Pituitary Disorders Flashcards
What is the most common cause of pituitary malfunction?
Compare Functioning and Non-functioning pituitary tumours. Which is rarer?
A benign tumour (Adenoma)
Functioning: A tumour where the tumour cells make 1/ more hormone leading to overproduction. (Rarer)
Non-functioning: A tumour where the tumour cells don’t produce any hormone
Explain 1 hormone production abnormality caused by pituitary non-functional tumours
Explain 4 clinical signs of a Pituitary non-functioning tumour
- Inadequate production of 1/ more pituitary hormones due to physical pressure from the growing tumour on glandular tissue
Pressure on surrounding structures in the tumour’s vicinity;
- Headaches
- Visual problems
- Vomiting
- Nausea
What kind of symptoms do you get with a Functioning-tumour
Systemic effects of the over secreted hormone
What are 3 components involved in the investigation of a suspected pituitary tumour
- Delineation of the anatomy, size and topographical location of the mass
- Assessment of visual field defects
- Assessment of endocrine function (To determine if there is a hormonal excess or deficiency)
One aspect of investigation of a suspected pituitary tumour is Assessment of endocrine function.
What are 2 ways this can be done
- Measuring hormone levels in blood
- Staining a biopsy of the tumour with antibodies for the relevant hormone
How do you test the;
- Thyroid axis
- Prolactin axis
- Gonadal axis
Thyroid axis;
- Measure TSH, Free T4 (Thyroxine)
- Basal blood test
Prolactin axis;
- Measure serum prolactin
- Basal blood test
Gonadal axis;
- Measure LH, FSH, Testosterone, Oestradiol
- Basal blood test
How do you test the;
- HPA Axis
- Growth Hormone Axis
HPA Axis;
- Measure cortisol
- Dynamic blood test
GH Axis;
- Measure GH, IGF-1
- Dynamic blood test
Compare Basal and Dynamic Blood Tests
Basal:
- Single blood test used as a measurement
Dynamic:
- 2 or more blood tests used as a measurement
- Involve suppressing OR stimulating a particular hormonal axis
If you suspect a hormonal deficiency, what dynamic test do you perform to asses the hormonal axis?
What if you suspect a hormonal excess?
If suspected hormone deficiency, perform a stimulation test
If suspected hormone excess, perform a suppression test
What is Hypopituitarism?
What is it most commonly a result of? Name 3 Other causes
Hypopituitarism: Insufficient pituitary hormones production
- Most commonly, due to a pituitary adenoma
- Radiation therapy
- Inflammatory disease
- Head injury
What is the typical way a pituitary adenoma leads to Hypopituitarism?
Progressive loss of anterior pituitary function, with GH and LH/FSH usually the first hormones to be affected
What do you call deficiency of ALL anterior pituitary hormones?
What are the 2 occasions when secretion of ADH and Oxytocin are significantly affected by a pituitary adenoma?
Panhypopituitarism
- If tumour affects hypothalamic function
- If an inflammatory process is involved
How prominent are the symptoms of GH deficiency in ADULTS?
List 4
Symptoms are quite subtle
- Decreased tolerance to exercise
- Decreased muscle strength
- Increased body fat
- Reduced sense of well being
Why is GH deficiency hard to diagnose?
How do we counter this?
Hard to diagnose as GH secretion is pulsatile
Use a combination of direct and indirect measurements
Compare the causes of GH deficiency in adults and children
In children;
- Typically idiopathic
- Suspected causes: Gene mutation, autoimmune inflammation
In adults;
- Usually due to mass effects from a pituitary adenoma
Suggest 1 treatment of GH deficiency
GH therapy with recombinant human GH
What do you call Gonadotropin deficiency? What is it usually caused by
List 4 symptoms in women of reproductive age
List 2 symptoms in men
Hypogonadism, usually due to mass effects from a pituitary adenoma
In women of reproductive age;
- Lack of libido
- Infertility
- Oligomenorrhea (Infrequent menstrual periods) OR
- Amenorrhea (Absence of menstruation)
In men;
- Lack of libido
- Impotence
List 6 causes of ADH deficiency
- Hypothalamic tumour
- Pituitary tumour that’s extended up into hypothalamus
- Infections (Such as meningitis)
- Autoimmune infiltration
- Pituitary surgery
- Cranial radiotherapy
What is the main consequence of ADH deficiency
Diabets Insipidus- Characterised by excess excretion of dilute urine, polydipsia and dehydration
What are 3 main conditions caused by hyperpituitarism
- Prolactin excess
- GH excess
- ACTH excess
What is the most common form of pituitary disorder?
List 5 symptoms it can cause
Hyperprolactinaemia (High prolactin level)
- Galactorrhoea (Unexplained milk production, rare in men)
- Gynecomastia (Hard breast tissue)
- Hypogonadism (Reduced activity of testes/ ovaries)
- Amenorrhea
- Erectile Dysfunction
How does hyperprolactinaemia lead to hypogonadism in 3 steps
- High plasma prolactin
- High dopamine level (PIH) (Negative feedback)
- Inhibited GnRH-> Inhibited FSH and LH secretion
What’s the most common cause of hyperprolactinaemia?
Name 5 other causes
Prolactinoma (pituitary adenoma that secretes prolactin)
Physiological causes;
- Pregnancy
- Suckling
- Stress
- Exercise
- Drugs (Antidepressants, antipsychotics)
What is prolactin secretion mainly under the influence of?
What is the primary treatment for Prolactin excess?
Name 2 others
Negative influence of Dopamine
Dopamine receptor agonists (Cabergoline)
- Radiotherapy
- Trans-sphenoidal surgery
