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What are the different endocrine glands in the body?
- hypophysis (pituitary gland)
- thyroid gland
- parathyroid gland
- adrenal gland
What do endocrine glands do?
- produce hormones
- transported by blood
- affect target organs
What are diseases related to?
under or over production of hormones
What are the different diseases seen with endocrine glands?
- diabetes mellitus
- diabetes insipidus
- islet cell tumor (insulinoma)
What does congenital mean?
born with it but its not necessarily genetic
What does hypopituarism cause?
dwarfism and may see hypothyroidism
Is hypopituarism common?
What is the difference of an animal who is a runt verses an animal with hypopituarism?
- the runt is smaller due to not getting enough nutrients and will eventually catch up with the others
- an animal with hypopitarism will always be smaller
What hormones do the thyroid glands produce?
T3 and T4
What does the thyroid glands do?
stimulates cellular metabolism and goes to tissues throughout the body
What does euthyroid mean?
means normal thyroid gland
Can you have low thyroid levels and a normal thyroid gland?
Is hypothyroidism common in dogs?
Is hypothyroidism common in cats?
not as common as in dogs
Is hypothyroidism easy to diagnose?
What are the signs of hypothyroidism?
- bilaterally symmetrical alopecia
- recurrent pyoderma skin problems
- recurrent otitis externa (ear problems)
- cold intolerance
- peripheral neuropathy
What will we often see on blood tests with hypothyroidism?
- mild nonregenerative anemia
- elevated triglycerides
What can affect thyroid testing (causes hormone levels to go up and down)?
- reproductive state
- serum proteins
- drug therapies
- body size
Do we need to use several tests when testing for hypothyroidism?
yes, no one test is definitive
What in house tests can be done to test total T4?
- CITE Semi-Quant T4
- Snap T4
- VetTest reader
Total T4 may be _____ if hypothyroid and may be _____ when euthyroid.
What drugs could potentially lower T4?
- potentiated sufonamides
- furosemide (Lasix)
- radiocontrast agents
If an animal is on a drug that could lower T4, then what should we do?
take the animal off drugs for 2 weeks before testing T4
Do we often test T3?
tests available but we don't often test
What is the biologically active hormone in T3?
What is free T4?
- non protein bounding hormone
- free hormone available to cells
What percent of T4 is protein bound in dogs?
Is the free T4 test expensive or inexpensive?
What should be elevated in hypothyroidism?
Is total T4 or free T4 the most accurate to test?
What is low in 10% of euthyroid dogs?
What is the most accurate test for hypothyroidism?
TSH response test
How do we do a TSH response test? What is considered abnormal and what is considered normal?
- collect presample
- give TSH
- collect post sample
- abnormal is there is no increase
- normal if there is an increase in T4 levels post sample
What does the TSH response test measure?
What is the thyroglobulin auto Ab test?
new ELISA test that tests for antibodies found in many hypothyroid dogs
If the typical hypothyroid signs are seen, which tests should we use?
total T4 and TSH level
If there are less common tests seen for hypothyroidism, what tests should we use?
- use free T4 using equilibrium dialysis method
- also run T4 and TSH levels
Up to 30% of dogs with nonthyroidal illness and low total T4 will have elevated _____.
Hyperthyroidism is common in what species?
What is hyperthyroidism usually due to?
hyperplasia or neoplasia
What are the signs of hyperthyroidism?
increased activity, PU, PD, voracious appetite, lose weight, increased HR
What do the tests show for hyperthyroidism?
- elevated T4 levels
- if normal, but showing signs, retest in 1 - 2 weeks
What are the different types of Diabetes Mellitus?
types I and Ii
If diabetes mellitus is left untreated, what can happen?
ketoacidosis and then they will go into shock and die
What does type I diabetes do?
destruction of pancreatic beta cells
What are pancreatic beta cells?
cells that secrete insulin
Type I diabetes mellitus is _____.
What does type II diabetes mellitus do?
- decreases the number of insulin receptors on tissues
- cells become insensitive to the effects of insulin
Type II diabetes mellitus is _____.
What does insulin do?
regulates glucose and facilitates the movement of glucose out of blood
What are the predisposing factors for diabetes mellitus?
Which gender is more likely to get diabetes mellitus?
Which breeds of dogs are more prone to diabetes mellitus?
- minature schnauzer
- miniature pinscher
- german shephard
What type of cats are more prone to diabetes mellitus?
How does obesity cause diabetes mellitus?
What drugs can cause diabetes?
- chronic glucocorticoid administration (depo medro)
What are glucose levels affected by?
- reproductive status
- test (collecting blood from excited animals can increase glucose)
What kind of glucose sample do we want?
a fasted sample
Once we collect our sample to test glucose, what do we need to do immediately?
separate serum asap
How can we diagnose diabetes mellitus?
- clinical signs may be obvious
- glucose tolerance tests
How do we do glucose tolerance tests?
- give oral or IV glucose
- take samples every 30 minutes
- measure glucose levels
- should be to WNL in 90 minutes for dogs (180 minutes for cats)
What are insulinomas?
insulin tumor in the pancreas
What animal are insulinomas common in?
- but also may be seen in dogs
Does xylitol increase or decrease insulin?
How do we test for hypoglycemia?
measure insulin levels during periods of weakness
What is diabetes insipidus?
deficiency of ADH
What is ADH?
- antidiuretic hormone
- absorbs water into the blood
An animal who has diabetes insipidus is unable to do what with their urine?
unable to concentrate urine
What are the clinical signs of diabetes insipidus?
As long as the animal with diabetes insipidus has access to water all the time, will it be okay?
Is diabetes insipidus common?
no, its uncommon
Why is diabetes insipidus difficult to diagnose?
must differentiate from other diseases with similar signs
How do we diagnose diabetes insipidus?
- eliminate other causes
- water deprivation overnight - if urine SG is still low in the morning then the patient is not concentrating urine
- Pitressin challenge
What is the Pitressin challenge?
give pitressin and test the urine SG to see if the urine is now concentrated
What is another name for hyperadrenocorticism?
What causes hyperadrenocorticism?
- pituitary tumor (PDH) - 80% of cases
- adrenal cortical tumor
- iatrogenic - we caused it using steroids
What does iatrogenic mean?
we caused the condition with treatments
Which species is hyperadrenocorticism common in?
dogs and ferrets
What is elevated with hyperadrenocorticism?
hormone (cortisol) levels
Which dogs are pituitary dependent?
- german shepherds
- boston terriers
Which kinds of dogs are adrenal dependent?
What kind of treatments do we do that causes hyperadrenocorticism in dogs (iatrogenic)?
- chronic glucocorticoid administration (especially powerful steroids like depomedrol)
- a steroid like pred once a day would not cause hyperadenocorticism
What are the clinical signs of hyperadrenocorticism?
- abdominal enlargement
- muscle weakness, lethargy
- poor haircoat
- reproductive disorders
Why do we see an enlarged abdomen with hyperadrenocorticism?
- thinning of the abdominal muscles
- not due to fluid
What is the first clinical signs clients typically notice of hyperadrenocorticism?
What is elevated in ferrets with hyperadrenocorticism?
What will we see on a CBC of an animal with hyperadrenocorticism?
stress leukogram - leukocytosis, neutrophilia, monocytosis, lymphopenia, eosinopenia
Other than doing a CBC, we can also run a chem blood panel for hyperadrenocorticism. What will be elevated on the blood test?
What does a urinalysis look like from an animal with hyperadrenocorticism?
- SG below 1.015
- may see signs of a urinary tract infection (to rule out cystitis there will not be leukocytes)
- mild proteinuria
What other factors can cause hormone levels to be elevated?
- drugs (steroids)
Why would we run a stimulation test for hyperadrenocorticism?
to determine the location of the problem (pituitary dependent or adrenal dependent)
Is there an Idexx SNAP cortisol test for hyperadrenocorticism?
yes, just test us if cortisol is elevated
What is the ACTH stimulation test for?
to diagnose hyperadrenocorticism or monitor treatemtn
How do we do the ACTH stimulation test?
- collect presample
- give ACTH
- collect sample in 60 minutes and 90 minutes
- expect increase of cortisol
- may be WNL with hyperadrenocorticism
What is the low dose dex suppression test?
most reliable test for hyperadrenocorticism
How do we do the low dose dex suppression test?
- collect pretest sample
- give dex 0.01 mg/kg IV
- collect samples at 4 hours and 8 hours
- cortisol levels will be elevated in hyperadrenocorticism
What is the high dose dex suppression test?
test used after hyperadrenocorticism has been confirmed in order to see if it is pituitary dependent or adrenal dependent
How do we do the high dose dex suppression test?
- collect pretest sample
- give 0.1 mg/kg dex IV
- collect sample in 8 hours
- if suppressed, then it is pituitary dependent
What is the combination test?
combined dexamethasone suppresion/corticotropin stimulation test
How do we do the combination test?
- collect predrug sample
- give dex at 0.1 mg/kg
- collect post sample at 2 - 4 hours
- give cosyntropin or ACTH gel
- collect sample one post injection
How do we interpret the combination test?
- see exaggerated cortisol response to ACTH
- if normal response to ACTH and no cortisol depression then it is pituitary dependend hyperadrenocorticism
What is the endogenous corticotropin assay?
- test that will be elevated with pituitary dependent hyperadrenocorticism
- will be normal to low with adrenal dependent
Do we need special tubes for the endogenous corticotropin assay?
- yes, tubes containing aprotinin
- must get them from the lab
Other than a urinalysis, what kind of urine test can we do to help us diagnose hyperadrenocorticism?
- urine cortisol:creatinine ratio - done by RIA
- will be increased in hyperadrenocorticism
Is hyperadrenocorticism common in cats?
no, its rare in cats
Which test should we use to test for hyperadrenocorticism in cats?
- higher dex suppression test - give dex at 1 mg/kg IV, post sample at 6 and 8 hours
- will be elevated with hyperadrenocorticism
What is another name for hypoadrenocorticism?
What do animals with hypoadrenocorticism lack?
lack of aldosterone
How do animals get hypoadrenocorticism?
- can occur with iatrogenic cushings if we stop steriods suddenly (adrenal crisis)
What are the clinical signs for hypoadrenocorticism?
- generalized weakness
- nonspecific GI disturbances (vomiting)
- addisonian crisis - shocky, decreased HR, decreased BP, decreased temp
How do we diagnose hypoadrenocorticism?
- no stress leukogram on CBC
- hyperkalemia (increase in potassium)
- hyponatremia (decrease in sodium)
- ACTH stimulation test - cortisol levels will be low
What is the treatment for hypoadrenocorticism?
monthly injection of the steroid percorten v for the rest of the animals life
What are hyperparathyroidism usually secondary to?
- renal disease
- nutritional deficiency (calcium)
How do animals get hyperparathyroidism?
- low calcium levels stimulate parathormone (PTH) release
- PTH then pulls calcium from bone
Hyperparathyroidism is common in which types of animals?
How do we diagnose hyperparathyroidism?
- clinical signs of weakness and fractures
- measure calcium and phosporous
What could hypercalcemia be due to?
- parathyroid neoplasia
- primary hyperparathyroidism
- bone disease
- cholecalciferol toxicity
When do we usually see hypercalcemia?
young, growing animals
What are the signs of hypercalcemia?
- cardiac arrhythmias
- dystrophic calcification (kidneys turn to stone)
How do we diagnose hypercalcemia?
- various blood tests
- PTH assay