Endocrine Flashcards
Thyroid storm is an emergency, (can be fatal) how can it present?
NB: have high index of suspicion in pts with underlying overactive thyroid + precipitating event
-delirium
-severe tachycardia
-GI: D&V, dehydration
-v. high fever
(often after a precipitating event)
Name possible precipitating events that could lead to a thyroid storm?
- systemic insults (surgery, trauma, MI, PE, DKA..)
- discontinuing anti-thyroid meds
- excessive iodine
- radioiodine therapy
- pseudoephedrine and salicylate use
Name some differences between hyperthyroidism and thyroid storm. (NB: clinical fts are v similar)
- fever differentiates thyroid storm
- high output cardiac failure and new onset AF can also be present
What are the core features of thyroid storm?
thyrotoxicosis + altered mental status + fever
- tachycardia out of proportion to fever
- (cardio or GI signs can be present too)
How is thyroid storm diagnosed?
-a scoring system
if >45pts highly suggestive
-if <25 can be excluded
-between suggests impending poss
How is thyroid storm managed? Name some principles only
- stop synthesis of new TH
- halt release of stored TH
- prevent conversion of T4 -> T3
- control adrenergic symptoms
- control systemic decompensation w supportive therapy
Name how beta blockers are used to treat thyroid storm and their routes:
- IV propanolol (1mg, repeated in 5mins until desired effect)
- or oral propanolol 20-120mg 6hrly until heart rate under control
Other than propranolol what medications are used to treat thyroid storm?
- carbimazole 10-30mg/daily or propylthiouracil 75-100mg/three times/day
- iodide
- steroids (dexamethasone 2mg 6hrly)
How is iodide used to treat thyroid storm? What route?
- Lugol’s iodide solution: 4drops every 12hrs
- reduces the vascularity
- but effect only lasts 7-12days
Where in the hospital should a thyroid storm pt be looked after? Other than direct rx, what supportive care is important to monitor/attend to?
- High Dependency/ICU
- hydration
- temperature (cool pt down)
- anti-pyretics e.g paracetamol
- AVOID ASPIRIN
- multivitamins esp. THIAMINE
What is the logic behind the following in the management of pts with thyroid storm?
- -AVOID ASPIRIN
- multivitamins esp. THIAMINE
- AVOID ASPIRIN (causing release of TH from binding globulin)
- multivitamins esp. THIAMINE - important to correct the altered mental state
What it used pre-operatively in pts with thyroid storm to get their T4 down into the normal range before thyroidectomy.
-anti-thyroid medications: thionamide therapy, if not tolerated iodine may be used.
What is likely diagnosis in a 40yo Asian, with muscle weakness and hyperthyroidism, unwell after a vigorous workout
Thyrotoxic periodic paralysis
When can Thyrotoxic periodic paralysis occur? What is the type/pattern of weakness?
- follow a vigorous exercise or a v high carb meal
- you get flaccid ascending paralysis (proximal->distal)
- spares facial and respiratory muscles
- depressed/absent Deep Tendon Reflexes due to weakness
What is the biochemical cause of Thyrotoxic periodic paralysis?
low serum K+ (aka thyrotoxic hypokalaemic periodic paralysis)
-thyrotoxicosis +
more adrenergic activity, high carb meal/high insulin, increase Na+/K+ ATPase activity, decreases K+ leading to paralysis
What is the management of Thyrotoxic periodic paralysis and why?
-B blocker e.g. propranolol 60mg inhibits Na/K ATPase
-replace potassium
-treat hyperthyroidism
AVOID IV glucose - as it pushes K+ from serum back into cells so can aggravate hypokalemia.
70yo F, decline in function over last few days, c/o: malaise, fatigue, weakness and confusion, O/E: puffy face, depressed reflexes and bradycardic
anaemic, high ESR, low Na+, CK is elevated, hypothermic (35.4), decreasing RR-increased C02 retention on ABG
-T4 and T3 are low and TSH are high
What is the diagnosis
Myxoedema coma
Name poss precipitating events to myxoedema coma?
- infection
- trauma
- CVA
- congestive HF
- exposure to cold
- Drugs: lithium, amiodarone, sedatives..
Along with the classic hypothyroidism features, what are the clinical features of myxoedema coma?
- hypothermia
- altered mental status e.g. coma, delusions, psychosis
- hyponatraemia: 2dry to decreased free-water clearance
- hypoglycaemia: 2dry to impaired gluconeogenesis
- hypotension
- bradycardia
- respiratory failure
Diagnosis of Myxoedema?
-clinical scenario and v. high TSH
(Have high index of suspicion
-pts w hypothroidism history
-decline in function onset is often insidious)
Name the 3 major causes of myxedma.
- undiagnosed hypothyrodism e.g. automimmune thyroiditis
- discontinuation of therapy/run out of meds over months
- iatrogenic (stopping rx for pts having I-131 scan)
What is the recommended principles In the treatment of myxoedema, how should pts be re-warmed, to avoid what? What should be monitored?
- gradually re-warm hypothermic pts w gentle passive external re-warming
- avoid hypotension from reversal of hypothermic vasoconstriction
- CVS status regularly monitored, and stabilise airway, give adequate O2 and ventilation
What are the main targets in treatment of myxoedema?
- thyroid hormone replacement (levothyroxine 300micrograms slow IV, then 100 micrograms/day)
- correct metabolic abnormalities
- identify and correct precipitating factors
- give hydrocortisone 100mg IV 8hrly
How can you correct the following abnormalities of myxoedema?
- hypoventilation:
- hyponatraemia:
- hypoglycaemia:
- hypoventilation: intubate and ventilate
- hyponatraemia: (SIADH so restrict water intake)
- hypoglycaemia: dextrose and IV fluid
Why should you avoid/be careful about giving IV thyroxine and pressors together?
Can precipitate VF/VT
so stop adrenaline/dopamine when giving IV thyroxine
Synacthen 250mcg test to diagnose hypocortisolaemia: -Omin: 130nmol/l (low) -30min: 260nmol/l (expect: 420+ rise) ACTH: high at 100ng/l dx? likely cause?
Adrenal insufficiency
Addison’s: adrenal gland doesn’t make cortisol (+/-aldosterone, HPA axis intact), what are some symptoms?
- orthostatic hypotension
- hyponatraemia
- hyperkalaemia
- mild metabolic acidosis
- hyperpigmentation of skin
Where adrenal insufficiency arise from? If adrenal gland is normal, and K+ and H+ levels normal
-dysfunction of hypothalamus/pituitary/both
Name some causes of hypoadrenalism:
- abrupt cessation of exogenous glucocorticoids (99%)
- addison’s
- secondary to pituatary disease
- tertiary from damage to hypothalamus e.g. suprasellar tumours
Name some causes of Addison’s/primary adrenal insufficiency:
- autoimmunity
- infection e.g. TB, fungal..
- haemorrhage
- metastasis
- drugs: etomidate, ketoconazole
How may adrenal failure present?Name 5 features
- weakness/fatigue
- anaorexia/weight loss
- N&V
- diziness/orthostatic syx
- hyponatramia
- hypotension, shock and death
- hyperkalaemia and hyperpigmentation in primary Addison’s
What may precipitate acute adrenal insufficiency?
- post stress (of trauma, surgery, infection, fasting) in pt w latent insufficiency
- post sudden withdrawal of adrenocortical hormone in pt w chronic insufficiency
- post bilat adrenalectomy or injury to both adrenals
- post sudden destruction of the pituitary