Cushings/Addisons Flashcards
What does the cortex of the adrenal gland do
Produces the glucocorticoid cortisol and aldosterone
What does the cortex of the adrenal gland do
Produces the glucocorticoid cortisol and aldosterone
What does the medulla of the adrenal gland do
Secretes as epinephrine or adrenaline
What is the function of aldosterone
Aldosterone acts on renal tubes to preserve and reabsorb Sodium and excrete Potassium
What are the 3 types of cushion’s disease
- Pituitary tumor
- Adrenal gland tumor
- Iatrogenic
Why does a pituitary tumor cause cushings disease
Pituitary tumor (adenoma) produces excess ACTH overstimulates the adrenal gland xs cortisol
What does the hypothalamus produce
Corticotropin releasing factor
What does the corticotropin releasing factor do to the pituitary gland
Causes the pituitary to release ACTH.
What is ACTH
Adrenocorticotropic hormone
What does ACTH do in the body
Causes adrenal growth and secretion.
What does the adrenal gland produce
Cortisol (glucocorticoid)
What effect does cortisol have on the body
Inhibits CRF and ACTH by means of negative feedback
What are the hormones released by the Anterior pituitary gland
Thyroid, adrenal, ovary, teste
What are the hormone released by Posterior pituitary
Oxytocin, vasopressin (ADH)
What does a brain or pituitary tumor do
Causes excess ACTH –> Secondary bilateral adrenal hyperplasia –> excess cortisol
What does the adrenal gland tumor do
Other adrenal will become hypoplastic and unilateral,
What are the 3 types of excess cortisol hyperadrenocorticism
- Brain or pituitary tumor
- Adrenal gland tumor
- Iactrogenic
Describe pituitary dependant cushings disease
Up to 90% of all Cushing’s cases in dogs fall into this category.
It is slow growing cancer called an adenoma ( pituitary).
This causes secretion of excess ACTH.
The adrenal glands respond to this excess ACTH by enlarging and secreting excess cortisol.
Describe non-pituitary dependent cushings disease
In up to 15% of Cushing’s there is an actual tumor of one of the adrenal glands (sometimes both are involved). It enlarges and secretes excess cortisol in the bloodstream.
The benign version of this tumor occurs 50% of the time, and is called an adenoma.
The malignant version, which occurs the other 50% or the time, is called an adenocarcinoma. It can spread from the adrenal gland to the liver, lung, kidney, and lymph nodes.
Describe iatrogenic cushings disease
Long term use of supplemental cortisone, in oral, injectable, or even topical form, might cause an animal to have the symptoms of Cushing’s disease.
i.e. Long term use of Drug prednisone. will cause the adrenal glands to shrink in size. This is because the negative feedback loop tells the brain there is plenty of cortisol in the bloodstream, so the pituitary secretes less ACTH.
What does Iatrogenic hyperadrenocorticism
exogenous excess cortisone atrophied adrenal glands
Sudden withdrawal results in Addisonian crisis
What are the clinical signs of cushings disease
Polyphagia- excess appetite.
Polyuria/polydypsia (PU/PD)-
Pot bellied abdomen.
Thin skin and usually symmetrical hair loss along the trunk. The hair might grow in lighter in color or even be hyperpigmented. Secondary skin infections are common.
Other symptoms could include lethargy, muscle wasting, poor appetite, weakness, and behavioral changes.
Describe the signalment of cushings diease
Cushing’s tends to be a problem that affects older dogs, usually greater than 10 years of age. The disease tends to have a slow and gradual onset, so the early symptoms are easily missed.
What are the breed dispositions of cushings disease
Yorkshire Terrier Poodle Beagle Boston Terrier Boxer Dachshund
How do you diagnose cushings
CBC might show an increased WBC and an eosinopenia ( cortisol)
BIOCHEM
****elevated alkaline phosphatase (Alk Phos) **
maybe elevation Cholesterol
Urinalysis
Low sp .gravity often
What does the urine cortisol/creatinine ratio show
is a screening test for Cushing’s disease;
a positive test here does NOT confirm Cushing’s syndrome but a negative test DOES rule it out.
If there is a high ratio - a relatively high amount of cortisol being excreted - further testing is in order.
Ideally for this test the urine sample is collected at home so that cortisol secreted in response to the stress of visiting the vet’s office does not interfere with results.
Specific diagnostic tests for cushings
ACTH Stimulation test
Low Dose Dexamethasone Suppression Test (LDDS)
High Dose Dexamethasone Suppression Test (HDDS)
How do you treat a pituitary tumor
give drugs that will partially destroy or prevent the adreanal gland from secreting excess cortisone
Mitotane (o,p’-DDD) Lysodren,
L-Deprenyl (anipryl)
Ketaconazole
How do you treat an adrenal tumor
can do surgery or use above drugs
What is Hypoadrenocorticism or Addison’s dse
Cortisone and a mineralocorticoid deficiency (aldosterone)
Atrophy of adrenal cortex
Results in decrease of glucocorticoids (cortisone) and mineralocorticoids (aldosterone)
What are the clinical signs of addison disease
What are the clinical signs of addison disease
What does the medulla of the adrenal gland do
Secretes as epinephrine or adrenaline
What is the function of aldosterone
Aldosterone acts on renal tubes to preserve and reabsorb Sodium and excrete Potassium
What are the 3 types of cushion’s disease
- Pituitary tumor
- Adrenal gland tumor
- Iatrogenic
Why does a pituitary tumor cause cushings disease
Pituitary tumor (adenoma) produces excess ACTH overstimulates the adrenal gland xs cortisol
What does the hypothalamus produce
Corticotropin releasing factor
What does the corticotropin releasing factor do to the pituitary gland
Causes the pituitary to release ACTH.
What is ACTH
Adrenocorticotropic hormone
What does ACTH do in the body
Causes adrenal growth and secretion.
What does the adrenal gland produce
Cortisol (glucocorticoid)
What effect does cortisol have on the body
Inhibits CRF and ACTH by means of negative feedback
What are the hormones released by the Anterior pituitary gland
Thyroid, adrenal, ovary, teste
What are the hormone released by Posterior pituitary
Oxytocin, vasopressin (ADH)
What does a brain or pituitary tumor do
Causes excess ACTH –> Secondary bilateral adrenal hyperplasia –> excess cortisol
What does the adrenal gland tumor do
Other adrenal will become hypoplastic and unilateral,
What are the 3 types of excess cortisol hyperadrenocorticism
- Brain or pituitary tumor
- Adrenal gland tumor
- Iactrogenic
Describe pituitary dependant cushings disease
Up to 90% of all Cushing’s cases in dogs fall into this category.
It is slow growing cancer called an adenoma ( pituitary).
This causes secretion of excess ACTH.
The adrenal glands respond to this excess ACTH by enlarging and secreting excess cortisol.
Describe non-pituitary dependent cushings disease
In up to 15% of Cushing’s there is an actual tumor of one of the adrenal glands (sometimes both are involved). It enlarges and secretes excess cortisol in the bloodstream.
The benign version of this tumor occurs 50% of the time, and is called an adenoma.
The malignant version, which occurs the other 50% or the time, is called an adenocarcinoma. It can spread from the adrenal gland to the liver, lung, kidney, and lymph nodes.
Describe iatrogenic cushings disease
Long term use of supplemental cortisone, in oral, injectable, or even topical form, might cause an animal to have the symptoms of Cushing’s disease.
i.e. Long term use of Drug prednisone. will cause the adrenal glands to shrink in size. This is because the negative feedback loop tells the brain there is plenty of cortisol in the bloodstream, so the pituitary secretes less ACTH.
What does hypothyroidism do
inadequate active thyroid hormone
most common hormone imbalance of the dog.
In Dogs:
T3 is the active form
T4 is the inactive form
When T4 is absorbed into tissue cells, it is converted into T3
What are the clinical signs of cushings disease
Polyphagia- excess appetite.
Polyuria/polydypsia (PU/PD)-
Pot bellied abdomen.
Thin skin and usually symmetrical hair loss along the trunk. The hair might grow in lighter in color or even be hyperpigmented. Secondary skin infections are common.
Other symptoms could include lethargy, muscle wasting, poor appetite, weakness, and behavioral changes.
Describe the signalment of cushings diease
Cushing’s tends to be a problem that affects older dogs, usually greater than 10 years of age. The disease tends to have a slow and gradual onset, so the early symptoms are easily missed.
What are the breed dispositions of cushings disease
Yorkshire Terrier Poodle Beagle Boston Terrier Boxer Dachshund
How do you diagnose cushings
CBC might show an increased WBC and an eosinopenia ( cortisol)
BIOCHEM
****elevated alkaline phosphatase (Alk Phos) **
maybe elevation Cholesterol
Urinalysis
Low sp .gravity often
What does the urine cortisol/creatinine ratio show
is a screening test for Cushing’s disease;
a positive test here does NOT confirm Cushing’s syndrome but a negative test DOES rule it out.
If there is a high ratio - a relatively high amount of cortisol being excreted - further testing is in order.
Ideally for this test the urine sample is collected at home so that cortisol secreted in response to the stress of visiting the vet’s office does not interfere with results.
Specific diagnostic tests for cushings
ACTH Stimulation test
Low Dose Dexamethasone Suppression Test (LDDS)
High Dose Dexamethasone Suppression Test (HDDS)
How do you treat a pituitary tumor
give drugs that will partially destroy or prevent the adreanal gland from secreting excess cortisone
Mitotane (o,p’-DDD) Lysodren,
L-Deprenyl (anipryl)
Ketaconazole
How do you treat an adrenal tumor
can do surgery or use above drugs
What is Hypoadrenocorticism or Addison’s dse
Cortisone and a mineralocorticoid deficiency (aldosterone)
Atrophy of adrenal cortex
Results in decrease of glucocorticoids (cortisone) and mineralocorticoids (aldosterone)
What is the free T4
Most of the circulating T4 is carried by blood proteins and is not available for tissue absorption;
the portion that is not carried by proteins (the so-called “free T4”)
free T4 is the portion that is able to enter tissues for activation
What are the clinical signs of addison disease
What is an addison crisis
Medical Emergency—
Presents with sudden weakness, vomiting, diarrhea
Low Na- causes a drastic drop in Blood pressure
High K - heart problems
Hypovolumemic – symptoms of shock
How do you treat an addison crisis
Crisis- fluids– Normal Saline Replace Na (do not want K)
Cortisone- prednisone or dexamethasone
What is the treatment for addisons
Percoten V - monthly injections,
Florinef- tablets
How do you diagnose addison disease
Pre treatment Blood work: electrolyte imbalance
Na:K – less than 27:1
Often pre renal increase in BUN CREAT
High BUN in absence of Kidney dse
How do you confirm the diagnosis of addison disease
ACTH stimulation test to confirm addisons
What is an ACTH sim test used for
used To dx Addison’s or Cushing’s
Evaluates the degree of adrenal response to exogenous ACTH
What hyperplastic adrenal gland do
Exaggerated response indicates cushings
What does a hypo plastic adrenal gland do
Diminished response indicates addisons
What is Low dose dexamethasone Suppression test
Replaces the ACTH test - to diagnose cushings
What is High dose Dex. Suppression test
helps to distinguish if it’s a pituitary or adrenal tumor
What dexamethasone suppression test is used for cats
use only in the high dose test
What is the LDDST Protocol
Patient fasted before collection.
i) Collect blood into a plain or SST for a baseline cortisol
ii) Administer 0.01 mg/kg off dexamethasone IV
iii) Collect post-dexamethasone blood into a plain or SST at both 4 hours and 8 hours post-dexamethasone administration
What are the results of LDDST
In the normal animal blood cortisol level will drop after a tiny dose of dexamethasone is given
If there is a pituitary tumor, it will not turn off its stimulatory message and it ignores the dexamethasone. There is No drop in cortisol level is seen at the end of eight hours
Adrenal tumor will not suppress either
How does the low dose/high dose work
Normally dexamethasone suppress ACTH decreased cortisol
Pituitary tumor does not suppress to a low dose dex, but will suppress to a high dose dex– ( results in lower cortisol levels)
Adrenal gland tumor pumps out cortisol regardless of ACTH NO Suppression by large dose dex
High dose dex suppression test will distinguish between the adrenal and pituitary cause of cushing’s
Why can’t we measure ACTH
Very labile protein– requires special handling for sample—and immediate freezing of the plasma
What does a pituitary tumor cause
HIGH ACTH
What does an adrenal tumor
LOW ACTH
What does the thyroid gland produces
T4 Thyroxine
T3 Tri-iodothyronine
What do T3 and T4
These hormones regulate metabolism of all tissues and organs
What does hypothyroidism do
inadequate active thyroid hormone
most common hormone imbalance of the dog.
In Dogs:
T3 is the active form
T4 is the inactive form
When T4 is absorbed into tissue cells, it is converted into T3
What causes hypothyroidism
immune-mediated destruction of the thyroid gland,
natural atrophy of the gland,
dietary iodine deficiency, (Goiter)
a congenital problem
What are the breeds predisposed to hypothyroidism
the Doberman pinscher, the Golden retriever, the Irish Setter, the Great Dane, the Dachshund, the Boxer
What are the clinical signs of hypothyroidism
Weight gain without an increase in appetite
Lethargy and lack of desire to exercise
Cold intolerance (gets cold easily)
Dry, dull hair with excessive shedding and flaking
Very thin to nearly bald hair coat
Increased dark pigmentation in the skin
Increased susceptibility and occurrence of skin and ear infections
Failure to re-grow hair after clipping or shaving
High blood cholesterol
Slow heart rate
What is hypothyroidism
biochemistry panel might show an elevated cholesterol ( 75% of time)
CBC mild non responsive anemia
May see target cells due to cholesterol deposits on RBC membrane
What is the physiology of hypothyroidism
(Hypothalmus) TRF pituitary (TSH) - thyroid gland T3 +T4 (triiodothyronine and thyroxine)
All of the T4 is produced by thyroid
T4 can be converted to converted to T3 at the tissue level
Most T4 + T3 in blood is protein bound
fT4 freeT4 enters the cell and is converted to T3
Describe the Pituitary gland
pituitary gland –. TSH
When T4 levels are dropping, the pituitary gland sends out TSH–stimulates the thyroid gland to make and release more T4.
You expect to have a high TSH in a hypothyroid dog
What is the total T4 screening test
Often part of a geriatric profile
What is the free T4 by equilibrium dialysis
Can be a more specific test
Do we ever do TSH and T4 together
Yes
What is the free T4
Most of the circulating T4 is carried by blood proteins and is not available for tissue absorption;
the portion that is not carried by proteins (the so-called “free T4”)
free T4 is the portion that is able to enter tissues for activation
What is Euthyroid sick
Many chronic illnesses will cause an animal to have a low T4 and he is not hypothyroid
What is the TSH response test
Many diseases and drugs can suppress T4 levels– this test is more sensitive
How do you do the TSH response test
Draw Pre-test blood sample
– give TSH
Draw post-test blood samples 4-6 hrs later
Normal dogs or euthryoid sick dogs should show increased T4
Hypothyroid dog shows no increase
What are the two other hypothyroid tests
TRH- thyrotropin –Releasing Hormone Response test
Triiodothyronine Suppression test
Monitoring thyroid treatment
Monitoring with T4
Monitoring with +/- TSH level
How do you know if diagnosis correct
to repeat test:
thyroid hormone supplementation must be discontinued at least 2 months for blood testing to be valid
What is hyperthyroidism
Caused by benign tumor (adenoma) on the thyroid gland excess of amounts of T3 and T4.
These adenomas are not under the control of TSH
What are the clinical signs of hyperthyroidism
Weight loss Excess appetite (polyphagia) Decreased appetite (anorexia) Nervousness , vocalization Muscle weakness Vomiting (emesis) Diarrhea Excess drinking and urinating (polyuria and polydipsia) Poor hair coat High heart rate (tachycardia) ( 200-300bpm) - gallop rhythm Labored breathing (dyspnea)
What are the secondary complications of hyperthyroidism
thyrotoxic cardiomyopathy
Hypertension (high blood pressure)
If left untreated there are significant complications that can develop. Blindness can occur due to retinal detachment from high blood pressure.
Long term kidney damage and non-stop diarrhea might also be consequences, along with heart failure and death.
What are the elevated enzymes in a biochem panel
Elevated liver enzymes on biochem panel- ALT AST
How do you diagnose hyperthyroidism
Routine geriatric biochemistry
Total T4 is very elevated
Sometimes if T4 is normal and Hyperthyroidism is suspected the free T4 by equilibrium dialysis will be done
What are the 4 treatment hyperthyroidism
Radioactive Iodine
Tapazole (Methimazole) - monitor T4 levels
Surgery (thyroidectomy)
Y/D diet from Hills ( has no iodine)- monitor T4 levels
