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
Compare the causes of excess prolactin if;
- Prolactin> 5000
- Prolactin< 5000
Prolactin>5000: Likely due to a prolactinoma
Prolactin<5000: Might be due to “Stalk effect”
What 2 kinds of effects are possible with GH secreting pituitary adenomas
Typically large so;
- Mass effects (Headaches, visual field defects)
- Systemic effects (Via both GH and IGF-1)
Name 7 physical effects of GH Excess
- Broad nose
- Coarse facial features
- Thick lips and prominent supraorbital ridge
- Enlargment of hands and feet
- Greasy skin
- Excessive sweating
- Voice deepens (Hypertrophy of soft tissues upper airway)
GH antagonises the actions of insulin.
What can it lead to?
What condition can happen due to ACTH excess
Can lead to development of Diabetes Mellitus
Excess ACTH-> Cushing’s syndrome
Name 3 Treatments for Acromegaly
- Surgery to remove adenoma
- Radiation therapy
- Drug therapy
Name 3 drugs used to treat acromegaly
Synthetic somatostatin (Natural has very short half life)
GH receptor antagonists (Pegvisomant)
Dopamine receptor agonists (Some use, Need a higher dose than for treating prolactinomas)
