Endocrine Flashcards
Too much growth hormone=?
acromegaly (adults) gigantism (paeds)
Not enough GH
pituitary dwarfism
Too much cortisol
Cushing’s disease if pituitary
Cushing’s syndrome if due to steroids/adrenal adenoma/paraneoplastic
What paraneoplastic tumour is often linked to cushing’s syndrome
Small Cell lung ca
Not enough cortisol
Adrenal insufficiency (primary/sec/tert)
Or congenital adrenal hyperplasia
Test for cushing’s?
Dexamethasone suppression test
Urinary free cortisol (3 times)
Late night cortisol
What are the causes of adrenal insuff?
primary- Addison’s (autoimmune), TB/fungal/HIV
Secondary- pituitary damage e.g. non-functioning adenoma
Tertiary- stopped LT steroids
Test for secondary adrenal insufficiency?
Insulin stress test/glucon stimulation
Test for acromegaly?
OGTT
Test for GH deficiency?
Insulin stress test
Too much adrenaline?
Phaeochromocytoma
Test for phaeochromocytoma?
plasma free metanephrins/24h urine catecholamines
Too much aldosterone?
Conn’s or secondary hyperaldosteronism
Causes of Conn’s
Adrenal adenoma/carcinoma
Bilat adrenal hyperplasia
Familial
Causes of secondary hyperaldosteronism?
Low renal BP- so RA stenosis/obstruction or heart failure
What would happen to renin in secondary hyperaldosteronism?
high
Do you get low adrenaline in adrenal insufficiency?
No- medullary sparing
What type of adrenal insufficiency does not effect aldosterone?
Secondary as it is under renin control, not pituitary
What electrolyte derangement do you get in primary adrenal insuff?
Low sodium, high potassium (as less aldosterone to retain sodium, and it is a K/Na pump so K not pumped out)
What electrolyte derangement do you get in secondary adrenal insuff?
Low sodium, normal potassium (aldosterone not involved, but cortisol has some action on sodium)
What is the effect of congenital adrenal hyperplasia on hormones?
Low cortisol
High testosterone
What is the pathophysiology of congenital adrenal hyperplasia?
Deficiency of 21-hydroxylase enzyme which catalyses the conversion of progesterone into aldosterone and cortisol, but is not involved in the conversion of progesterone to testosterone. So ALL of the progesterone becomes testosterone so high testosterone, low cortisol and aldosterone.
Inheritance of congenital adrenal hyperplasia
Autosomal recessive
Low ADH
SIADH
High ADH
diabetes insipidus
Test for diabetes insipidus
Water deprivation test
Desmopressin stimulation test
Pathophys of primary hyperparathyroid?
Parathyroid tumour
How do PTH and calcium change in primary hyperparathyroid
Both high
Pathophys of secondary hyperparathyroid?
Low vitamin D or CKD results in low calcium so high PTH to try and stimualte
Pathophys of tertiary hyperparathyroid?
Long term secondary leads to gland hyperplasia. When secondary is resolved then excess PTH and also calcium
What drug can you give in hyperparathyroid if surgery is inappropriate?
Cinacalcet to reduce PTH
How can you test to see if hyperparathyroid might cause kidney damage?
24h urine calcium
Causes of hypoparathyroid
Surgery, genetic, autoimmune, RT, tumour
What happens to calcium, phosphate and PTH in hypoparathyroid?
Calcium and PTH low
Phosphate high
What is the action of PTH on phosphate?
Makes the kidneys excrete it in the urine.
In general in endocrinology, if you think there is too much of a hormone being made what type of test do you do?
Suppression test
In general in endocrinology, if you think there is not enough of a hormone being made what type of test do you do?
Stimulation test
Test for primary adrenal insufficiency?
Short synacthen test
What is synacthen?
ACTH analogue
What visual field defect can you get in pituitary tumours?
Bitemporal hemianopia
What type of pituitary tumour might you treat medically? How?
Prolactinoma- give a dopamine agonist
Which cases of hyperthyroid should be referred to endo?
All
What order are hormones lost in in pituitary tumours?
GH, LH, FSH, TSH, ACTH, Prolactin
good luck for the annual paper
Can you give antithyroid drugs in toxic nodule/ multinodular goitre?
No- radioiodine or surgery
Why can you get increased alk phosph and calcium in Graves?
High bone turnover as everything is sped up in hyperthyroid
Most likely cause of high TSH
pituitary TSHoma
Name two antithyroid drugs
carbimazole
propylthiouracil
Can you do a block and replace regime for hyperthyroid in pregnancy?
No as foetus relies on maternal thyroxine- titrate instead
Carbimazole SE
Agranulocytosis
If multiple hormone deficiencies, which is replaced first?
Cortisol
T4 AKA
thyroxine
Intracellularly which thyroid hormone is converted to which?
T4 to T3
What are the two mechanisms for thyrotoxicosis?
- increased synthesis of TH (hyperthyroid)
2. increased release of TH from a damaged thyroid gland
Rx of thyroiditis?
Supportive, can give beta blockers and NSAIDs for Sx
What are the two mechanisms by which amiodarone induces thyrotoxicosis
Type 1 - high iodine content of the drug provides a substrate for excessive TH synthesis in patients with a previously silent MNG
Type 2- toxic effect of the drug on the thyroid gland- destructive thyroiditis - release of preformed TH
What cause of thyrotoxicosis has a tender goitre?
De Quervains/subacute thyroiditis
What are the causes of a diffuse goitre?
Graves
De Quervains
Post partum
Secondary/TSHoma
How do you differentiate between true cushings and pseudo cushings? (test)
insulin stress test
Electrolyte and acid-base imbalance in cushings?
Hypokalaemic metabolic alkalosis
Calcitonin is a tumour marker for what sort of thyroid cancer?
Medullary (originates from the parafollicular cells which produce calcitonin)
MEN1 has which cancers
parathyroid (hyperPTH, hypercalc)
pituitary
pancrease
MEN IIa has what cancers
Parathyroid
Phaeochromocytoma
Medullary thyroid
What gene MEN II?
RET oncogene for both types
MEN IIb has what cancers?
Phaeochromocytoma
Medullary thyroid ca
Plus marfanoid body habitus and mucosal neuromas
What gene for MEN type 1?
MEN1
T1DM blood glucose targets at waking and at other times in the day
5-7 mmol/l on waking
4-7 mmol/l before meals at other times of the day
Impaired fasting glucose represents what type of insulin resistance?
Hepatic
Impaired glucose tolerance represents what type of insulin resistance?
Muscle
Is impaired glucose tolerance or impaired fasting glucose more likely to progress to T2DM and heart disease?
Impaired glucose tolerance
Someone has impaired fasting glucose what is next step?
Offer OGTT
The first-line treatment for a phaeochromocytoma is?
Non-selective alpha blocker- phenoxybenzamine.
Why do you give alpha blockers before beta blockers in Rx phaeochromocytoma?
Otherwise can get hypertensive crisis
Antibodies in Graves
TSH receptor antibodies
Which babies get hyperthyroid?
Mother has Grave’s
Long term complications of untreated hyperthyroid?
Congestive HF
Osteoporosis
Which congenital abnormalities have an increased incidence of Hashimoto’s?
Down’s and Turner’s
5 drugs that cause hypothyroid
Antithyroid drugs (carbimazole, propylthiouracil)
Amiodarone (can cause hyper and hypo)
Lithium
alpha interferon
IL2
When can someone who’s had a total thyroidectomy expect to be hypothyroid?
2-4w
When can someone who’s had a SUB total thyroidectomy expect to be hypothyroid?
Majority within the first year. If euthyroid at one year then annual chance of hypo is 0.5-1%
May become transiently hypo at 4-8w but then recover
When can someone who’s had radioiodine therapy for Grave’s expect to be hypothyroid?
Majority within the first year. If euthyroid at one year then annual chance of hypo is 0.5-2%
If RT to neck causes hypothyroid how long does it take?
years, often preceded by subclinical
Does iodine deficiency or excess cause hypothyroid?
Both
Random diseases that can cause hypothyroid
Haemochromatosis
Sarcoid
Amyloidosis
Leukaemia
What is a paraneoplastic cause of hypothyroid?
Consumptive hypothyroidism - ectopic production of type 3 deiodinase from vascular/fibrotic tumours. This essentially inactivates T3/4 peripherally
What other serology changes might someone with hypothyroid have (other than TFT changes)
hyperlipidaemia
hyponatraemia
How do you start someone under 50 on levothyroxine?
Initially: 50-100mcg OD
Titrate: change by 25-50mcg 3-4weekly
Maintenance: 100-200mcg OD
How do you start someone over 50 on levothyroxine?
Initially: 25mcg OD
Titrate: change by 25mcg 3-4weekly
Maintenance: 50-100mcg OD
Why is levothyroxine prescribing different in >50
They might have IHD- levothyroxine increases myocardial O2 demand
Information for pts on levothyroxine- how to take
30 min before breakfast/caffeine/other meds
How often should TFTs be monitored on levothyroxine?
6 weekly until stable then annually
What are severely hypothyroid patients who get an infection/cold exposure/trauma/take opioids at risk of
Myxoedema coma
Presentation myxoedema coma
Coma
Hypothermia
Hypercapnia
Hyponatraemia
Bradycardia
Rx myxoedema coma
IV liothyronine
Fluids
+IV hydrocort until r/o concurrent adrenal insuff
ICU- ?ventilator
Correct hypothermia
Treat cause
Can you give levothyroxine as normal in a suspected adrenal insufficiency patient?
Do a short synacthen test as may precipitate addisonian crisis- if confirmed to have then give hydrocort as well
Do you replace thyroid hormones in subclinical hypothyroid?
Only if:
Pregnant
Serum TSH >10
Goitre
Symptomatic
High serum antiTPO antibodies
If you don’t initially treat a subclinical hypothyroid do they require follow up?
Yes keep monitoring to see if become overt
Affect of oestrogen therapy on levothyroxine?
Can increase need for levo
If someone is fasted for surgery should they still have levothyroxine replacement?
Only if they need to be fasted for >5-7days- then you give it IV at 80% the oral dose.
In transient hypothyroid following thyroiditis do you treat?
only if symptomatic
what is metabolic syndrome?
Clustering of CVD risk factors, underlying pathology
may be related to insulin resistance
Can metabolic syndrome affect lean individuals?
Yes
What things are used in diagnosing metabolic synd in adults?
at least 3 of:
Waist circ
Triglycerides
HDL
BP
Fasting glucose
What percentage of thyroid nodules are malignant and in whom is the risk increased?
5%
<20/>70yo
Thyroid nodule with what other signs should prompt a 2ww?
Regional lymphadenopathy
Child
Voice changes
RT Hx
Persistent pain
FHx endocrine cancer
What could sudden pain in a thyroid nodule indicate?
Sudden bleed into cyst
is the diurnal variation of cortisol maintained in cushings?
No
Cushing’s disease is what?
Pituitary adenoma secreting excess ACTH
Once a patient has abnormal urinary cortisol/dex suppression/late night cortisol tests, what needs to be done?
Test to determine cause:
-Plasma ACTH (high=ACTH dependent i.e. pituitary or paraneoplastic ACTH production)
Plus MRI pituitary etc as indicated
Most reliable test of cause is inferior petrosal sinus sampling
what electrolyte metabolic imbalance in cushing’s
hypokalaemic metabolic alkalosis
6 causes of cushings syndrom
ACTH dependent: 1. pituitary adenoma, 2. ectopic ACTH from a tumour eg lung ca
Non-ACTH dependent: 3. adrenal adenoma, 4. adrenal carcinoma, 5. excess glucocorticoid medication, 6. rare- micro/macronodular adrenal hyperplasia
Rx cushing’s caused by ectopic ACTH from tumour
Excise tumour
If no remission after this - ketoconazole/metyrapone
Rx cushing’s caused by pituitary adenoma
- transphenoid surgery ±stabilisation beforehand with ketoconazile/metyrapone ±adjuvant RT
- if refractory- bilateral adrenalectomy or medical adrenalectomy with mitotane
Rx cushing’s caused by adrenal adenoma
unilat adrenalectomy
Rx cushing’s caused by adrenal carcinoma
unilat adrenalectomy + mitotane
What do ketoconazole/metyrapone do?
Stop cortisol synthesis
How do you treat diabetes/HTN caused by cushings?
As normal
