Endocrinology Flashcards
(55 cards)
Phaeochromocytoma - Definition and key facts
Catecholamine secreting tumour (typically in the adrenal medulla).
Most commonly occur in the 3rd-5th decade of life
- 10% malignant
- 10% bilateral
Can be familial (associated with MEN2a, MEN2b, NF1, VHL).
Paragangliomas are catecholamine producing tumours that originate from chromaffin cells (derived from the neural crest) in the autonomic ganglia)
Phaeochromocytoma - signs, symptoms and Ix findings
Symptoms: episodic BP crises with paroxysmal (throbbing) headaches, diaphoresis, heart palpitations, anxiety, abdominal pain, nausea and pallor.
Signs: HTN,
Investigation Findings:
- plasma catecholamines
- raised urinary metanephrines (e.g. vanillylmandelic acid -> have higher diagnostic sensitivity than plasma catecholamines)
Phaeochromocytoma - Management
- alpha block (phenoxyenzamine - competitive irreversible antagonist of adrenaline)
- beta block (propranolo)
- surgical removal of the tumour/adrenal gland
You alpha block first to prevent hypertensive crisis
Blood supply of the adrenals
superior, middle and inferior adrenal artery
Why are phaeochromocytomas dangerous and what life-threatening presentations can they cause?
can cause a dangerous surge of adrenaline
this can lead to:
- arrhythmias
- MI
- cerebral haemorrhage
- sudden death
What % of gynaecomastia is drug related?
25%
-> therefore always review the medication the patient is taking
What is neonatal gynaecomastia?
- due to placental transfer of maternal estrogens
- sex independent, and spontaneously resolves within a few weeks or months
Management of gynaecomasta
- stop causative drugs
- medication to fix hormone imbalance
- surgery
Which tests are useful in distinguishing between type 1 and type 2 diabetes?
C-peptide (low in type 1)
anti-GAD (glutamic acid decarboxylase) antibodies
What is type 3c diabetes?
What prescriptions do these patients need?
Can happen when the pancreas is damaged and stops producing enough insulin
can be as a result of: pancreatitis, pancreatic cancer, CF, haemochromatosis
patients present with lower GI sx (e.g. steatorrhoea, diarrhoea) and T1 diabetes sx (weight loss, can have hypoglycaemia) -> they have endocrine and exocrine dysfunction
they also don’t make glucagon so it needs to be prescribed.
- insulin, glucagon, creon
What is the general rule of thumb in prescribing insulin in T1 diabetes?
0.5 units / kg body weight
-> half should be long lasting, half should be the post meal doses
e.g. if someone weights 60 kg their total daily requirement is 30 U;
baseline long acting insulin: 15 U
5U with every meal (3 meals)
What acid base abnormality can be seen in Cushing’s syndrome?
hypokalaemia metabolic alkalosis
(increased potassium excretion; increased bicarbonate resorption in the tubules)
Sick day rules for adrenal hormone replacement
double the GC dose
keep normal MC dose
How can sarcoidosis cause diabetes insipidus?
sarcoidosis can result in the formation of granulomas in the pituitary gland which can lead to neurogenic diabetes insipidus
What are the metabolic risks of acromegaly?
increased risk of
- diabetes
- HTN
- vascular disease (incl. cerebral aneurysms)
-> raised morbidity
What causes acromegaly
benign pituitary adenoma causing excessive secretion of GH and IGF-1 (in adults; in children this would lead to gigantism, but in adults you don’t get linear growth because the epiphyses have fused)`
Investigations in ?acromegaly
IGF-1 levels
OGTT with GH measurement
cranial MRI (pituitary)
Main cause of death in acromegaly
cardiovascular disease
Pathophysiology of acromegaly
increased GH -> increased IGF-1 -> overstimulation of cell growth and proliferation
How can you measure GH to test for acromegaly?
Not random GH measurement! Pulsatile secretion, therefore a high measurement would not be helpful/diagnostic.
If ‘0’, it could exclude acromegaly
-> measure by doing OGTT; normally, this would suppress GH to zero. If there is no suppression or even an increase in GH, this suggests a somatotroph adenoma.
-> measure baseline GH and 2h GH
Management options for acromegaly
All patients should be discussed in the MDT
medical:
- dopamine agonists (some patients respond)
- somatostatin analogies (octreotide, lanreotide)
- GH antagonists (pegvisomant)
Surgery
- transsphenoidal adenomectomy
Radiotherapy
What is the best single test for acromegaly?
Serum IGF-1 concentration
How do you test for acromegaly?
- serum IGF-1 -> if elevated to OGTT; if normal, acromeglay is ruled out
- OGTT with baseline and 2h GH -> if GH is suppressed, acromegaly is ruled out. If GH not suppressed: acromegaly confirmed, conduct pituitary MRI to determine the source of excess GH
- pituitary MRI
adenoma -> confirmation of GH secreting adenoma
normal -> screen for an extra-pituitary cause
waterhouse friedrichsen syndrome
acute primary insufficiency of the adrenal gland most commonly caused by adrenal haemorrhage (commonly associated iwht meningococcal meningitis; rarer causes include DIC, endotoxic shock and septicaemia due to other pathogens).
can be fatal
treat the underlying cause, parenteral fluid therapy and management of disorders of sodium balance
