Hyposecretion of anterior pituitary hormones Flashcards
What is primary endocrine gland disease?
When it caused by disorder of the endocrine gland
What is secondary endocrine gland disease?
When it is caused by disorder of the anterior pituitary
What is tertiary endocrine gland disease?
When it is caused by disorder of the hypothalamus
What is panhypopituitarism?
Decreased production of all anterior pituitary hormones
How can panhypopituitarism be acquired? (6)
Tumours- hypothalamic and pituitary Radiation- damage Infection- meningitis Traumatic brain injury Infiltrative disease Inflammatory
How else can panhypopituitarism be caused?
Congenital (rare) or mutations (very rare)
How does panhypopituitarism usually develop?
In an adult with progressive loss of pituitary secretion>
What is the normal order of pituitary secretion loss?
Gonadotrophins
GH
Thyrotrophin
Corticotrophin
What are the three main types of panhypopituitarism?
Simmond’s disease
Sheehan’s syndrome
Pituitary apoplexy
What is the onset of Simmond’s like?
Insidious- very slow
What are the causes of Simmond’s? (5)
Infiltrative processes Pituitary adenomas Craniopharyngiomas Cranial injury Post surgery
What are the symptoms of Simmond’s mainly due to?
Loss of thyroidal, gonadal and adrenal function
What are the symptoms of Simmond’s?
Secondary amenorrhoea Impotence Loss of libido Tiredness Waxy skin Loss of body hair Hypotension
What is different about Sheehan’s compared to the other two?
It is specific to women
How does Sheehan’s develop?
Develops acutely following postpartum haemorrhage resulting in pituitary infarction
How does the postpartum haemorrhage lead to pituitary infarction?
The blood loss results in vasoconstrictor spasm of the hypophysial arteries and this leads to ischaemia and necrosis of the pituitary
How does Sheehans and pituitary apoplexy compare?
Very similar but pituitary apoplexy is in men and women and just due to normal haemorrhages
How do you diagnose hypopituitarism?
You can’t measure hypothalamic hormones so you measure basal values of the plasma for pituitary or target endocrine gland hormones
Why will a single measurement not suffice?
Hypothalamic hormones are released in pulses
What test can you use to find out if a person is producing hormones at a normal level?
Stimulation test
What does a lack of somatotrophin cause in children and adults?
Pituitary dwarfism in children
Effects uncertain in adults
What are other causes of short stature in children? (6)
Genetic- Down's, Turner's, Prader Willi Malnutrition Emotional deprivation Systemic disease Malabsorption Endocrine disorders- Cushing's, hypothyroidism, GH deficiency
What are the acquired causes of GH deficiency in children? (6)
Tumours of the hypothalamus or pituitary Other intercranial tumours nearby (optic nerve glioma) Irradiation Head injury Infection or inflammation Severe psychosocial deprivation
What are the genetic causes of GH deficiency in children?
Congenital (rare) - Deficiency of hypothalamic GHRH
Mutations of the GH gene (very rare)
Developmental abnormalities
What controls GH at a hypothalamic level?
GHRH and somatostatin
What are most endocrine-related causes of short stature due to?
Decreased production of GHRH
What does GH stimulate the production of in the liver?
IGF-1 (insulin like growth factor) (liver is main source but is produced in many places)
What does IGF-1 do?
Mediate growth effects
What is laron dwarfism due to?
GH receptor defect
Explain how GH receptor defect leads to Laron dwarfism?
As a result IGF-1 levels are low as somatotrophin isn’t having an effect
What is the main presentation of Kallmann’s syndrome?
Hypogonadism and anosmia
What is Kallmann’s caused by?
Genetic defect where the neurones in the embryo that will go on to produce GnRH are unable to migrate to the hypothalamus so their hypothalamus lacks GnRH neurones
What other condition leads to hypogonadism and is a hypothalamic defect?
Prader Willi
What is the standard way of testing the ability of the pituitary to produce GH?
Stimulate GH production by inducing hypoglycaemia (The gold standard is insulin induced hypoglycaemia)
What is the main aim of pituitary deficiency treatment?
Restore homeostasis by replacing missing hormones
What does growth hormone therapy lead to in children?
Acceleration of linear growth
Decreased body fat
Which children respond better to growth hormone therapy?
Young and obese
What is a common problem with GH therapy?
They develop resistance (antibodies)
How is growth hormone therapy administered?
Subcutaneous or intramuscular
When is GH administered?
Daily- In the afternoon as levels are normally high at night anyway
What is the half life of GH like?
Short- 20 mins
What does GH work on hence what is its action duration like?
Protein synthesis so long
What are the adverse effects of GH?
Lipoatrophy at site of injection
Intracranial hypertension- headaches
Increased risk of cancer
What are the signs and symptoms of GH deficiency in adults?
Reduced lean mass Increased adiposity Increased waist:hip ratio Reduced muscle strength and bulk Decreased HDL and increased LDL Impaired psychological wellbeing
What are the 4 ways of diagnosing GH deficiency in adults?
Lack of response to GH stimulation test
GHRH and Arginine
Low plasma IGF-1
Low plasma IGF-BP3
