16 - Pituitary Disorders Flashcards
What can non functioning pituitary tumours do to the pituitary gland?
- Inadequate production of pituitary hormones due to pressure from tumour growing on glandular tissue
- Pressure on surrounding structures of the tumour causing symptoms such as headaches
What are some symptoms of a non-functioning pituitary tumour?
- Headaches
- Visual problems due to compression of optic nerve
- Vomiting
- Nausea
What are symptoms of hyper secreting (functional) pituitary tumours?
- Rare but problems due to overproduction of one or more of the pituitary hormones
- Symptoms due to systemic effect of the hormone being over produced but may not be seen due to negative feedback
How do you investigate a suspected pituitary tumour?
- Look at the anatomy, size and topographical location of the mass by MRI
- Assessment of visual field defects
- Assessment of endocrine function to determine if hormone excess or deficiency
How do you measure hormone levels in the blood to test for a hypersecreting pituitary tumour?
- Staining sections from biopsy of the tumour with antibody for the hormone
- Measure blood levels
What are causes of hypopituitarism?
- Mainly pituitary adenoma causing secondary effect
- Radiation therapy
- Inflammatory Disease
- Head injury
What are the first hormones to be affect in hypopituitarism?
- Progressive loss of anterior pituitary gland function
- Starts with GH and LH/FSH
What is it called when all the hormones from the anterior pituitary gland are deficient?
Panhypopituitarism
When does hypopituitarism affect the posterior pituitary gland?
Only when the tumour affects hypothalamic function or inflammatory process involved
What are some symptoms of growth hormone deficiency in adults?
- Subtle
- Decrease in tolerance to exercise
- Decreased muscle strength
- Increased body fat
- Reduced sense of “well being”
How do you investigate GH deficiency?
Difficult as secretion is pulsatile, need lots of direct and indirect measurements, look at IGFs
What are the causes of GH deficiency?
- Adults: usually due to mass effect of pituitary adenoma
- Children: idiopathic but gene mutations and autoimmune inflammation could be a cause
What effect does GH deficiency have on children?
- Fetal: no effect on growth unless severe which can result in hypoglycaemia and jaundice
- 1 year to mid teens: poor growth and short stature
How can you treat GH deficiency?
Recombinant GH therapy
What are the symptoms and causes of gonadotropin deficiency?
- Hypogonadism due to mass effects of pituitary adenoma
- Women: lack of libido, infertility, oligomenorrhea or amenorrhea
- Men: lack of libido and impotence
What can cause ADH deficiency?
- Hypothalamic tumour
- Pituitary tumour extending into hypothalamus
- Cranial radiotherapy
- Pituitary surgery
- Autoimmune infiltration
- Infections like meningitis
What are some symptoms of ADH deficiency and what condition does it cause?
- Diabetes Insipidus
- Dehydration
- Polydipsia
- Polyuria
What symptoms can hyperprolactinaenia present with?
- Galactorrhea
- Gynecomastia
- Hypogonadism
- Amenorrhea
- Erectile dysfunction
What are the causes of hyperprolactinaemia?
- Prolactinoma
- Pregnancy and suckling
- Stress and exercise
- Antipsychotics (haloperidol as dopamine antagonist) -
- Antidepressants
How is hyperprolactinaemia treated?
- Cabergoline (dopamine agonist) is first line
- Trans-sphenoidal surgery (rare)
- Radiotherapy
MEASURE PROLACTIN LEVELS BEFORE SURGERY ON PITUITARY GLAND
What is one of the causes of Cushing’s syndrome related to the pituitary gland?
ACTH excess
What are the symptoms of growth hormone excess in adults?
- Headache, visual field defects and other cranial nerve pulsies as secreting adenomas tend to be large
- Takes several years (around 6) to manifest with:
broad noses, coarse facial features, thick lips, prominent supraorbital ridge, enlargement of hands and feet, greasy skin due to excess sweating, deep voice due to hypertrophy of soft tissues in air ways
What are the symptoms of growth hormone excess in children?
- Gigantism not acromegaly
- Growth in long bones where epiphyseal growth plates not fused
What other disorders can be caused from a growth hormone excess?
- Diabetes mellitus (GH antagonises insulin actions)
- Increase IGF-1 associated with cancer
What are the treatment options for acromegaly?
- Surgery to remove adenoma
- Radiation therapy
- Drug therapy with dopamine receptor agonists
What drugs are used to treat acromegaly?
- GH receptor antagonists like Pegvisomant are main drug
- Not somatostatin as short half life but analogs with long half like produced
- High dose dopamine receptor agonist
What is diabetes insipidus?
What is pituitary apoplexy?
- Sudden vascular event in a pituitary tumour
- Sudden onset headache, double vision, cranial nerve palsy, visual field loss and hypopituitarism (cortisol deficiency is the most dangerous). Apoplexy needs prompt diagnosis and treatment
