Approach to small animal patient with suspected Hypoadrenocorticism Flashcards
Cause of hypoadrenocorticism
Addison’s disease is commonly caused by autoimmune destruction of the adrenal cortex
Iatrogenic-Trilostane induced
Breeds predisposed to hypoadrenocorticism
Standard Poodles, Bearded Collies, Rottweilers, West Highland White Terriers
What are the effects of adrenal insufficiency in the body
Stress Response Impairment:
Cortisol is essential for the body’s response to stress. In Addison’s disease, the lack of cortisol impairs the ability to mount an appropriate stress response, making individuals more susceptible to stress-related complications.
Aldosterone Deficiency:
The adrenal cortex also produces aldosterone, a hormone that helps regulate electrolyte balance, particularly sodium and potassium, in the body. With adrenal insufficiency, there is a deficiency of aldosterone, leading to electrolyte imbalances.
Electrolyte Imbalance:
Aldosterone deficiency results in increased urinary excretion of sodium and retention of potassium. This can lead to hyponatremia (low sodium levels) and hyperkalemia (high potassium levels), causing symptoms such as weakness, fatigue, and cardiac arrhythmias.
History of patient with addisons
Chronic, vague often respond to non-specific therapy
Neurological:
Depression, weakness
Gastro-intestinal signs:
Inappetance, vomiting / diarrhoea,
Metabolic:
Failure to thrive / weight loss
Mild PU/PD
Clinical findings of Acute hypoadrenocorticism
Severe dehydration
Anorexia
Vomiting
Collapsed
Bradycardia
Haemorrhagic gastroenteritis
Complications of acute HAC
Acute renal failure
Gastro-intestinal haemorrhage
Pancreatitis
Pulmonary thromboembolism
Disseminated intravascular coagulation
What results do you expect to see from haematology test of a patient with Addisons
Anaemic
Reverse stress leucogram- Low WBC, neutropenia, lymphocytosis, eosinophilia/ Can be normal too
What results do you expect to see from biochemistry test of a patient with Addisons
Hyponatremia (Low Sodium):
Due to the deficiency of aldosterone, which normally helps retain sodium, dogs with Addison’s disease often exhibit low levels of sodium in the blood.
Hyperkalemia (High Potassium):
The lack of aldosterone also leads to impaired potassium excretion, resulting in elevated levels of potassium in the blood.
Azotemia:
An increase in blood urea nitrogen (BUN) and creatinine levels may be observed, indicating impaired kidney function.
Metabolic Acidosis:
Adrenal insufficiency can lead to a metabolic acidosis, characterized by a decreased bicarbonate concentration in the blood.
Hypoglycemia:
Low blood glucose levels may be seen, as cortisol deficiency impairs gluconeogenesis and glycogenolysis.
Suggest a cause for high K+ of a patient with hypoadrenocorticism
Aldosterone Deficiency:
In Addison’s disease, the adrenal cortex is damaged, leading to insufficient production of aldosterone. Aldosterone plays a crucial role in regulating electrolyte balance, particularly sodium and potassium, in the body.
Reduced Sodium Reabsorption:
Aldosterone normally acts on the kidneys, promoting the reabsorption of sodium and the excretion of potassium. In the absence of aldosterone, the kidneys are less effective in reabsorbing sodium.
Increased Potassium Retention:
With reduced sodium reabsorption, there is a concomitant increase in potassium retention by the kidneys. Potassium, which is normally excreted in the urine, accumulates in the bloodstream.
Consequence of hyperkalaemia
Red blood cell lysis
Failure of excretion
Others - rhabdomyolysis
Distinguishing renal failure from hypoadrenocorticism
Renal failure has stress leucogram while hypoadrenocorticism does not
Hypoadrenocorticism causes an increase in Calcium in blood
Diagnosing hypoadrenocorticism
Cortisol Definitive test
cannot distinguish primary hAC from iatrogenic HAC or recent steroid administration
Should I give dexamethasone with a patient suspected with hypoadrenocorticism
The primary diagnostic test for hypoadrenocorticism involves assessing the adrenal gland’s response to adrenocorticotropic hormone (ACTH) stimulation. Administering dexamethasone prior to this test can suppress the adrenal glands’ function, leading to inaccurate test results.
Treatment of acute Addisons
Fluid therapy
Treatment of hyperkalaemia
Saline
0.9 % saline by central venous line if possible
20 - 60 ml/kg/hr for 2 hours, then 4 ml/kg/hr
