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Lect 1-pituitary insufficiency
The pituitary gland is a small gland located at the base of the brain that regulates several important bodily functions. It produces hormones that control other endocrine glands like the thyroid, adrenals, and ovaries/testes. The pituitary can be affected by tumors, trauma, infections, or genetic conditions which can cause it to produce too much or too little of its hormones. This can lead to symptoms like abnormal growth, changes in menstrual cycles, low libido, and weight gain or loss depending on which hormones are affected. Treatment involves hormone replacement therapy to address deficiencies.
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Lect 1-pituitary insufficiency
- 1. Pituitary Gland DiseasesSMS ????? Dr. Mohanad R. Alwan
- 2. Pituitary Gland Weight600 mg Is located within the bony cavity (sella turcica) Anatomically and functionally distinct anterior and posterior lobes Anterior Pituitary-adenohypophysis Posterior pituitary-neurohypophysis
- 3. Adrenocorticotropic hormone(ACTH) Thyroid-stimulatinghormone(TSH) Growth hormone, Prolactin Luteinizing hormone, Follicle stimulating hormone melanocyte–stimulating hormones Oxytocin, Antidiuretic hormone
- 4. Pituitary Development Thepituitary 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 .
- 5. Hypothalamic Hypothalamic neuralce l ls 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.
- 6. Hypothalamic releasing hormonesHypothalamic 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
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- 9. Anterior Pituitary Isoften referred to as the “MASTER GLAND” because, it orchestrates the complex regulatory functions of multiple other endocrine glands.
- 10. Produces six majorhormones: Prolactin (PRL) Growth hormone (GH) Adrenoicorticotropin hormone (ACTH) Luteinizing hormone (LH) Follicle-stimulating hormone (FSH) Thyroid-stimulating hormone (TSH)
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- 13. Etiology Reduced pituitaryfunction 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.
- 14. Causes of hypopituitarismTumours (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 arteritis Trauma Infection Meningitis esp TB, syphilis Iatrogenic Surgery Irradiation Prolonged rx with glucocorticoid or thyroid hormones-isolated ACTH or TSH suppression
- 15. Developmental and GeneticCauses of Hypopituitarism Pituitary Displasia Tissue-Specific Factor Mutations Developmental Hypotalamic Dysfunction: Kallmann Syndrome ( Hypogonadotropic hypogonadism) Laurence-Moon-Bardet-Biedl Syndrome ( involves many body systems) Fröhlich Syndrome ( childhood metabolicdisorder) Prader-Willi Syndrome.
- 16. Acquired Hypopituitarism Trauma.Vascular Pituitary or hypothalamic neoplasms Inflammatory diseases. Infiltrative disorders such as sarcoidosis, hemochromatosis.
- 17. ANTERIOR PITUITARY HYPOFUNCTION(hypopituitarism) 3 most common causes: Non secretory adenoma of ant pituitary Sheehan’s syndrome ( postpartum pituitary necrosis) Empty sella syndrome ( pituitary gland become shrinks or becomes flattened)
- 18. Partial hypopituitarism ismore frequent than complete loss of pit functions Sx/signs do not manifest until > 75% of ant lobe is destroyed GH secretion is an early feature of pit failure-effects > dramatic in children but less significant in adults LH/ FSH are affected before ACTH Hypothyroidism is an uncommon presenting feature of pit failure
- 19. Clinical features Hormone Features of deficiency GH Children: growth retardation Adults: ↓muscle bulk Tendency to hypoglycaemia. Prolactin Failure of lactation Gonadotrophins Children: delayed puberty Female: oligomenorrhoea, infertility,atrophy of breast & genitalia Male:Impotence,azoospermia,testicular atrophy Both sexes: LO libido,LO body hair ACTH Weight loss, hypotension, hypoglycaemia, decrease skin pigmentation TSH Weight gain, cold intolerence,fatique Vasopressin Thirst, polyuria
- 20. Posterior Pituitary hypofunctionCauses ADH production cranial diabetes insipidus (DI) Causes of cranial DI Tumours-craniopharyngioma, secondary tumours (metastatic CA), pituitary tumours with suprasella extension. Granulomatous disease. Meningitis, abscess and encephalitis. Vascular disorders. Trauma. Surgery. Idiopathic.
- 21. Posterior Pituitary hypofunctionEffects Polyuria-uncontrolled renal water excretion, tendency to dehydration Polydipsia-excessive thirst, dehydration stimulate thirst centre resulting in increase water intake
- 22. PITUITARY HYPERFUNCTION (HYPERPITUITARISM)Causes Pituitary adenoma Carcinoma (rare) Hypothalamic disorder-excess stimulation of the pituitary (rare) Order of frequency with which hormone secretion occurs in pituitary tumour is prolactin (relatively common) GH ACTH gonadotrophin TSH Hyperpituitarism - excessive production of adenohypoph y s eal hormones
- 23. PITUITARY HYPERFUNCTION (HYPERPITUITARISM)Prolactin excess Hyperprolactinaemia GH excess Acromegaly/ gigantism ACTH excess Cushing’s disease TSH excess (rare) Secondary hyperthyroidism Gonadotrophin excess menstrual disorders and infertillity
- 24. Consequences: Excessive Secretionof prolactin secretion of GnRH gonadotrophins In men: impotency, decreased libido In women: amenorrhea, galactorrhea b) Excessive Secretion of somatotrophine (growth hormone ) acromegaly (in adults) gigantism (in adolescents whose epiphyseal plates have not yet closed)
- 25. b)-continuing Pathomechanisms involved : The usual GH baseline secretion pattern is lost (as are sleep – related GH peaks) - A totally unpredictable secretory pattern of GH occurs GH secretion is slightly elevated somatomedin stimulation of growth (in adolescent) - C onnective tissue proliferation - B ony proliferation characteristic appearance of acromegaly - P hosphate reabsorbtion in renal tubules hyperphosphatemia - I mpairement of carbohydrate tolerance - M etabolic rate H yperglycemia - it is a result of GH inhibition of peripheral glucose uptake and increase hepatic glucose production compensatory hyperinsulinism insulin resistance diabetes mellitus In adult s :
- 26. c) ExcessiveSecretion of corticotrophin ( ACTH) central form of Cushing syndrome (Cushing disease) Causes: micro- or macroadenomas of adenohypoph y sis, hypothalamic disorders Pathophysiology: C hronic hypercortisolism is the main disturbance of ACTH Symptoms and signs: weight gain: - accumulation of adipose tissue in the trunk, facial, and cervical areas (truncal obesity, moon face, buffalo hump) - weight gain from Na and water retention glucose intolerance DM type 2 polyuria: osmotic polyuria due to glycosuria
- 27. Protein Wasting : due to catabolic effects of cortisol on peripheral tissue (muscle wasting muscle atrophy and weakness thin lower extremities ) in bone: - loss of protein matrix osteoporosis - blood calcium concentration renal stones in skin: - loss of collagen thin, weakened integumentary tissues purple striae; rupture of small vesels thin, atrophic skin is easily damaged, leading to skin breaks and ulceration Hyperpigmentation: due to very high levels of ACTH - manifestation in: mucous membranes, hair, and skin Hypertension: results from permissive effect of cortisol on the actions of the catecholamines (KA) vascular sensitivity to KA vasoconstriction hypertension
- 28. Suppression of theimmune system susceptibility to infections alteration of mental status - from irritability and depression up to schizophrenia symptoms and signs of adrenal androgen s level in women: - hair growth (especially facial hair) - acne - oligoamenorrhea - changes of the vois hyperglycemia, glycosuria, hypokalemia, metabolic alkalosis Excessive Secretion Of Thyreotrophin and Gonadotrophins is rare
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- 30. Measurement of anteriorpituitary hormones Measured in serum by immunoassay Pulsatility of secretion of some of these hormones makes inappropriate to rely on single measurements for diagnostic purposes Dynamic tests/ functional tests are important tools in ix. pituitary functions and other endocrine organs. Basic principle of dynamic tests: Hypofunction - stimulation tests Hyperfunction-suppression tests
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- 33. Treatment 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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