Post on 06-May-2015
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Pituitary Gland Pituitary Gland DiseasesDiseases
SMS 3023Dr. Mohanad R. Alwan
Endocrine Glands
• Controls many body functions– exerts control by releasing special chemical substances
into the blood called Hormones– Hormones affect other endocrine glands or body
systems
• Ductless glands
• Secrete hormones directly into bloodstream– Hormones are quickly distributed by bloodstream
throughout the body
Hormones• Chemicals produced by endocrine glands.
• Act on target organs elsewhere in body.
• Control/coordinate widespread processes:• Homeostasis.
• Reproduction.
• Growth & Development.
• Metabolism.
• Response to stress.• Overlaps with the Sympathetic Nervous System
Hormones
Hormones are classified as:ProteinsPolypeptides (amino acid derivatives)Lipids (fatty acid derivatives or steroids)
Hormones
Amount of hormone reaching target tissue directly correlates with concentration of hormone in blood.
Constant level hormones• Thyroid hormones
Variable level hormones• Epinephrine (adrenaline) release
Cyclic level hormones• Reproductive hormones
The Endocrine System Consists of several glands located in various parts of
the body Specific Glands
Hypothalamus Pituitary Thyroid Parathyroid Adrenal Kidneys Pancreatic Islets Ovaries Testes
Hypothalamus Produces several releasing and inhibiting factors
that stimulate or inhibit anterior pituitary’s secretion of hormones.
Produces hormones that are stored in and released from posterior pituitary.
Hypothalamus Also responsible for:
Regulation of water balanceEsophageal swallowingBody temperature regulation (shivering)Food/water intake (appetite)Sleep-wake cycleAutonomic functions
HypothalamicHypothalamic
Hypothalamic neural cells synthesize specific releasing and inhibiting hormones that are secreted directly into the portal vessels of the pituitary stalk.
Hypothalamic-pituitary portal plexus provides the major blood source for the anterior pituitary.
Hypothalamic releasing hormonesHypothalamic releasing hormones
Hypothalamic releasing hormone Effect on pituitary
Corticotropin releasing hormone (CRH)
Stimulates ACTH secretion
Thyrotropin releasing hormone (TRH)
Stimulates TSH and Prolactin secretion
Growth hormone releasing hormone (GHRH)
Stimulates GH secretion
Somatostatin Inhibits GH (and other hormone) secretion
Gonadotropin releasing hormone (GnRH) a.k.a LHRH
Stimulates LH and FSH secretion
Prolactin releasing hormone (PRH) Stimulates PRL secretion
Prolactin inhibiting hormone (dopamine)
Inhibits PRL secretion
Hypothalamic -Pituitary communicationHypothalamic -Pituitary communication
Pituitary Gland
Small gland located on stalk hanging from base of brain.
“The Master Gland” Primary function is to control other glands.Produces many hormones.Secretion is controlled by hypothalamus in base of brain.
Pituitary Gland• Weight 600 mg• Is located within the bony cavity (sella turcica)• Anatomically and functionally distinct anterior
and posterior lobes• Anterior Pituitary-adenohypophysis • Posterior pituitary-neurohypophysis
Histology of the PG
Anterior pituitary cells were originally classified as
• Acidophils cells• Basophils cells• Chromophope cells
Histology of PG Now with immunocytochemical and electron
microscopic techniques,classified cells by their secretary products
• Somatotrophs cells • a. GH secreting cells • Account about 50% of anterior P.G • Acidophilic stained
Histology of PG
• Lactotrophic • a. Prl secreting cells • b. acidophilic stained • c. 10-15% of anterior PG• Thyrotrophis • a. TSH secreting cells • b. basophilic cells • c. < 10% of anterior PG
Histology of PG
• Corticotrophs a. ACTH secretary cells b. basophilic cells c. 15-20% of anterior PG
• Gonadotrophs a. LH,FSH secretary cells b. basophilic staining c. 10-15% of anterior PG
Pituitary Development
• The pituitary originate from different source. • The anterior pituitary from Rathke´s pouch
(which is an embryonic invagination of the pharyngeal
epithelium).• The posterior pituitary from an outgrow of the
hypothalamus.
• Adrenocorticotropic hormone(ACTH)• Thyroid-stimulating hormone(TSH)• Growth hormone, Prolactin • Luteinizing hormone, • Follicle stimulating hormone• melanocyte–stimulating hormones
o Oxytocin,o Antidiuretic hormone
Pituitary Gland Two areas
Anterior PituitaryPosterior Pituitary
Structurally, functionally different
Pituitary Gland
Anterior Pituitary HormonesThyroid-Stimulating Hormone (TSH)
stimulates release of hormones from Thyroid thyroxine (T4) and triiodothyronine (T3): stimulate
metabolism of all cellscalcitonin: lowers the amount of calcium in the blood by
inhibiting breakdown of bone
released when stimulated by TSH abnormal conditions
hyperthyroidism: too much TSH releasehypothyroidism: too little TSH release
Pituitary Gland
Anterior PituitaryGrowth Hormone (GH)
stimulates growth of all organs and increases blood glucose concentration
decreases glucose usage increases consumption of fats as an energy source
Adreno-Corticotrophic Hormone (ACTH)stimulates the release of adrenal cortex hormones
Pituitary Gland
Anterior PituitaryFollicle Stimulating Hormone (FSH)
females - stimulates maturation of ova; release of estrogen
males - stimulates testes to grow; produce spermLuteinizing Hormone (LH)
females - stimulates ovulation; growth of corpus luteum
males - stimulates testes to secrete testosterone
Pituitary Gland
Anterior PituitaryProlactin
stimulates breast development during pregnancy; milk production after delivery
Melanocyte Stimulating Hormone (MSH)stimulates synthesis, dispersion of melanin pigment
in skin
Pituitary GlandPituitary Gland
Posterior PituitaryStores, releases two hormones produced in
hypothalamusAntidiuretic hormone (ADH)Oxytocin
Pituitary Gland
Posterior Pituitary Hormones: Antidiuretic hormone (ADH)
Stimulates water retention by kidneys reabsorb sodium and water
Abnormal conditionsUndersecretion: diabetes insipidus (“water diabetes”)Oversecretion: Syndrome of Inappropriate Antidiuretic
Hormone (SIADH)
OxytocinStimulates contraction of uterus at end of pregnancy
(Pitocin®); release of milk from breast
Pineal Gland Located within the Diencephalon Melatonin
Inhibits ovarian hormonesMay regulate the body’s internal clock
Anterior PituitaryAnterior Pituitary
Is often referred to as the “MASTER GLAND” because, it orchestrates the complex regulatory functions of multiple other endocrine glands.
Anterior Pituitary Anterior Pituitary InsufficiencyInsufficiency
EtiologyEtiology
Reduced pituitary function can result from inhereited disorders; more commonly,
it is acquired and reflects the mass effects of tumors or the consequences of inflamation or vascular damage.
Causes of hypopituitarismCauses of hypopituitarism
Tumours (tu’) Pituitary tumor Adenoma,craniopharyngioma Cerebral tumor
Hypothalamic disorders Tumor Functional disturbance-Eg -Anorexia nervosa Isolated GH and GnH
secretion due to impaired secretion of hypothalamic releasing hormones
Miscellaneous Sarcoidosis (inflammation of L.N) Histocytosis X (abnormal increase
in the number of immune cells ) Haemochromatosis
Vascular ds Necrosis (Sheehan’s synd) Infarction Severe hypotension Cranial arteritisTrauma
Infection Meningitis esp TB, syphilis
Iatrogenic Surgery Irradiation Prolonged rx with glucocorticoid
or thyroid hormones-isolated ACTH or TSH suppression
Developmental and Genetic Causes of Developmental and Genetic Causes of HypopituitarismHypopituitarism
Pituitary DisplasiaTissue-Specific Factor MutationsDevelopmental Hypotalamic Dysfunction:
Kallmann Syndrome (Hypogonadotropic hypogonadism)
Laurence-Moon-Bardet-Biedl Syndrome (involves many body systems)
Fröhlich Syndrome (childhood metabolicdisorder)
Prader-Willi Syndrome.
Acquired HypopituitarismAcquired Hypopituitarism
Trauma. Vascular Pituitary or hypothalamic neoplasms Inflammatory diseases. Infiltrative disorders such as sarcoidosis,
hemochromatosis.
ANTERIOR PITUITARY HYPOFUNCTION ANTERIOR PITUITARY HYPOFUNCTION (hypopituitarism)(hypopituitarism)
3 most common causes:3 most common causes: Non secretory adenoma of ant pituitaryNon secretory adenoma of ant pituitary Sheehan’s syndrome Sheehan’s syndrome ((postpartum pituitary
necrosis) Empty sella syndrome Empty sella syndrome ((pituitary gland become
shrinks or becomes flattened)
Partial hypopituitarism is more frequent than complete Partial hypopituitarism is more frequent than complete loss of pit functionsloss of pit functions
Sx/signs do not manifest until > 75% of ant lobe is Sx/signs do not manifest until > 75% of ant lobe is destroyeddestroyed
GH secretion is an early feature of pit failure-effects > GH secretion is an early feature of pit failure-effects > dramatic in children but less significant in adultsdramatic in children but less significant in adults
LH/ FSH are affected before ACTHLH/ FSH are affected before ACTH Hypothyroidism is an uncommon presenting feature of Hypothyroidism is an uncommon presenting feature of
pit failurepit failure
Clinical featuresClinical features
Hormone Features of deficiency
GH Children: growth retardationAdults: ↓muscle bulkTendency to hypoglycaemia.
Prolactin Failure of lactation
Gonadotrophins Children: delayed pubertyFemale: oligomenorrhoea, infertility,atrophy of breast & genitaliaMale:Impotence,azoospermia,testicular atrophyBoth sexes: LO libido,LO body hair
ACTH Weight loss, hypotension, hypoglycaemia, decrease skin pigmentation
TSH Weight gain, cold intolerence,fatique
Vasopressin Thirst, polyuria
Posterior Pituitary Posterior Pituitary hypofunctionhypofunction
CausesCauses ADH production ADH production cranial diabetes cranial diabetes
insipidus insipidus (DI)(DI)
Causes of cranial DICauses of cranial DI Tumours-craniopharyngioma, secondary tumours Tumours-craniopharyngioma, secondary tumours
(metastatic CA), pituitary tumours with suprasella (metastatic CA), pituitary tumours with suprasella extension.extension.
Granulomatous disease.Granulomatous disease. Meningitis, abscess and encephalitis.Meningitis, abscess and encephalitis. Vascular disorders.Vascular disorders. Trauma.Trauma. Surgery.Surgery. Idiopathic.Idiopathic.
Posterior Pituitary Posterior Pituitary hypofunctionhypofunction
EffectsEffects
Polyuria-uncontrolled renal water Polyuria-uncontrolled renal water excretion, tendency to dehydrationexcretion, tendency to dehydration
Polydipsia-excessive thirst, dehydration Polydipsia-excessive thirst, dehydration stimulate thirst centre resulting in stimulate thirst centre resulting in increase water intakeincrease water intake
Key featuresKey features
Hypotension Decreased pulse pressure Tachycardia Increased Hbg,hct and BUN Increased UOP Poor skin turgor Irritablilty Decreased coginition Hyperthermia Lethargy leading to coma
PITUITARY HYPERFUNCTIONPITUITARY HYPERFUNCTION(HYPERPITUITARISM)(HYPERPITUITARISM)
CausesCauses
Pituitary adenoma Pituitary adenoma Carcinoma (rare)Carcinoma (rare) Hypothalamic disorder-excess stimulation of the Hypothalamic disorder-excess stimulation of the
pituitary (rare)pituitary (rare)
Order of frequency with which hormone secretion Order of frequency with which hormone secretion occurs in pituitary tumour is prolactin (relatively occurs in pituitary tumour is prolactin (relatively common) common) GH GH ACTH ACTH gonadotrophin gonadotrophin TSH TSH
HyperpituitarismHyperpituitarism - - excessive production of adenohypophexcessive production of adenohypophyyssealeal hormones
PITUITARY HYPERFUNCTIONPITUITARY HYPERFUNCTION(HYPERPITUITARISM)(HYPERPITUITARISM)
Prolactin excess Hyperprolactinaemia
GH excess Acromegaly/ gigantism
ACTH excess Cushing’s disease
TSH excess (rare) Secondary hyperthyroidism
Gonadotrophin excess
menstrual disorders and infertillity
Consequences:Consequences:
a)a) Excessive Secretion ofExcessive Secretion of prolactinprolactin secretion secretion of GnRH of GnRH gonadotrophinsgonadotrophins
In men: impotency, decreased libidoIn men: impotency, decreased libido
In women: amenorrhea, galactorrheaIn women: amenorrhea, galactorrhea
b) Excessive Secretion ofb) Excessive Secretion of somatotrophinesomatotrophine (growth (growth hormonehormone))
acromegaly (in adults)acromegaly (in adults)
gigantism (in adolescents whose epiphysealgigantism (in adolescents whose epiphyseal
plates have not yet closed)plates have not yet closed)
b)-continuing b)-continuing PathomechanismsPathomechanisms involved involved::-The usual GH baseline secretion pattern is lost (as are sleep –The usual GH baseline secretion pattern is lost (as are sleep – related GHrelated GH peaks)peaks)
- GH secretion is slightly elevated GH secretion is slightly elevated somatomedin somatomedin stimulation of growth stimulation of growth (in adolescent)(in adolescent)
- - CConnective tissue onnective tissue proliferationproliferation
- - BBony proliferation ony proliferation characteristic appearance of acromegaly characteristic appearance of acromegaly
- - PPhosphate reabsorbtion in renal tubules hosphate reabsorbtion in renal tubules hyperphosphatemia hyperphosphatemia
- - IImpairement of carbohydrate tolerancempairement of carbohydrate tolerance
- - M Metabolic rateetabolic rate
- HHyperglycemia - yperglycemia - it is a result of GH inhibition of peripheral glucose uptake it is a result of GH inhibition of peripheral glucose uptake
and increase hepatic glucose production and increase hepatic glucose production compensatory hyperinsulinism compensatory hyperinsulinism insulin resistance insulin resistance diabetes mellitus diabetes mellitus
C. C. In adultIn adultss::
D. D. Excessive Secretion of corticotrophinExcessive Secretion of corticotrophin ( (ACTH) ACTH) central form of central form of
Cushing syndrome (Cushing disease)Cushing syndrome (Cushing disease)
Causes:Causes: micro- or macroadenomas of adenohypophmicro- or macroadenomas of adenohypophyysis, hypothalamic sis, hypothalamic
disordersdisorders
Pathophysiology:Pathophysiology:CChronic hypercortisolismhronic hypercortisolism is the main disturbance is the main disturbance of of ACTH ACTH
Symptoms and signs:Symptoms and signs: weight gain:weight gain: - - accumulation of adipose tissue in the trunk, facial, and accumulation of adipose tissue in the trunk, facial, and cervical areas (truncal obesity, moon face, buffalo hump) cervical areas (truncal obesity, moon face, buffalo hump)
- - weight gain from Na and water retentionweight gain from Na and water retention
glucose intoleranceglucose intolerance DM type 2 DM type 2
polyuria:polyuria: osmotic polyuria due to glycosuria osmotic polyuria due to glycosuria
E. E. Protein WastingProtein Wasting: : due to catabolic effects of cortisol on peripheral tissue due to catabolic effects of cortisol on peripheral tissue
(muscle wasting (muscle wasting muscle atrophy and weakness muscle atrophy and weakness thin lower thin lower
extremitiesextremities))
in bone:in bone: - loss of protein matrix - loss of protein matrix osteoporosis osteoporosis - - blood calcium concentration blood calcium concentration renal stones renal stones
in skin:in skin: - loss of collagen loss of collagen thin, weakened integumentary thin, weakened integumentary tissues tissues purple striae; rupture of small vesels purple striae; rupture of small vesels
- thin, atrophic skin is easily damaged, leading to skin breaks thin, atrophic skin is easily damaged, leading to skin breaks and ulcerationand ulceration
F. F. Hyperpigmentation:Hyperpigmentation: due to very high levels of ACTHdue to very high levels of ACTH - - manifestation in: manifestation in: mucous membranes,mucous membranes, hair, andhair, and skinskin
Hypertension:Hypertension: results from permissive effect of cortisol on the actions of results from permissive effect of cortisol on the actions of
the catecholamines (KA) the catecholamines (KA) vascular sensitivity to KA vascular sensitivity to KA vasoconstriction vasoconstriction hypertension hypertension
Suppression of the immune systemSuppression of the immune system susceptibility to infections susceptibility to infections
alteration of mental statusalteration of mental status - - from irritability and depression from irritability and depression up to schizophreniaup to schizophrenia
symptoms and signs of symptoms and signs of adrenal androgenadrenal androgenss level level in women:in women:
- - hair growth (especially facial hair) hair growth (especially facial hair)- acne- acne- oligoamenorrhea- oligoamenorrhea
- changes of the vois- changes of the vois
Hyperglycemia, glycosuria, hypokalemia, metabolic alkalosis Hyperglycemia, glycosuria, hypokalemia, metabolic alkalosis
Excessive Secretion Of Thyreotrophin and GonadotrophinsExcessive Secretion Of Thyreotrophin and Gonadotrophins is is rarerare
Measurement of anterior pituitary Measurement of anterior pituitary hormoneshormones
Measured in serum by immunoassay Dynamic tests/ functional tests are important
tools in pituitary functions and other endocrine organs.
Basic principle of dynamic tests: Hypofunction - stimulation tests Hyperfunction-suppression tests
Magnetic resonance imaging (MRI)
TreatmentTreatment
Hormone replacement therapy, including glucocorticoids, thyroid hormone, sex steroids, growth hormone and vasopressin, is usually free of complications.
Glucocorticoid replacement require careful dose adjustments during stressful events.
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