Pituitary Gland Disorders Flashcards
How is the pituitary gland supplied with blood
- short and long pituitary arteries
-hypophyseal portal circulation that begins at the capillary plexus around the arc
It has a dual blood supply
What hormones are secreted by the anterior pituitary gland
- ACTH : regulation adrenal cortex
- TSH : thyroid hormone regulation
-GH :growth hormone
-LH/FSH: reproductive control
-PRL:breast milk production
What hormones are secreted by posterior pituitary gland
-oxytocin
-Adh
Where is the pituitary gland found
-below brain in the sella turcica
Three layers of the endocrine system
Primary layer - end organ
Secondary -pituitary gland.
Tertiary - hypothalamus
3 factors to consider in pituitary tumours
-hormone hyper secretion
-space occupying lesion - lead to headaches , visual loss ,
-hormone deficiency states - interference with normal surrounding pituitary
What is an excess of GH called
Acromegaly
Excess of ACTH called?
Cushings disease
Excess of TSH?
Secondary thyrotoxicosis
Excess of FH/LSH
Non functioning pituatary tumour
Excess PRL .
Prolactinoma
What are some systemic effects growth hormone excess
- acral enlargement- hands and shoe size increase
Macroglossia m- large tongue
Carpal tunnel syndrome
-increased skin thickness
-increased sweating
-change in appearance
-insulin resistance
-diabetes mellitus
-increased triglycerides
-reduced total cholesterol
-increased nitrogen retention
Consequences in the cardiovascular system from excess growth hormone
-cardiomyopathy
-hypertension
-bowel polyps
-colon cancer
-multinoduler goiter
-hypogonadism
-arthropathy
-
What is prolactinomas
- high levels of prolactin which stimulates the production of breast milk
Tonic release of dopamine inhibits PRL release
Mechanical stimulation for nipple sends neural signal to the brain which stops dopamine production instantly , which leads to a large surge in prolactin to provide milk for the baby
Role of prolactin
Inhibits production of LH and FSH so that all the energy is given to the baby that is being breast fed
What drugs interfere with dopamine and prolactin
- antiemetics
- antipsychotic
-OCP/HRT
Features of PRL excess
-infertility
-reduced libido
-erectile dysfunction
-amenorrhoea
-oligoamenorrhoea
Treatment for excess prolactin
Dopamine agonists
-bromocriptine
-cabergoline
Non functioning pituitary tumours ; symptoms and treatment
30% of all pituitary tumours
Causes symptoms due to space occupation:
-headaches
-visual field defects
- nerve palsies
Treatement is surgery - radiotherapy
Treatment of pituitary adenoma
- surgery through the nose
-radiotherapy- slow
Drugs - stop hormone release , and block hormone production
Causes of pituitary failure
- tumour
-trauma
-infection
-inflammation
-Iatrogenic -illness caused by medical examinations
Symptoms of lack of thyroid production
-bradycardia
-weight gain
-cold intolerance
-hypothermia
-constipation
Symptoms when there is Lack of sex steriod
- oligomenorrhoea -period reduced
-reduced libido- less sex drive
Hot flushes
Reduced body hair
Symptoms of reduced cortisol
-tiredness
-weakness
-anorexia
-postural hypotension
-myalgia
Symptoms of reduced GH
-tired
-central weight gain
SIADH ( syndrome of inappropriate ADH)
excessive release of antidiuretic hormone (ADH) from the pituitary gland
Leads to brain infection /injury
-leads to water retention and dilutional hyponatremia
-sodium concentration in blood falls below normal
Diabetes insipidus
-polydipsia
-polyuria
Body unable to regulate water balance due to insufficient production of ADH
Excessive thirst
Urination
Two types of diabetes insipidus
CDI -deficiency or lack oc production of ADH , caused by damage to hypothalamus or pituitary gland
NDI- kindeys fail to respond to ADH even when ADH levels are normal or elevated , caused by inherited gene mutations , kidney disease , electrolyte imbalance
Water deprivation test
-assess body ability t concentrate urine and regulate water balance
- differentiate between CDI and NDI by evaluating kidney response to dehydration and water restriction
Stimulate release of ADH
dehydration usually leads to release of ADH which leads to water reabsorption by kidneys
Preparation: Before the test, baseline measurements of body weight, urine volume, urine osmolality (concentration), and serum electrolytes are obtained. Blood tests may also be performed to assess ADH levels, serum osmolality, and electrolyte levels.
Fluid Restriction: The patient is instructed to restrict fluid intake for a specified period, typically overnight or for several hours. This step induces dehydration and stimulates the release of ADH.
Monitoring: Throughout the test, the patient’s weight, urine output, and urine osmolality are monitored at regular intervals, usually every hour or two. Blood samples may also be collected periodically to measure serum osmolality, electrolytes, and ADH levels if available.
Criteria for Test Termination: The test is typically terminated when certain criteria are met, such as a significant increase in urine osmolality (>50%) from baseline or a specified level of dehydration (e.g., 5-6% body weight loss). If the patient becomes severely dehydrated or experiences significant symptoms, the test may be stopped earlier, and fluids administered as needed.
Interpretation of Results:
Normal Response: In individuals with normal water balance and ADH function, dehydration leads to an increase in urine osmolality (>800 mOsm/kg), indicating concentrated urine, and minimal weight loss (<5-6%).
Central DI: In CDI, dehydration does not result in a significant increase in urine osmolality despite water restriction, indicating the inability to concentrate urine despite elevated ADH levels. ADH levels may be low or normal.
Nephrogenic DI: In NDI, dehydration may lead to a modest increase in urine osmolality, but it remains below normal levels (<300 mOsm/kg), indicating impaired kidney response to ADH. ADH levels may be elevated.
