HypO adrenocorticism Flashcards
What is CIRCI
Critical illness related corticosteroid insufficiency
> management of pressor-resistant septic shock (subset of people have relative Hypoadrenocorticism so won’t be able to protect themselves if seriously unwell)
- low dose hydrocortisone -> more rapid pressor weaning regardless of ACTH stim results (don’t need as much pressor stimulation to raise BP)
- BUT no survival benefits and ^ risk superinfections of with hydrocortisone
> doesn’t happen in vet world (we don’t think)
What is delta cortisol?
Difference between pre and post ACTH cortisol
Pathophysiology of Hypoadrenocorticism, what 2 forms exist?
> disorder resulting in clinically significant adrenocorticalysis
- immune mediated
- adrenal haemorrhage d/t ^ ACTH
reduced capacity to produce adrenocortical hormones (cortisol and aldosterone)
- typical = cortisol and aldosterone
- atypical = no electrolyte abnormalities
Which breeds are PDF Hypoadrenocorticism ?
- standard poodles (females,
2 broad clinical pictures of Hypoadrenocorticism LOOK UP
> acute
- collapse, severely compromised
- sudden onset or maybe after relapsing more subtle set of problems
- hypovolaemic and dehydrated
- shock
- may be tachycardic (hypovolaemic) or bradycardic (K+^) or neither
chronic (often presents for GI disturbance)
- subtle, unwell, waxing and waning presence
- non-specific lethargy, depression
- MELEANA (2* structural gut damage)
- VD+
-
Clin path findings with Hypoadrenocorticism
> mild mod anaemia
- non-regenerative (ill)
- regenerative (MELEANA)
hypoproteinaemia
- normoproteinemic in a hypovolaemic patient
- panhypoproteinaemia (cf. nephropathy where low weight albumen lost)
eosinophilia, lymphocytosis
- lack of stress leucogram
azotaemia and inappropriately dilute urine (d/t v Na)
hyponatraemia, hyperkalaemia, hypercalcaemia (total and ionised(not well understood))
hypoglycaemia
How does Hypoadrenocorticism affect electrolytes
- low Na
- high K
> not all cases with v Na ^ K have Hypoadrenocorticism
> Na:K ratio, look for ratio
What is seen in typical Hypoadrenocorticism
- absence of stress leuckogram
- hyponatraemia
- hyperkalaemia
What is seen with atypical Hypoadrenocorticism
- absence of stress leucogram
- normal Na and K levels
- most recently tested atypical patients also have normal aldosterone
- something about study at RVC
Why is Hypoadrenocorticism important to detect?
- Young dogs with fatal disease
- easy and cheap to Tx
> but must not start Tx without confirmed dx! - exacerbation of compromised organs
- adverse effects
- once on meds very difficult to investigate further
How much does an ACTH stim test cost?
£8
How can Hypoadrenocorticism be diagnosed
- ACTH stim best (low cortisol pre and post)
- basal cortisol necessary baseline (if above 50(?) probably not hypo)
- **ensure not receiving any form of GC iatrogenically to interfere with test results ***
Tx acute Hypoadrenocorticism
- parenterally administered medications
- IV fluids (0.9% nacl) absolutely No more than 7-8ml/kg/Hr
- adrenocortical hormone replament Tx
> short acting and GC:MC ratio equal = hydrocortisone sodium succinate
> NOT DEX (no MC activity, long t1/2, too potent)
How much is a 24hr Tx of hydrocortisone sodium succinate ?
£3 (more than dex but not expensive!)
What is Hypoadrenocorticism
- disorder resulting in marked adrenocorticolysis, often immune mediated
- > diminished adrenocortical reserve
- reduced capacity to produce cortisol and aldosterone
- may or may not be clinical significant
- a proportion of cases have NO ELECTROLYTE ABNORMALITIES = cortisol only deficiency or relative adrenocortical deficiency
What rate of hydrocortisone infusion is necessary to Tx acute Hypoadrenocorticism? Where does the GC activity come from?
0.5mg/kg/h
+ cortisol in circulation provides adequate GC and MC activity for a seriously stressed dog
Clinical signs associated with acute Hypoadrenocorticism (spontaneous cases)
- deroessed, lethargic
- dehydrated
- GI signs
- some bradycardic
- hyponatraemia
- hyperkalaemia
- hypochloremia
- azotaemia
- USG
Tx acute Hypoadrenocorticism
- IVFT (0.9% nacl 8ml/kg/hr)
- hydrocortisone sodium succinate (0.5mg/kg/hr IV, 1-2mg/ml)
> parenterally administered
> GC:MC equal activity
> short t1/2, simple, physiological and effect - oral Tx once they start eating and drinking (36hrs usually)
- reduce infusion rate to 0.25mg/kg/h IV
- stop after further 1-2days
How do Na,, K and ACTH levels change with fluid Tx of Hypoadrenocorticism
- sodium increases
- K decreased
- ACTH decreased
Tx chronic clinical picture of Hypoadrenocorticism
> Tx all body systems involved
- GIT (structural gut dz, IBD on biopsy)
- neuromuscular (weakness and lethargy)
- renal dysfunction (azotaemia, inappropriately dilute urine)
medication with appropriately balanced MC and GC activity
- fludrocortisone (mostly MC activity, GC too)
- 50% may need GC supplements (cortisone acetate if 20kg as hard to dose smaller)
- dietary considerations (salt supplementation)
- DCP (only available US, pure MC)
avoid OD with GCs
- try and use least potent GC poss (cortisone)
Correct GC dose to supplement a normal dog?
- Normal adrenal production in the dog (0.2mg/kg/day of cortisol)
- prednisolone has 5x GC activity of cortisol
- > 10kg dog needs 0.4mg per day in total!!! MUCH LOWER THAN MOST PEOPLE WILL GIVE - tablets very big.
What can excessive GC exposure cause?
- pseudomyotonia
Eg. Of an excessive GC dose for a 25kg dog
Anything over 1mg/kg
How much do cortisone acetate and hydrocortisone tablets cost?
Cortisone acetate £16/pack 30p/tablet
Hydrocortisone £60/pack £2/tablet
How can treatment efficacy be monitored?
- clinical response as overall indicator
- GC activity evaluated by leukogram (no stress leucogram wanted)
- MC activity evaluated by Na and K levels
- ACTH stim test not useful when on Tx d/t cross reaction
- basal ACTH level maybe useful(?)
What drug should be used in critical patients
Hydrocortisone
Once stable, which GC drug should be used
Cortisone acetate (esp small dogs)
