone-In adults: obesity, asthenia,
decreased CO. In children-serious growth
disturbance.
Panhypopituitarism-lack all of the anterior
pituitary hormones.
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Lab, Diagnostics and Treatment
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Possibilities: ACTHCortisol  hyponatremia,
hypoglycemia; TSH  free T4; LH, FSH
Testosterone, Estradiol.
MRI- Visualization of Pituitary neoplasms and
other CNS pathology.
Transphenoidal pituitary surgery (if tumor)
followed by endocrine replacement therapy: LThyroxin, Testosterone or Estrogen, Cortisol,
hGH.
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Diabetes Insipidus
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Central: Deficiency of AVP/ADH
Primary: Pituitary intact; familial forms (rare).
Secondary: Damage to pituitary or pituitary
stalk by tumor, surgery, anoxia.
Nephrogenic: Inability of the kidneys to respond
to ADH; congenital (lack ADH receptors) and
acquired forms (pyelonephritis, post-obstructive,
tubular interstitial disease, drug induced
(demeclocycline, lithium), hypercalcemia, etc.).
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Signs, Symptoms & Diagnostics
Intense thirst, polyuria (2-20 L/d).
 Lab: Serum- hypernatremia; urine- low
specific gravity.
 Other pituitary deficiencies may be present.
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Diagnostics
Vasospressin challenge: Desmopressin
administered SC or intranasal results in
dramatic decrease in urine volume in central
DI; no response with nephrogenic DI.
 Differential Dx of polyuria/polydipsea: DI,
Diabetes Mellitus, psychogenic polydypsia.
 Complications: Severe dehydration,
hypernatremia.
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Treatment
Central DI: Partial deficiency may require
no treatment other than fluids. Complete
deficiency: Desmopressin (SC, IM, oral,
intranasal); lowest effective dose to avoid
hyponatremia.
 Nephrogenic DI: May respond to
Indomethacin which increases renal
sensitivity to AVP by blocking the action of
prostaglandin E.
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Acromegaly and Gigantism
Excessive GH release, almost always from a
pituitary adenoma.
 GH effects mediated by increased
production of IGF-I in liver.
 These tumors often produce prolactin in
addition to GH additional Sx (see
below).
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Signs and Symptoms
Dependent on when the tumor develops.
 If before closure of epiphyses: Gigantism
 After epiphyseal closure: Acromegaly.
Characterized by enlargement of the hands,
jaw, feet; coarse facial features; bones of
the skull enlarge; deep voice.
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Pituitary Gigantism/Acromegaly
Images.google.com
Acromegaly
“She has Man Hands”:
J. Seinfeld, late 1990’s
Images.google.com
Signs and Symptoms
Associated findings: Hypertension,
cardiomegaly (dilated cardiomyopathy),
insulin resistance/diabetes, DJD. If
untreated, progressive cardiovascular
morbidity and premature death.
 Hypogonadism reflects co-secretion of
prolactin (see below) or pituitary
compression with decreased LH/FSH.
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Lab and Diagnostic Findings
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Bloodwork (Following an overnight fast): serum
IGF-I (5x nl with Acromegaly), prolactin,
glucose; all may be elevated. TSH/Thyroxin if
low, suggests additional pituitary pathology.
Glucose challenge post fast- Elevated GH levels
help confirm the diagnosis (should normally be <
1ng/mL).
MRI- Usually identifies a pituitary adenoma.
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Pituitary Tumor
Images.google.com
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Treatment of Acromegaly
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Transphenoidal microsurgery, which may result
in transient or permanent hypopituitarism.
Octreotide-a somatostatin (somatotropin releaseinhibiting factor) analog. Suppresses GH
secretion; used in patients who continue to have
excessive GH release post-op; very expensive;
injectedshrinks some tumors
– Dopaminergic agents (cabergoline, oral) useful
especially if tumor co-secretes prolactin shrinks
some tumors.
– Pegvisomant- GH receptor antagonist, new.
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Hyperprolactinemia
Prolactin induces lactation during
pregnancy (along with estrogen and
progesterone).
 Control of prolactin production is
inhibitory, mediated by dopamine.
 Etiologies: Pituitary microadenoma (may
also produce GH), drugs (SSRI’s, thiazides,
Cimetidine, Tricyclics, OCP, others);
hypothyroidism, renal failure and cirrhosis.
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Signs and Symptoms
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High prolactin levels suppress GnRHLH/FSH,
resulting in hypogonatropic hypogonadism.
Females: Pre-menopausal woman develop
galactorrhea, oligo/amenorrhea and infertility,
decreased libido, vaginal dryness.
Males: Decreased libido, erectile dysfunction,
gynecomastia, but no galactorrhea.
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Lab and Diagnostic Findings
Baseline labs should include hCG, TSH,
Free Thyroxine, Creatinine and BUN,
LFT’s and Prolactin levels.
 In the absence of pregnancy and renal
failure, a Prolactin level >250ng/mL is
highly suspicious/diagnostic of
Prolactinoma.
 Imaging- MRI
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Treatment
DC offending drug if present.
 Correct other possible etiologies.
 Microprolactinomas grow very slowly and
patients with mild symptoms can be
followed without intervention.
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Treatment
With symptoms of hypogonadism/infertility
or larger tumors: Dopamine agonists
(Cabergoline, Bromocriptine) can
successfully treat symptoms, correct
amenorrhea and galactorrhea, and shrink the
tumor.
 Transphenoidal pituitary surgery reserved
for individuals with large macroadenomas
that abut/compress the optic chiasm.
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