Adrenal Gland Endocrinopathies Flashcards
What hormones does the different parts of the adrenal gland produce
Medulla: catecholamines Cortex: Z. Reticularis (inner) - GC Z. Fasciculata - androgens Z. Glomerulosa (outer) - mineralocorticoids (aldosterone fex)
How is cortisol stimulated and inhibited
(Part of day feeding?)
Stress ➡️ CRH ➡️ ACTH ➡️ cortisol/corticosterone
- AVP/ADH/vasopressin, angiotensin II also influence ACTH production
The cortisol in the blood acts as negative feedback for all steps.
What stimulates the RAAS
Renin angiotensin aldosterone system - activated as a reaction to hypovolemia.
Hypovolemia ➡️ renin ➡️ ang 1 >2 ➡️ aldosterone ➡️ ⬆️Na, ⬇️K
- incr. K will also stimulate aldosterone production
- ACTH will minimally stimulate aldosterone
What is Hypoadrenocorticisom
Aka addisons disease, lack of adrenocortical hormones (sickness of the adrenal cortex)
Pathogenesis of addisons disease
🔺 Primary (if 90% of AC tissue is lost)
– Cortisol ⬇️ and aldosterone ⬇️, ACTH⬆️
– Autoimmune destruction of cortex (➡️ atrophy)
– (bilateral adrenal tumor, amyloidosis, infection) –„Atypical”: only cortisol⬇️ (yet, ald maybe later)
🔺 Secondary
– ACTH ⬇️, cortisol ⬇️, aldosterone no problem!
–Unprofessional glucocorticoid therapy
– (Hypophysis tumor, trauma, inflammation)
What is the major cause of primary addisons
Autoimmune distrustion of cortex (lymphocytic adrenalitis and atrophy of AC)
Signalment of addisons
~ Rare, but life threatening disease of dogs (but lethal - important ddx)
~ Young and middle-aged animals
~ More frequent in bitches
~ Great Dane, Rottweiler, Poodle, Schnauzer, Westie, Bearded collie, English cocker spaniel (hu!!)
~ (Very rare in cats)
What are the clinical manifestations of addisons
🔺
Aldosterone ⬇️
➡️ Dehydration, K⬆️
➡️ Addisonian-crisis Cortisol⬇️
➡️ Lethargy, stress response⬇️
🔺 Periodic improvement and relapse
🔺 Stress might cause a crisis
🔺 cortical deficiancy: Depression, weakness, tremor, weight loss, hypothermia, anorexia
🔺 Vomiting/diarrhea (+/- bloody), abdominal pain, PD/PU
🔺 hypovol. shock, CRT⬆️, bradycardia, weak pulse (Addisonion crisis!! The bradycardia indicates it - normal adrenal would react with incr hr! Or maybe bad heart could be)
🔺 When these signs are present, include Addison’s disease in differential diagnosis !
Lab and instrumental findings in addisons
~ Normocytic normochromic anemia (dehydration can mask the anemia!)
~ Lack of „stress leukogram”: Neu/Ly <2,3 eosinophilia, lymphocytosis (Corticol overprod -> leukocytosis with mature neutrophilia = stress leukogram (addison patients cant cause this ever!!) doesnt atter how sick)
~ Hyponatremia(water follow), hyperkalemia(should! activate RAAS), hypochloremia
Na /K <27(<22) (These should be present in typical addisons simultaniously)
~ (Hypoglycemia), albumin ⬇️(vomitus, diarrhoea), prerenal azotemia (Severily hypovol + addisonial crisis –> decr bp -> prerenal azotemia)
~ ECG (incr K): spiked T wave, Q-T distance ⬆️,
QRS complex wide, P wave low, P-R distance ⬆️, bradycardia
~ X-ray: microcardia, v. cava caudalis ⬇️ (connected to hypovol)
~ Abdominal US: „thinner” adrenals if examiner is experienced
Addisons ddx
– Renal failure (Na/K may be low)
– Gastroenteritis (Na/K may be low eg if vomitus dominating)
– Acute pancreatitis, (Ileus)
Addisons diagnostics
🔺 ACTH-stimulation test
– 5 μg/kg tetracosactide IV (Synacthen inj.)
– Blood sampling: t0, t1
– Positive: t0 cortisol <28nmol/l, t1 cortisol <100 nmol/l
– On the morning of the test the hydrocortisone injection should be postponed (it would incr cortisone)
🔺 Single cortisol >55 nmol/l: Addison’s unlikely (if a single measurement is above this we can rule out - if not need acth stim test!) this is good to try first esp if cant get hold of tetracosactide
Treatment - give an overview
2 phases: first stabilise the addisonian crisis then maintenance therapy
How would you treat the addisonian crisis?
Hypovolemia + hormone repl. Treatment!
– 20-50 ml/kg/h normal saline for 2 hours (0.9%saline, no K so dilutes hyperkal!)
– Thereafter: 100 ml/kg/24h normal saline
– 5 mg/kg hydrocortisone with the first infusion (Solu-Cortef inj.)
– Thereafter: 1 mg/kg/6h hydrocortisone SC
Should feel better after some days (no vomitus, diarrh, hypovol, incr appatite)
Why is hydrocortisone preferred in stabilizing the addisonian crisis?
An “old” GC, has mineralocorticoid effect too - aldosterone effect aswell as incr cortisol.
–> help hypovolemia aswell (Na⬆️K⬇️)
How would you treat the patient after stabilizing the addisonian crisis?
Maintenance therapy - long term treatment!
➡️ we treat lacking GC+MC!
– Fludrocortisone (tablet BID, Mineralocorticoid, some GC activity aswell!)
or
DOCP IM/SC (Desoxycorticosterone-pivalate) Long acting inj., lasting 25-28d. Strictly mineralocort so we prescribe together with prednisolone aswell. Life long treamtent.
– Prednisolone (tabl BID.; in stress 2-4x dose!)
– Sodium chloride BID mixed with food (hyponatremia)