Endocrine disorders - The Adrenal Gland: Hypoadrenocorticism 'Addisons'

Addison’s disease (HOC) - Reduced activity of the adrenal glands

• Glucocorticoids

• Mineralocorticoids - electrolyte balance

• Adrenal sex hormones

• Dogs > cats & Females > males

Addison’s disease (HOC) - Primary

Reduced adrenal production of all hormones

Addison’s disease (HOC) - Atypical primary

• Reduced production of glucocorticoids but normal electrolytes

• Mineralocorticoids can be sufficient, insufficient or deficient

Addison’s disease (HOC) - Secondary

Reduced ACTH secretion

Addison’s disease (HOC) - Iatrogenic

• Decreased due to exogenous steroid therapy (adrenal atrophy)

• Activating the negative feedback loop by giving steroid - once steroids given then ‘iatrogenic’ can be caused

Clinical signs of 1st degree HOC - Chronic

• Anorexia

• Lethargy

• Weakness

• Vomiting

• Diarrhoea

• Polydipsia/polyuria

• Hypotension

• Bradycardia

Clinical signs of 1st degree HOC - Acute (addisonian crisis)

• Medical emergency

• Hypovolaemic shock

• Hypotension

• Collapse

• Severe bradycardia

• Vomiting

• Diarrhoea

Diagnosis of 1st degree HOC - Haematology

Lack of stress leucogram

Diagnosis of 1st degree HOC - Biochemistry

• Low sodium (hyponatremia)

• Elevated potassium (hypokalaemia)

• ^Na:K (<25:1) - indicative

• Azotaemia

Diagnosis of 1st degree HOC - ACTH stimulation test

Little or no increase in blood cortisol in response to exogenous ACTH

ACTH stimulation test - HOC

Low cortisol at the start, and low cortisol an hour later

ATCH stimulation test - HOC - process

1. Fasted blood sample for baseline cortisol

2. Inject synthetic ACTH IV

3. Repeat cortisol blood sample 1hr later

Treatment of acute HOC

‘Addisonian crisis’

• Intravenous fluid therapy

• Glucocorticoids

• +/- dextrose (if hypoglycaemic)

• +/- sodium bicarbonate (if acidotic - care! - if correct in one direction and over-do it, it can be pushed in the other direction)

Treatment of acute HOC - Glucocorticoids

• Methylprednisolone or dexamethasone IV

• Hydrocortisone has both glucocorticoids and mineralocorticoid activity

Nursing care of the acute HOC patient

• Likely to be recumbent initially

• Monitor vital signs and clinical signs

• Assist with diagnostic tests

• IVFT

• Administration of medication

Treatment of chronic 1st degree HOC - Mineralocorticoid

• Deoxycorticosterone pivalate (Zycortal)

• Subcutaneous injection

• Approx 25days

• Regular monitoring

Treatment of chronic 1st degree HOC - Glucocorticoid

• Prednisolone (low dose)

• Increase at times of stress/pre-surgery

Desoxycortone

• A corticosteroid with predominantly mineralocorticoid action

• Replaced the mineralocorticoid (aldosterone) = agonist

Desoxycortone - pharmacy

• Administered by subcutaneous injection

• Induvial variation in response with dosing interval between 20-46 days during licensing

Prednisolone

Acts like cortisol / glucocorticoid = agonist

Prednisolone - pharmacy

• Variety of formulation available

• generally administered in tablet form for this condition - range of tablet sizes allows for individual dose to the filtrated to suit need

• 80% bioavailability when administered orally

• Highly plasma protein bound

Nursing care of the chronic HOC patient - if hospitalised

• Reduce stress

• Anaesthetic risk - often increase dose of glucocorticoids

• Toileting (PU)

• Water intake (PD)

• Monitor closely - risk to acute-on-chronic

Nursing care of the chronic HOC patient - once home

• Owner support

• Long-term treatment

• Regular checks

• Clinical signs of deterioration

• Assess with regular diagnostic tests