Pituitary glandAnatomyHistologyPhysiologyDiseases of pituitary gland

Anatomy of pituitary glandPituitary gland lies in the base of the skull in a portion of sphenoid bone called s.tIt consist of tow lobe anterior lobe (adenohypophysis),and posterior lobe (neurohypophysis)The size of the gland which the anterior lobe consist 2/3 varies considerably It measures 15X10X6 mml wt 500-900 mgIt may double in size during pregnancy

Sella turcica of the sphlenoid boneLocation of the Pituitary

Blood supplyMost richly vascularized of all mammalian tissues,receiving 0.8 ml/min from portal circulation.It supply by middle inferior and superior hypophysial arteries from the internal carotid arteries

The Hypothalamic-Hypophyseal Portal System2 capillary beds directly joined by blood vessels

Histology of the PG 1 Anterior pituitary cells were originally classified asAcidophils cellsBasophils cellsChromophope cells

Histology of PG 2 Now with immunocytochemical and electron microscopic techniques,classified cells by their secretary productsSomatotrophs cells a. GH secreting cells b. Account about 50% of anterior P.G c. Acidophilic stained

Histology of PG 3Lactotrophic a. Prl secreting cells b. acidophilic stained c. 10-15% of anterior PGThyrotrophis a. TSH secreting cells b. basophilic cells c. < 10% of anterior PG

Histology of PG 4Corticotrophs a. ACTH secretary cells b. basophilic cells c. 15-20% of anterior PGGonadotrophs a. LH,FSH secretary cells b. basophilic staining c. 10-15% of anterior PG

Anterior pituitary hormoneGHPRLTSHACTHLHFSH

Posterior pituitary hormoneVASOPRESSIN

OXYTOCIN

hypopituitarismHypopituitrism is manifested by diminished or absent secretion of one or more PHThe development of sign and symptom is often slow and insidiousHypo pit is either primary event caused by destruction of APG or 2ndary resulting from deficiency of hypothalamic SFTreatment and prognosis depend on the extent of hypofunction,the underlying cause and the location of the lesion

HypopituitarismIs usually gradual and may have single hormone deficiency or multiple hormoneGH deficiency a. deficiency in children lead to short stature b. deficiency in adult lead to vague non specific symptoms,fatigue decrease muscle mass,loss of libido

Gonadotrophin H.D (hypogonadism) In women a. before puberty primary amenorrhea and failure of puberty development b. after puberty 2ndary amenorrhea and regression of 2ndary sexual characteristic c. infertility

hypogonadismIn men a. before puberty failure of puberty development b. after puberty decrease libido or impotence loss of 2ndary sexual characteristic infertility

TSH deficiency lead to 2ndary hypothyroidismClinical feature cold intolerance dry skin,loss of hair mental dullness constipation increase in wt bradycardia,slow reflexes hoarseness, puffiness of the face

ACTH deficiency lead to 2ndary adrenocortical insufficiencyClinical feature Weakness Nausea and vomiting Anorexia Wt loss Postural hypotension

Causes of hypopituitarismInfarction postpartum necrosis (Sheehan syndrome) vascular disease head traumaInfections tuberculosis , fungi pyogenic , syphilis toxoplasmosis

Hypopituitarism 2Granulomas Sarcoidosis HistiocytosisAutoimmune lymphocytic hypophysitisNeoplasm's involving pituitary Pituitary adenoma Craniopharyngioma Metastasis or or primary carcinoma (rare)

Hypopituitarism 3Aneurysm of internal carotid artery HemochromatosisIdiopathic or genetic deficient production of pituitary hormone synthesis of abnormal hormoneIatrogenic stalk section radiation hypophysectomy

Hypopituitarism 3Primary hypothalamic disorders tumor (craniopharyngioma) granulomas (histiocytosis x) genetic or idiopathic releasing H.D head trauma structural anomalies of hypothalamus

Diagnosis of PD by PH stimulation test

Pituitary stimulation test 2

Treatment of hypopituitrism

Pituitary tumorsNearly always benign account for 10% of intracranial neoplasm Pituitary microaadenoma is intrasellar adenoma less than 1 cm in diameter Pituitary macroadenoma are those larger than 1 cm in diameter

Type of pituitary tumors

Clinical presentation of pituitary tumoursHormone hypersecretion

Space occupying lesionHeadachesVisual loss (field defect)

Hormone deficiency statesInterference with surrounding normal pituitary

Tumours of the anterior pituitary can cause syndromes of hormone excessGH

ACTH

TSH

LH/FSH

PRLAcromegaly

Cushings disease

Secondary thyrotoxicosis

(Non-functioning pituitary tumour)

Prolactinoma

Treatment of P.TSurgical Transfrontal or transsphenoidalRadiological Conventional irradiation,heavy particle IMedical Dopamine agonist (bromocriptin) Somastatin analog (octreotide)