Supervisors: Prof. Majde Al-BarbaryDr. Mohammed El-Adel

Students Name:Ahmed Al-Zahrani

Asem Al-Slamah

Ali Al-ManiFahad Al-Habib

Posterior pituitary

disorders

Objectives:

• 1- Anatomy & histology of pituitary gland.• 2- Types of posterior pituitary disorders.• 3- Sign & symptoms.• 4- Investigations.• 5- Causes.• 6- pathophysiology.• 7- management.

Anatomy & Histology of the Pituitary Gland

• Pituitary Gland called : “ Master Gland “ Or “ Hypophysis Cerebri Gland “ .

• Location : in a cavity of the sphenoid bone (sella turcica) at the base of the brain below hypothalamus .

• Pituitary gland consists of 2 lobes : 1- Anterior , called : Adenohypophysis .2- Posterior , called : Neurohypophysis .

( because it's connected to brain by stalk called : infundblum )

Anterior Pituitary Gland

Consist of : 1 -pars distalis

2 -pars intermedia

3 -pars tuberalis

1- Paris Distalis :

• The largest in the anterior portion.• Cells in the paris distalis are : • Chromophils: Acidophilic (Red stain) or Basophilic (Blue

stain). A- Acidophils: Somatotrophs cells and Lactotrophs cells

(Secrete: Growth Hormones and Prolcatin) B- Basophils: Gonadotrophs cells, Corticotrophs cells and

Thyrotrophs cells. (Secrete: LH, FSH, ACTH, TSH )

• Chromophobes : no stain (have no granules or few granules)

2- Pars intermedia :

• Consist of basophilic cell .• In certain species, melanocyte stimulating

hormone (MSH) may be secreted by the pars intermedia.

3- Pars Tuberalis :

• Surrounds the cranial parts of the infundibulum of neuohypophysis.

• It is composed of cuboidal basophilic cells.• Most of cells secrete gonadotrophs ( LH , FSH )

.

Function:• neurosecretion is formed in hypothalamus,

stored in pars nervosa to be secreted into blood capillaries.

• Neurons of the paraventricular nucleus manufacture Oxytocin.

• Neurons of the supraoptic nucleus manufacture Antidiuretic Hormone (ADH)

Relations of the pituitary gland:

• Superior: Brain, diaphragma sellae.• Inferior: sphenoid air sinuses.• Anterior: sphenoid sinus • Posterior: Pons , dorsum sellae, basilar artery.• Laterally: cavernous sinus.

Blood supply:

Arteries: (1) Superior and (2) Inferior hypophyseal arteries : branches of : internal carotid artery .

Veins: Drain to : intravenous sinus.

Hormone Anterior (Front Part)

Target Function

Adrenocorticotrophic Hormone (ACTH)

Adrenals Stimulates the adrenal gland to produce a hormone called Cortisol. ACTH is also known as corticotrophin.Cortisol promotes normal metabolism, maintains blood sugar levels and blood pressure. It provides resistance to stress and acts as an inflammatory agent. Cortisol also helps to regulate fluid balance in the body.

Thyroid stimulating hormone (TSH)

Thyroid Stimulates the Thyroid Gland to secrete its own hormone called Thyroxine (T4). TSH is also known as thryrotropin. Another hormone produced from the thyroid is called tri-iodothyronine or T3. Thyroxine controls many bodily functions, including heart rate, temperature and metabolism. It also helps metabolise calcium in the body

Cont ..Lutenising Hormone (LH)And Follicle- Stimulating Hormone (FSH)

Ovaries (females)

Testes (males)

Control reproduction and sexual characteristics. Stimulate the ovaries to produce Oestrogen and Progesterone and the testes to produce Testosterone and sperm. LH and FSH are also known collectively as gonadatrophins.Oestrogen helps with growth of tissue of the sex organs and reproductive parts. It also strengthens bones and has a positive effect on the heart. Testosterone is responsible for the masculine characteristics including hair growth on the face and body and muscle development. It is essential for producing sperm and strengthening the bones.

Prolactin Breasts Stimulates the breasts to produce milk and is secreted in large amounts during pregnancy and breastfeeding. It is however present at all times in both males and females.

Cont..Growth Hormone (GH)

All cells in the body In children this hormone is essential for a normal rate of growth. In adults it controls energy levels and well-being. It is important for maintaining muscle and bone mass and appropriate fat distribution in the body.

Hormone Posterior (Back Part)

Target Function

Antidiuretic Hormone (ADH)

Kidneys Controls the blood fluid and mineral levels in the body by affecting water retention by the kidneys. This hormone is also known as Vasopressin

Oxytocin Uterus Breasts

Affects the uterine contractions in childbirth and the subsequent release of milk for breast feeding.

Sign & symptomsThe most common symptom of diabetes insipidus are:

– Polydepsia – Polyuria – Nocturia & bed-wetting

• Infants and young children who have diabetes insipidus may have the following signs and symptoms:– Unexplained fussiness or inconsolable crying – Unusually wet diapers – Unexplained fever – Dry skin with cool extremities

Cont..

• Diabetes insipidus can cause dehydration which can cause:– Dry mouth – Muscle weakness – Hypotension (low blood pressure) – Sunken appearance of the eyes

• Rapid heart rate • Weight loss • Diabetes insipidus can also cause an electrolyte imbalance

(Hypernatremia& hyperchloremia)• Electrolyte imbalance can cause symptoms such as headache,

fatigue, irritability and muscle pains• Seizure secondary to Hypernatremia can happen

Investigations • Some of the tests that commonly use to determine the type of

diabetes insipidus and in some cases, its cause, include: • Water deprivation test. This test helps determine the cause of

diabetes insipidus. You'll be asked to stop drinking fluids two to three hours before the test so that your doctor can measure changes in your body weight, urine output and urine composition when fluids are withheld. In some cases your doctor may also measure blood levels of ADH during this test.

• The water deprivation test is performed under close supervision in children and in pregnant women to make sure no more than 5 percent of body weight is lost during the test.

Cont..

• Urinalysis. Urinalysis is the physical and chemical examination of urine. If your urine is less concentrated (meaning the amount of water excreted is high and the salt and waste concentrations are low), it could be due to diabetes insipidus.

• Magnetic resonance imaging (MRI) scan. An MRI of the head is a noninvasive procedure that uses powerful magnets and radio waves to construct detailed pictures of brain tissues. Your doctor may want to perform an MRI to look for abnormalities in or near the pituitary gland.

SIADH is characterized by:

– fluid retention– serum hypo-osmolarity– dilutional hyponatraemia– hypchloremia– concentrated urine in the presence of normal or

increased intravascular volume– normal renal function

• Laboratory findings in diagnosis of SIADH include-• Hyponatremia <130 mEq/L, and POsm <270 mOsm/kg. • Other findings include-• Urine sodium concentration >20 mEqlL (inappropriate natriuresis).

Urine sodium concentration may be normal reflecting dietary intake. • Maintained hypervolemia • Suppression of renin-angiotensin system • No equal concentration of atrial natriuretic peptide • Low blood urea nitrogen (BUN) • Low creatinine • Low uric acid • Low albumin

Pathophysiology

DI

• ADH is the primary determinant of free water excretion in the body. Its main target is the kidney, where it acts by altering the water permeability of the cortical and medullary collecting tubules. Water is reabsorbed by osmotic equilibration with the hypertonic interstitium and returned to the systemic circulation.

Cont..

• The actions of ADH are mediated through at least 2 receptors: V1 mediates vasoconstriction, enhancement of corticotrophin release, and renal prostaglandin synthesis; V2 mediates the antidiuretic response.

SIADH• The key to the pathophysiology, signs,

symptoms, and treatment of SIADH is to understand that the hyponatremia is a result of excess water and not a serum sodium deficiency. SIADH consists of hyponatremia, inappropriately elevated urine osmolality (>200 mOsm/kg), excessive urine sodium (UNa >30 mEq/L), and decreased serum osmolality.

Cont..

• These findings occur in the absence of diuretic therapy; in the presence of euvolemia without edema; in the setting of otherwise normal cardiac, renal, adrenal, hepatic, and thyroid function; and in absence of factors known to stimulate ADH secretion such as severe pain, hypotension, and stress.

Cont..• In SIADH, the inappropriately elevated level of

vasopressin enhances the reabsorption of water, thus concentrating the urine. It is the excess free water absorption that causes hyponatremia.

Management

• 1- Medication.• 2- Radiotherapy.• 3- Surgery.

1- Medication• 1- desmopressin or lypressin.• 2-Carbamazepine.• 3- Diuretic hydrochlorothiazide (a thiazide

diuretic) or indomethacin.• + Amiloride to prevent hypokalemia.

• The sign and symptoms of uncomplicated DI can be eliminated completely by treatment with DDAVP (Desmopressin), that act selectively at V2 receptors to increase urine concentration and decrease urine flow.

• It’s usually taken by nasal spray.• Pituitary DI can also be treated by with chlorpropamide

(Diabinese) with the same mechanism.• The symptoms and signs of nephrogenic DI are not

affected by treatment with DDAVP or chlorpropamide but maybe reduced by treatment with a thiazide diuretic with a low sodium.

2- Radiotherapy• Radiotherapy is delivered using high-energy X-

ray machines, called linear accelerators (Linacs) which are similar to CT scanners. They focus an X-ray beam onto the pituitary tumour and surrounding area, from several different angles, one at a time.

• Normal body cells are better able to repair radiation damage than tumour cells and by delivering the radiotherapy using repeated small dose treatments; the chance of permanent damage to your own normal body cells is reduced. In addition, by giving many small treatments, the total dose that can safely be delivered to the tumour is higher, thus increasing the chances of success.

radiotherapy is considered for patients:

• Who have evidence of persisting tumour outside the pituitary fossa (the space where the pituitary gland sits) following surgery.

• Whose tumour is secreting a hormone that continues to be raised in blood tests following surgery despite treatment with drugs.

• Whose pituitary tumour re-grows (this would be some time after surgery, perhaps following a second operation).

3- Surgery

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