Endocrine system disorders Flashcards
Where is the pituitary gland located and what is its role?
- Sits at the base of the brain
- Connects the endocrine system to the nervous system
- Responds to the releasing of hormones secreted by the hypothalamus
What hormones do the anterior and posterior pituitary glands release?
Anterior:
- ACTH
- FSH
- GH
- LH
- Prolactin
- TSH
Posterior:
- ADH
- Oxytocin
What is hyperthyroidism?
- Overactive thyroid gland (99% of cases are caused by benign adenoma)
- Overproduction of triiodothyronine (T3) and thyroxine (T4) which increases metabolic rate
- Results in multi system disease
- Usually affects middle to old aged cats (rarely seen <10years), both male and female and all breeds (rare in pure breeds, especially siamese and himalayans)
What are some clinical signs with hyperthyroidism?
- Polyphagia with weight loss
- Palpable enlarged thyroid
- Agression/hyperactivity
- Heart murmur and tachycardia
- Hypertension
- Polyuria/polydipsia
- V+ and D+
- Blindness and retinal detachment
What diagnostics can be done for a patient with suspected hyperthyroidism?
- Blood tests (biochemistry and haematology including T4)
- Thyroid scintigraphy
What treatment and nursing care can be done for a patient with hyperthyroidism?
- Monitor vital signs
- Assist VS with diagnostic testing
- Reduce stress
- Fresh water availability
- Keep comfortable
What are the advantages and disadvantages of antithyroid drugs for hyperthyroidism?
Advantages:
- Routinely available
- Reversible
- Spreads the cost
Disadvantages:
- Not curative
- Daily administration
- Drug side effects
What are the advantages and disadvantages of antithyroid drugs for hyperthyroidism?
Advantages:
- Routinely available
- Reversible
- Spreads the cost
Disadvantages:
- Not a cure
- Daily administration needed
- Drug side effects
What are the advantages and disadvantages of limited-iodine food for hyperthyroidism?
Advantages:
- Routinely available
- Reversible
- Spreads the cost
Disadvantages:
- Not curative
- Cat can only eat a single food
What are the advantages and disadvantages of limited-iodine food for hyperthyroidism?
Advantages:
- Routinely available
- Reversible
- Spreads the cost
Disadvantages:
- Not a cure
- Cat can only eat a single food
What are the advantages and disadvantages of radioactive iodine for hyperthyroidism?
Advantages:
- Cures current tumour
- Single treatment
- Effective for ectopic tissue
- Side effects uncommon
Disadvantages:
- High initial costs
- Limited availability
- Hospitalisation required
- Irreversible (may negatively affect renal function in cats with kidney disease)
What are the advantages and disadvantages of thyroidectomy for hyperthyroidism?
Advantages:
-Cure current tumour
Disadvantages:
- High initial cost
- Requires anaesthesia and hospitalisation
- Risk of postoperative hypocalaemia
- Irreversible (may negatively affect renal function in cats with kidney disease)
What is hypothyroidism?
- Underactive thyroid gland
- Most commonly caused by auto-immune destruction of the thyroid gland
- Results in decreased production of thyroxine (T4) and metabolic rate
What are some clinical signs that may be seen with hypothyroidism?
- Lethargy/exercise intolerance
- Obesity
- Bradycardia
- Dermatological abnormalities (alopecia, pyoderma, hyperpigmentation)
What diagnostics can be done for a patient with suspected hypothyroidism?
- Blood tests (biochemistry and haematology)
- Total T4 and thyroid stimulating hormone (TSH) assay
What treatment and nursing care can be done for a patient with hypothyroidism?
- Monitor vital signs
- Assist VS with diagnostic tests
- Fresh water available
- Keep comfortable
- Medication under VS direction (lifetime supplementation of thyroxine)
- Suitable diet
Where are the adrenal glands located and what hormones do they produce?
- Located dorsally and cranially to the kidneys
- Two distinct areas each producing own set of hormones:
1. Adrenal medulla = Adrenaline and noradrenaline (fight/flight response), controlled by sympathetic nervous system
2. Adrenal cortex = glucocorticoids (eg cortisol), mineralocorticoids (eg aldosterone - regulates electrolytes and water), sex hormones
What is pituitary dependent hyperadrenocorticism?
- Oversecretion of ACTH by pituitary gland (most likely due to tumour)
- ACTH is hormone that stimulates the adrenal gland to produce glucocorticoids
- Responsible for around 80% of canine Cushings cases
- Compression of the base of the brain ad optic nerves
What is adrenal-based hyperadrenocorticism?
- Adrenal tumour causes over secretion of cortisol
- Responsible for around 20% of canine Cushings cases
What is Iatrogenic Cushings?
- Result of giving animal high dose of steroids
- Cushings symptoms will go once steroids have stopped
What are some clinical signs of Cushings?
- Polyuria/polydipsia
- Polyphagia
- Potbelly
- Panting
- Bilateral alopecia and skin changes (thin elastic skin)
- Skin and other infections
- Muscle atrophy and weakness
- Neurological signs
What diagnostics can be done for a patient with suspected Cushings?
- Abdominal ultrasound and X-ray
- MRI or CT
- General blood tests
- Specific blood tests
What specific tests can be done for suspected canine Cushings?
- ACTH stimulation = determines if adrenal glands are releasing too much cortisol
- Low-dose Dexamethasone Suppression Test (LDDST) = decreases amount of ACTH released by pituitary gland decreasing amount of cortisol by adrenals, high levels of cortisol post injection suggest Cushings
- High-dose Dexamethasone Suppression Test (HDDST) = Distinguishes between pituitary and non-pituitary dependent Cushings; low levels of cortisol post injections suggest pituitary dependent, high levels of cortisol post injection suggest non-pituitary dependent
- Serum insulin levels = high levels suggest Cushings due to cortisol causing insulin resistance
What treatment and nursing care can be done for a patient with Cushing’s?
- Careful handling (haematomas/bruising common)
- Fresh water available
- Frequent toileting
- Pituitary dependent HAC treated medically
- Adrenal dependent HAC treated medically or surgically
- Oral medication (trilostane most common for dogs)
What is hypoadrenocortisim (Addisons disease)?
- Atrophy of adrenal cortex resulting in decreased production of glucocorticoids and mineralocorticoids
- Most commonly caused by auto-immune destruction of adrenal gland
What does a lack of cortisol and aldosterone cause?
Cortisol:
- Weakness
- V+
- Anorexia
Aldosterone:
- Hyponatramia (low sodium)
- Hyperkalaemia (high potassium)
What are some clinical signs that may be present with Addisons disease?
- May be vague
- Lethargy/depression
- Anorexia/weight loss
- V+ and D+
- PU/PD
- Coat changes
- May present in Addisonian crisis (arrhythmias eg bradycardia caused by hyperkalaemia, severe hypovolaemia, pre renal azotaemia, collapse)
What diagnostics can be done for a patient with suspected Addisons disease?
- Blood tests (haematology and biochemistry: low sodium, high potassium)
- ACTH stimulation test
- ECG
What treatment and nursing care can be done for a patient with Addisons disease?
- IVFT (usually 0.9% saline to treat hyponatraemia, shock doses in crisis)
- Monitor vital signs (especially hydration)
- Medication under VS direction (hydrocortisone or dexamethasone IV every 6 hours in crisis, dextrose and insulins to increase uptake of potassium by cells, Zycortal injection once monthly SC)
- Stimulate appetite
- Fresh water available
- Frequent toileting (monitor urine output)
- ECG
What hormones do the Alpha, Beta and Delta cells release in the Islets of Langerhans in the pancreas and when are they stimulated?
Alpha = produce glucagon, stimulated by low glucose concentration or stress Beta = produce insulin, stimulated by high glucose levels Delta = produce somatostatin, regulatory role inhibiting the release of both glucagon and insulin
Outline diabetes mellitus in cats
- Diabetes Mellitus II
- Insulin resistance due to obesity
- Reversible if treated quickly enough
- Result in hyperglycaemia
- Eventually patients breakdown fat store resulting in raised ketone levels
Outline diabetes mellitus in dogs
- Diabetes Mellitus I:
- Insulin deficiency
- Auto-immune destruction of beta cells of the pancreas
- Irreversible but with appropriate control can live a healthy and normal life
Diabetes Mellitus II:
- Insulin resistance
- Resistance caused by obesity
Both:
- Result in hyperglycaemia
- Eventually patients breakdown fat store resulting in raised ketone levels
What are some clinical signs of diabetes mellitus?
- Polyuria/polydipsia
- Polyphagia with weight loss
- Plantigrade posture in cats
- Cataracts
- Urinary tract infections
- Hypertension
- Glaucoma
- DKA (serious) -> V+, D+, anorexia, collapse, acetone breath
What diagnostics can be done for a patient with suspected diabetes mellitus?
- Bloods (haematology, biochemistry and fructosamine levels)
- Urinalysis
What treatment and nursing care can be done for a patient with diabetes mellitus?
- Client/outpatient support
- Fresh water availability
- Patients with type 2 diabetes may enter remission from diet and exercise alone
- Insulin administration under direction (SID vs BID)
- Glucose curves in and out of practice
- Monitor blood glucose levels at home
- Low carb diet (strict times if on insulin)
- Patients on insulin require strict exercise routine
What support can be given from an inpatient with DKA (diabetic ketoacidosis)?
- Monitor blood glucose and electrolyte levels
- Supplement IVFT as required
- Stimulate appetite
- IV glucose/insulin under VS direction
What clinical signs may be present with insulin overdose?
Causes hypoglycaemia
- Altered mentation
- Syncope and weakness
- Tremors and seizures
- Collapse
What is diabetes insipitus (DI)?
-ADH usually released in the pituitary gland and acts on the distal convoluted tubule to retain water
-Large volume of dilute urine produced
-“Water diabetes”
TWO FORMS:
-Central DI = decrease in ADH produced by the pituitary
-Nephrogenic DI = collecting tubules in the nephrons fail to respond to ADH
What are some clinical signs associated with diabetes insipitus?
- PU/PD
- V+ (after drinking ++)
- Weight loss (poor appetite due to constant thirst)
What diagnostics can be done for a patient with suspected diabetes insipitus?
- Haematology and biochemistry (both usually normal)
- Urinalysis (SG <1.009)
- Water deprivation test
- Trial of ADH
Explain how to perform a water deprivation test
NOTE: patient should be well hydrated, have normal blood urea level and be closely monitored throughout procedure
- Empty the bladder and measure SG
- Weigh animal and calculate 5% of its BW
- Put away with no access to food or water
- Empty bladder every hour, check SG and weigh the animal
- Once 5% of the BW has been lost stop the test
- Normal result: SG >1.025, if SG <1.020 suspect DI
Once rehydrated, repeat but give ADH injections or drops
- If increased SG = central DI
- No change in SG = nephrogenic DI
What treatment can be given for central and nephrogenic DI?
Central DI:
-Desmopressin acetate (DDAVP) nassal/eye drops = synthetic ADH
Nephrogenic DI:
-Chlorothiazide diuretics (hydrosaluric)
What nursing care can be done for a patient with DI?
- Monitor hydration status
- Assisting with diagnostics
- Fresh water available (unless performing deprivation test)
- Frequent toileting
- Administer medication under VS direction
