Endocrinology Flashcards
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
What is LADA?
latent onset diabetes of adulthood
autoimmune diabetes
autoimmune cell failure is slow (much slower than T1DM) - takes longer to become insulin dependent
anti-GAD antibodies are present
What ranges are diagnostic diabetes?
HbA1c: >48 mmol/mol (but not for 1st diagnosis)
Randon glucose: >11mmol/L
Fasting glucose: >7mmol/L
In patients that are asymptomatic, don’t diagnose based on one reading. repeat it.
Management of diabetes
- refer to diabetes/endo for individualised care plan
- provide advice and support e.g. Diabetes UK
- provide advice on lifestyle measures
- offer immunisations (influenza and pneumococcus)
- HbA1c monitoring 3-6 monthly
- eye/kidney/foot monitoring
- monitoring medical management
Drugs for T1DM
Insulin
education on self monitoring of glucose and optimal targets
(devices such as FreeStyle Libre, insulin pump)
What diabetic medication is good in pts with heart disease?
SGLT2 inhibitors
T2Dm meds
1st line: metformin
CVS/HF SGLT2i
add info to this
Management of DKA
ADMIT
IVF
IV insulin + potassium replacement
ix: urinalysis (ketones), blood gas shows acidosis (ketones high)
do DKA patients always need admission?
yes
management of HHS
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How is DKA and HHS different?
no ketones in HHS
learn ranges for Addison’s
- Fluids! (IV sodium chloride)
- VTE prophylaxis (hyperviscosity)
- insulin should only be given in blood sugars stop falling while giving IV fluids.
steroid induced vs addisons
paradoxically appear cushingoid
lack hyperpigmentation, high K+ and salt cravings
preserved MR activity secretion in GC induced addisons
Which O/E findings can help distinguish between primary and secondary adrenal insufficiency?
hyperpigmentation is primary (POMC -> ACTH + alpha MSH)
Management of Addison’s including doses, sick day rules
- Hydrocortisone (20-30mg/day in 2-3 divided doses with the majority taken in the first half of the day)
- Fludrocortisone
In intercurrent illness take double the dose of hydrocortisone
Also need a steroid card (alert/info)
weight gain DDx
Cushing’s syndrome / disease
PCOS
hypothyroidism
malignancy
Causes of Cushing’s
ACTH dependent:
- Cushing’s disease -
- ectopic ACTH (SCLC) - 10%
ACTH independent
Pseudo
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Ix for ?Cushing’s
give 1mg dex at night
if at 8 am you see cortisol spike -> Cushing’s
insert more info
IPSS
What is Nelson’s syndrome?
- also known as ‘post adrenalectomy syndrome’
- rare
- seen in pts post bilateral adrenalectoym
- pts who have an undeteced pituitary adenoma -> adrenals removed -> no -ve feedback from cortisol on the hypothalamus -> ↑ CRH production → uncontrolled enlargement of preexisting but undetected ACTH-secreting pituitary adenoma → ↑ secretion of ACTH and MSH → sx
- Symptoms: headache, bitemporal hemianopia (mass effect), cutaneous hyperpigmentation
Mx of hyperthyroidism
How do you differentiate Graves’ vs other causes of thyrotoxicosis?
Eye signs:
exophthalmos
proptosis
ophthalmoplegia
might also get derm signs
complications of hyperthyroidism
AF (common)
Congestive HF
bone loss
dermopathy
Schmidt’s syndrome
Addison’s + AI hypothyroidism + T1DM
What is the Zuckercandl organ?
Chromaffin body derived from the neural crest locaated at the bifurcaation of the aorta or the origin of the IMA
also known as para-aortic body
have the potential for deadly paragangliomas (surgical cause of HTN)
Management of hyperthyroidism in pregnancy according to TM
1st: Propylthiouracil (because there is a lower risk of congenital abnormalities, incl. facial malformations and VSD)
2nd and 3rd TM: carbimazole (due to lower risk of hepatotoxicity)
How do sulfonylureas work?
stimulate the release of insulin from the pancreas which can lower blood sugar levels (therefore they are associated with a risk of hypos - especially if the medication is not taken with food or if the patient is fasting)
What medication can you use in the management of primary hyperparathyroidism in patients that are not suitable for surgery?
cinacalcet
(it is a calcimimetic - a drug that ‘mimics’ the action of calcium on tissue by allosteric activation of the calcium-sensing receptor)
Precipitating factors for HHS
intercurrent illnesss
dementia
sedative drugs
What is exposure keratopathy and in which endocrine condition can it occur in?
= damage to the cornea du to dryness
can occur in thyroid eye disease (Grave’s disease) due to the inability to close eyes
Summarise the features of the MEN disorders?
MEN I
- Pituitary adenoma
- Parathyroid hyperplasia
- pancreas tumours
MEN IIa
- parathyroid hyperplasia
- phaeochromocytoma
- medullary thyroid carcinoma
MEN IIb
- phaeochromocytoma
- medullary thyroid carcinoma
- mucosal neuroma
- marfanoid body habitus
Zollinger-Ellison syndrome
= condition characterised by excessive levels of gastrin secondary to a gastrin-secreting tumour.
The majority of these tumours are found in the first part of the duodenum, with the second most common location being the pancreas.
- Around 30% of gastrinomas occur as part of MEN type I syndrome.
Features
- multiple gastroduodenal ulcers
- diarrhoea
- malabsorption
