SA Endocrine Diseases Flashcards
(194 cards)
1
Q
What is the most common endocrinopathy of cats?
A
Hyperthyroidism
2
Q
What is the thyroid pathology of hyperthyroidism?
A
Adenomatous hyperplasia or adenoma resulting in autonomous production of thyroid hormones
3
Q
T/F: Hyperthyroidism in cats most commonly involves both lobes but can be unilateral.
A
T
4
Q
In a hyperthyroid cat, what do you expect to happen to the T4 and TSH levels?
A
Increased T4, decreased TSH
5
Q
What are the most common signs associated with hyperthyroidism? (5 answers)
A
Weight loss with good appetite, PU/PD, vomiting, diarrhea, unkempt hair coat
6
Q
In majority of cats with hyperthyroidism, you may hear a sinus tachycardia on auscultation. In some cases, you may hear a heart murmur or gallop rhythm. What does this suggest is occurring secondary to the hyperthyroidism?
A
HCM
7
Q
Most hyperthyroid cats will have a __________ or __________ creatinine.
A
Normal or decreased
8
Q
What is the most common cause of hypothyroidism in cats?
A
Iatrogenic after treatment of hyperthyroidism
9
Q
Cats that develop worsening azotemia or new azotemia while on methimazole that have a low to low-normal T4 should have what other test performed?
A
cTSH
10
Q
Why does a low T4 alone in a cat not confirm hypothyroidism?
A
Presence of nonthyroidal illnesses (CKD, neoplasia, diabetes, hepatic disease) can lower serum T4 in euthyroid cats
11
Q
When should you evaluate a patient that had undergone radioiodine therapy for permanent iatrogenic hypothyroidism?
A
3 months after treatment or earlier if overt clinical signs of hypothyroidism develop or there is marked worsening of azotemia
12
Q
What is the drug of choice for treating hypothyroidism in dogs and cats?
A
Levothyroxine
13
Q
When should you administer levothyroxine in regards to feeding time?
A
Give without food 1 hour before a meal or 3 hours after a meal
14
Q
Hypothyroidism can lead to a(n) increased/decreased GFR, which will improve/worsen kidney function and survival time.
A
Decreased, worsen
15
Q
If cats being treated with methimazole have a low to low-normal T4 or develop a worsening azotemia, should you increase/decrease the dose of Methimazole and by what percentage?
A
Decrease dose by 25-50%
16
Q
What is the treatment protocol for a cat that is still hypothyroid 6 months after treatment with radioiodine?
A
Treat regardless of presence of azotemia
17
Q
What are the most common etiologies of canine hypothyroidism?
A
Lymphocytic thyroiditis and idiopathic thyroid atrophy
18
Q
What is the most common signalment for canine hypothyroidism?
A
Young adult to middle aged medium to large-breed dogs
19
Q
The general signs of canine hypothyroidism occur due to a(n) increased/decreased metabolic rate. (choose one)
A
Decreased
20
Q
What are the general signs associated with canine hypothyroidism? 4 answers.
A
Lethargy, weakness, obesity, exercise intolerance
21
Q
Describe the alopecia associated with canine hypothyroidism (location, bilateral/unilateral, pruritic or not, etc.)
A
Earliest loss occurs in areas of friction (neck and tail) and then becomes bilaterally symmetrical over trunk (spares head and distal extremities)
Non-pruritic unless secondary infection
Hyperpigmentation common
22
Q
What is Myxedema?
A
Non-pitting edema that causes a puffy appearance of face (tragic facial expression); sometimes seen with canine hypothyroidism
23
Q
What laboratory findings may you see on CBC/Chem associated with hypothyroidism in dogs?
A
Hypercholesterolemia and normocytic, normochromic, mild, non-regenerative anemia
24
Q
How do you make a diagnosis of hypothyroidism in dogs?
A
History of clinical signs and low T4 with increased TSH
25
What is the most common test used to diagnose hypothyroidism?
T4
26
Why do nonthyroidal illnesses and lymphocytic thyroiditis pose a challenge when trying to diagnose hypothyroidism?
Nonthyroidal illnesses can lower T4 in a euthyroid dog and lymphocytic thyroiditis creates T4 autoantibodies that can falsely elevate serum T4 in a true hypothyroid dog
27
What is the most accurate single test for diagnosis of hypothyroidism in dogs because it is less often affected by nonthyroidal illnesses but is used less frequently than T4 due to cost and availability?
Equilibrium dialysis assay (free T4)
28
What breeds tend to normally have lower T4 and fT4 levels than other breeds?
Sighthounds
29
Name 4 drugs/classes of drugs that can affect thyroid function tests (often lowers T4)
Corticosteroids, Sulfonamides, Phenobarbital, Clomipramine
30
If you suspect a dog has hypothyroidism but presents to you for being sick, when should you perform the thyroid function tests?
If you can, resolve illness before testing for hypothyroidism
31
T/F: Thyroiditis may or may not progress to hypothyroidism
T
32
What test is not affected by autoantibodies that can help you determine if a patient is truly hypothyroid or euthyroid?
fT4 by equilibrium dialysis
33
You have diagnosed a dog with hypothyroidism and have started him on Levothyroxine. When should you schedule a recheck? Be specific.
Recheck 6-8 weeks after starting treatment and measure serum levels 4-6 hours post-pill.
34
When can you tell owners they should start to see results once starting their dog on levothyroxine?
Increased activity, improved attitude, and weight loss in 1-2 weeks; dermatologic signs will require months to resolve
35
What should you do if a canine patient you are treating for hypothyroidism develops clinical signs of hyperthyroidism (PU/PD, panting, hyperactivity, polyphagia)?
Stop treatment for 2-3 days and then re-institute at 50-75% of original dose
36
A 6-year-old dog presents with central vestibular disease. A total T4 is below the reference range. What is your interpretation and recommendations?
Central vestibular signs can be seen with hypothyroid patients, but the low T4 may also be from nonthyroidal illness. Would recommend fT4 by ED +/- TSH
37
What are 2 signs that are specific to the hypercalcemia?
Generalized weakness and PU/PD
38
What are 5 general clinical signs that are non-specific to the hypercalcemia, but rather are related to the underlying disease?
Lethargy, anorexia, vomiting, diarrhea, and weight loss
39
With any elevation of hypercalcemia, what should be on your differential list?
Neoplasia
40
What is the most common cause of hypercalcemia in a dog/cat that feels well?
Spurious hypercalcemia
41
What are 4 causes for a spurious hypercalcemia?
Lipemic serum, hemolyzed serum, hemoconcentration (dehydration), or a young, growing animal
42
What can you do to distinguish hypercalcemia induced renal failure from renal failure induced hypercalcemia?
Measure ionized calcium
43
Explain how hypercalcemia can lead to azotemia (lack of perfusion to kidneys).
Excess calcium causes vasoconstriction to renal arteries -> azotemia
44
If azotemia is present and there is an increased ionized calcium, what is your interpretation?
Hypercalcemia induced renal failure
45
If azotemia is present and ionized calcium is normal, what is your interpretation?
Renal failure induced hypercalcemia
46
If the patient has repeatable hypercalcemia but not azotemia, do you still need to measure an ionized calcium?
No
47
What are 4 history/physical exam findings in addition to the hypercalcemia that would put neoplasia higher on your differential list?
Peripheral lymphadenopathy, palpable mass, long bone pain, and/or fever
48
What are 3 history/physical exam findings in addition to the hypercalcemia that would put granulomatous disease higher on your differential list?
Long bone pain, fever, and/or tachypnea/dyspnea/cough
49
What is the most common neoplasia in dogs and cats causing hypercalcemia?
Lymphoma
50
What are the 3 most common types of neoplasia causing hypercalcemia?
Lymphoma, apocrine gland adenocarcinoma of anal sac, and multiple myeloma
51
In a canine patient with hypercalcemia, what should always be included in your physical examination?
Rectal exam
52
What is the mechanism of hypercalcemia of malignancy?
Secretion of PTHrp, calcitriol, and/or cytokines by tumor cells
53
What is the typical calcium/phosphorus pattern and animal health (well vs. sick) associated with hypercalcemia of malignancy?
High tCa, high iCa, and normal or decreased PO4 (unless concurrent renal injury - then PO4 will be elevated);
Animal feels well; note that the calcium/phosphorus pattern can be anything with neoplasia!
54
What are the 2 most common causes of hypervitaminosis D?
Ingestion of cholecalciferol rodenticide or psoriasis cream (contains excessive vitamin D)
55
What is the calcium/phosphorus pattern associated with hypervitaminosis D? How does the animal feel overall?
High tCa, high iCa, and high PO4 (often have concurrent renal injury);
Animal feels sick
56
What are the 2 mechanisms of hypercalcemia due to typical hypoadrenocorticism in dogs?
1. Hemoconcentration leads to hyperproteinemia (albumin) -> more calcium to measure
2. Decreased GFR -> decreased renal clearance
57
What is the typical calcium/phosphorus pattern associated with typical hypoadrenocorticism in dogs and how do these patients feel?
High tCa, normal iCa, and high PO4 (due to concurrent prerenal azotemia);
Dog feels sick
58
What is the mechanism of renal failure induced hypercalcemia?
Secretion of excess PTH due to chronic renal secondary hyperparathyroidism (becomes autonomous)
59
Why does chronic kidney failure lead to hyperphosphatemia?
There is decreased renal clearance of phosphorus, so it gets reabsorbed in the blood -> hyperphosphatemia
60
Describe renal secondary hyperparathyroidism.
The last step in the synthesis of vitamin D occurs in the kidneys and requires PTH. Kidney failure -> less vitamin D produced -> less calcium absorption from the gut -> hypocalcemia -> stimulates PTH secretion from parathyroid glands -> restores normal calcium -> kidney failure still present, so parathyroid keeps secreting PTH (becomes autonomous) -> hypercalcemia
61
What is the typical calcium/phosphorus pattern associated with chronic kidney failure and how does the patient feel?
High tCa, normal iCa, and high PO4 (due to renal injury);
Patient can feel well or sick
62
What is the mechanism associated with granulomatous disease causing hypercalcemia?
Fungal organisms initiate a granulomatous (macrophage-based) inflammation around them, and those macrophages secrete calcitriol
63
What is the typical calcium/phosphorus pattern associated with granulomatous disease and how does the patient typically feel?
High tCa, high iCa, and normal or high PO4 (due to renal injury);
Patient feels sick usually
64
What is the mechanism of primary hyperparathyroidism in dogs?
Secretion of excess PTH by a parathyroid gland tumor (adenoma); kidneys are functioning as normal
65
What is the typical calcium/phosphorus pattern associated with primary hyperparathyroidism and how do those dogs typically feel?
High tCa, high iCa, and normal or low PO4 (almost never has renal injury);
Dogs will feel well
66
What is the second most common cause of hypercalcemia in cats and what is the typical pattern of calcium/phosphorus associated with it? How do the cats feel?
Idiopathic hypercalcemia;
High tCa, high iCa, and normal PO4;
Cats can feel well or sick
67
If your patient is hypercalcemic and primary hyperparathyroidism is at the top of your differential list, what would you do to diagnose it?
Measure iCa, PTH, and PTHrp
68
If your patient is hypercalcemic and the owner tells you there was an exposure to rat bait, what should you do to confirm this is hypervitaminosis D causing the hypercalcemia?
Measure serum 25-hydroxyvitamin D levels
69
What are 5 clinical signs related to hypocalcemia? (Do your best)
Muscle tremors/fasciculations, facial rubbing, stiff gait, behavior changes (restless, anxious, aggressive), and/or seizures
70
If you have a patient that is hypocalcemic, what should you rule out first?
Hypoalbuminemia
71
If your patient is hypocalcemic and has a history of recently whelping or is soon to whelp, what would be at the top of your differential list?
Eclampsia
72
If calcium is low and phosphorus is normal, what would be your top 3 differentials?
Acute pancreatitis, eclampsia, or malabsorptive GI disease
73
Are you more likely to see hyper- or hypocalcemia with chronic kidney failure?
Hypercalcemia
74
Are you more likely to see hyper- or hypocalcemia with acute kidney injury and urinary tract obstruction?
Hypocalcemia
75
What is the mechanism of hypocalcemia caused by acute pancreatitis?
Calcium precipitation with saponified peripancreatic fat
76
What is the mechanism of hypocalcemia caused by eclampsia?
Mobilization of calcium into milk production and/or fetal skeletal development
77
What is the mechanism of hypocalcemia caused by malabsorptive GI disease in dogs?
Poor intestinal calcitriol absorption and/or calcitriol loss bound to albumin
78
What is the mechanism of hypocalcemia caused by owners using a phosphate containing enema (aka fleet enema)?
Phosphorus is absorbed by colonic wall -> body responds with mass law effect -> rapidly dropping calcium levels
79
What is the mechanism of hypocalcemia caused by acute kidney injury or urinary tract obstruction?
Acute drop in GFR -> hyperphosphatemia -> mass law driven hypocalcemia
80
What is the mechanism of hypocalcemia caused by primary hypoparathyroidism in dogs?
Secretion of no PTH by immune-mediated destruction of the parathyroid gland
81
What is the typical calcium/phosphorus pattern associated with primary hypoparathyroidism in dogs?
Low tCa, low iCa, and high PO4
82
If you are concerned for hypoparathyroidism, what should you do to confirm it?
Measure iCa, PTH, and PTHrp
83
If you are concerned for acute pancreatitis, what should you do to diagnose it?
Perform abdominal ultrasound and/or PLI
84
With hypocalcemia and hypercalcemia, what should your goals of treatment be?
Treat the underlying disease
84
With hypocalcemia and hypercalcemia, what should your goals of treatment be?
Treat the underlying disease
85
When is acute, emergent (and non-specific) therapy indicated for treatment of hypocalcemia?
When clinical signs of hypocalcemia are present
86
What is used for acute, emergent treatment of hypocalcemia?
Calcium gluconate IV (slow and "to effect")
87
What treatment is used for chronic hypocalcemia or life-long therapy?
Calcium carbonate (TUMs) PO and/or calcitriol PO
88
What is the treatment protocol for acute and emergent cases of hypercalcemia? (3 answers)
IV fluids (0.9% NaCl), furosemide (once euhydrated), and glucocorticoids;
All promote calciuresis and steroids will also inhibit bone Ca2 release
89
Why might we see an unconcentrated urine (USG <1.035) in a cat with hyperthyroidism?
Thyroid hormone increases renal blood flow and GFR and make the animals PU/PD
90
Is an unconcentrated urine in a suspected hyperthyroid cat definitive for thyroid disease or kidney disease?
No, can be <1.035 for either one (can't differentiate)
91
Why might creatinine be low in a hyperthyroid patient?
Muscle wasting
92
What is your interpretation of a cat that has clinical signs associated with hyperthyroid disease, but the patient's TT4 is mid to high normal and high fT4?
Could be early/mild hyperthyroid or concurrent nonthyroidal illness
93
How do you get a definitive diagnosis of hyperthyroidism in cats?
By documenting persistently elevated thyroid hormones in a cat with at least one or more clinical signs of hyperthyroidism
94
What is your interpretation of a cat with clinical signs associated with hyperthyroidism but the TT4 is low to low-normal and the fT4 is high?
Likely euthyroid with nonthyroidal illness
95
In order to know the kidney function in a hyperthyroid cat, we must remove the effects of thyroid disease. How do we do this?
Treat with Methimazole and assess kidney function 4 weeks after the cat becomes euthyroid
96
What are 4 treatment options for hyperthyroid cats?
Methimazole, Surgical thyroidectomy, radioiodine therapy, or iodine-restricted diet
97
What is the mechanism of methimazole?
Blocks thyroid peroxidase -> no more thyroid hormone production
98
How long does Methimazole take to become effective?
2-4 weeks (still already made thyroid hormones in the body)
99
If within the first 3 months of hyperthyroid treatment the cat develops GI signs with oral methimazole, what can you do to still manage the thyroid disease?
Switch to transdermal methimazole
100
What is a common side effect that tells us the cat is becoming intolerant to methimazole?
Facial pruritis
101
What is the follow up protocol for starting cats on Methimazole?
Recheck patient in 4 weeks (CBC, Chem, UA, T4);
Recheck again in 2 months if T4 normal and no side effects;
Then periodically if stable
102
What are the risks associated with surgical thyroidectomy? (2 answers)
Hypothyroidism and hypoparathyroidism (hypocalcemia -> life threatening)
103
T/F: Radioiodine emits beta particles that destroys abnormal thyroid tissue but spares normal tissue.
T
104
What monitoring is involved when radioiodine is used as treatment for hyperthyroidism?
Chemistry, UA, T4/TSH 1- month post-treatment, and again at 3 months and 6 months.
105
If clients opt to use an iodine-restricted diet, how long after starting the diet should they see clinical signs improve?
Appx. 4 weeks
106
Can cats that are not hyperthyroid eat iodine-restricted diets?
Yes, but the food is expensive
107
What cells of the endocrine pancreas are responsible for making insulin?
Beta cells
108
Which type of diabetes is more common in the dog? What about in the cat?
Dog = Type I diabetes mellitus
Cat = Type II diabetes mellitus
109
Which type of diabetes is considered insulin-dependent?
Type I diabetes mellitus
110
With type I diabetes mellitus there is a loss of beta cells, resulting in a(n) relative/absolute hypoinsulinemia. (Choose one)
Absolute
111
With type II diabetes mellitus, there is impairment of the beta cells, resulting in a(n) relative/absolute hypoinsulinemia. (Choose one)
Relative
112
What causes type I diabetes mellitus in dogs?
Immune-mediated destruction ("insulitis")
113
What causes type II diabetes mellitus in cats?
Often concurrent disease causing insulin resistance
114
What are 5 potential causes of insulin resistance that could contribute to type II diabetes mellitus?
Genetic factors, obesity, insulin-antagonistic drugs (i.e. progesterone or glucocorticoids), endocrinopathies (insulin-antagonistic disease), and diseases secreting inflammatory cytokines (IL-1, IL-6, TNF alpha; pancreatitis, aspiration pneumonia, bacterial gallbladder infection, etc.)
115
Diabetes mellitus occurs due to an insulin deficiency, which promotes hyperglycemia. Why does hyperglycemia occur? (3 answers)
Decreased tissue utilization of glucose, increased hepatic glycogenolysis, and increased hepatic gluconeogenesis
116
Why does glucosuria occur in a diabetic dog/cat?
Amount of glucose exceeds the renal threshold of proximal tubule to reabsorb the filtered glucose, so it spills out into the urine
117
What are the 4 clinical signs associated with diabetes mellitus in dogs and cats?
PU/PD, weight loss, and polyphagia
118
Why are diabetic patients PU/PD?
Glucose is an osmotically active substance, and water follows anything that is osmotically active. Glucose spills into the urine, so water follows -> polyuria. There is a compensatory polydipsia to maintain hydration
119
Why do diabetic animals lose weight?
Lack of an ability of cells to utilize glucose for energy and storage -> weight loss
120
What is normal blood glucose in the dog and cat?
Dog = 80-120 mg/dL
Cat = 80-140 mg/dL
121
When the body cannot utilize glucose for energy, what will it use as an alternative source of energy to provide to the cells?
Fat to form ketones in the liver
122
What is a complication of diabetes mellitus that occurs as a result of some other insulin-resistant disease in the body?
Diabetic ketoacidosis
123
How will a DKA patient present to you?
Vomiting, diarrhea, not eating, lethargic, etc.
124
Like glucose, what is another osmotically active substance that can lead to acidosis when produced in large quantities?
Ketone bodies
125
Diabetic patients can have increased liver enzymes on blood chemistry. Will ALT or ALP be more elevated?
ALP > ALT (vacuolar hepatopathy due to excess fat mobilized in body)
126
What changes do you expect to see on a blood chemistry in patients suspected to have diabetes mellitus? 4 answers.
Hyperglycemia, increased liver enzymes, hypercholesterolemia, and hypertriglyceridemia
127
If a patient is PU/PD, what would you expect their USG to be? Does this rule apply to diabetics? Why or why not?
Would expect it to be dilute (hyposthenuric); glucose artificially elevates USG, so we will see a concentrated urine in diabetic patients (>1.020) or isosthenuric because water follows glucose and can dilute the urine
128
What criteria does a patient need to make a diagnosis of diabetes mellitus?
Appropriate clinical signs, persistent fasting hyperglycemia, and persistent fasting glucosuria
129
In uncomplicated cases of diabetes mellitus, what is the first choice of insulin for cats?
Glargine (aka Lantus, Sanofi)
130
In uncomplicated cases of diabetes mellitus, what is the first choice of insulin for dogs? 2 answers.
NPH (Novolin N, Humulin N) OR Lente (Vetsulin)
131
If we are using insulin to treat DKA, do we want short-acting or long-acting insulin?
Short-acting
132
For all long-acting insulin types, how do we typically dose it? (Don't be specific with number)
Dosed twice daily after a meal
133
If a glucose curve shows uncontrolled numbers, but the owner describes an animal that is doing well at home and not showing clinical signs, should you change the insulin dose?
No
134
When should you perform a glucose curve in a diabetic patient?
During initial 1-2 months following diagnosis (to get animal regulated) and/or anytime a diabetic animal becomes poorly regulated
135
What is a blood glucose curve used to determine?
If/what adjustments to the insulin TYPE or DOSE are needed
136
Following an insulin type change or dose adjustment, when should a recheck blood glucose curve be performed?
7-10 days following change
137
What test can be performed to differentiate between stress hyperglycemia and true diabetes mellitus?
Measure fructosamine
138
What is a somogyi response?
Insulin "overdosing" that occurs when the insulin dose increases based on spot BG -> results in either rapid decrease in BG or absolute hypoglycemia -> body responds by secreting insulin-antagonizing hormones -> very profound rebound hyperglycemia
139
What are 3 additional clinical signs specific to dogs with diabetes mellitus?
Bilateral cataracts, poor haircoat, and abdominal distension (lipid accumulation in liver -> hepatomegaly -> abdominal distension)
140
What are the goals for treating diabetes mellitus in dogs and cats? 3 answers
Eliminate owner-observed clinical signs, prevent hypoglycemia, and minimize cataract formation
141
What type of diet is recommended for diabetic dogs?
High fiber, low simple carbohydrate diet
142
What are 2 additional clinical signs of diabetes mellitus that are specific to cats?
Plantigrade stance and poor haircoat
143
Your feline patient you suspect has diabetes mellitus has a mild to moderate increase in BG (<270 mg/dL), no concurrent glucosuria, and the fructosamine was normal. What is your interpretation?
Stress hyperglycemia
144
What diet is recommended for a diabetic cat?
High protein, low simple carbohydrate diet and restrict calories if planned weight loss secondary to obesity is needed
145
What is the ability to induce diabetic remission based on? 2 answers.
Insulin resistance is rapidly treated or removed (if present) and/or reversal of glucotoxicity via early initiation of insulin therapy
146
When does diabetic remission usually occur in the cat?
During the first 3-4 months of therapy
147
Can dogs go into diabetic remission?
No - will require insulin injections for the rest of their life
148
What is the name for the endocrine disease in dogs in which the adrenal gland is making excess cortisol?
Hyperadrenocorticism aka Cushing's
149
Which type of hyperadrenocorticism is more common: Pituitary dependent or adrenal dependent?
Pituitary dependent
150
Describe pituitary dependent hyperadrenocorticism
Benign (adenoma) tumor or hyperplasia of pituitary secretes excess ACTH -> stimulates adrenal gland to make excess cortisol -> results in endogenous cortisol secretion
151
Describe adrenal dependent hyperadrenocorticism
Benign (adenoma) or malignant (carcinoma) tumor of adrenal gland that makes excess cortisol -> excess endogenous cortisol secretion
152
How do dogs get iatrogenic hyperadrenocorticism?
Excess exogenous cortisol administration from prescribing steroids
153
What are the common clinical signs associated with hyperadrenocorticism? (Do your best)
PU/PD, truncal alopecia (non-pruritic), polyphagia, abdominal distension, panting, muscle wasting/weakness
154
Why are Cushingoid patients PU/PD? (2 answers)
Excessive cortisol inhibits ADH binding to its receptor in the kidney -> water is not retained -> PU/PD;
Also inhibition of ADH release from posterior pituitary
155
Why do Cushingoid patients have abdominal distension?
Hepatomegaly ("steroid hepatopathy") that occurs due to glycogen accumulation in liver
156
What can you expect so see on a CBC/Chem of a patient with hyperadrenocorticism?
CBC - stress leukogram, thrombocytosis
Chem -normal to mild hyperglycemia, increased ALP > ALT, hypercholesterolemia, hypertriglyceridemia
157
What would you expect the USG to be in a patient with hyperadrenocorticism? Is there protein present, too?
USG <1.020; proteinuria; potentially UTI because they are more prone like diabetic patients
158
What are the 3 screening tests for hyperadrenocorticism?
1. Urine Cortisol:Creatinine Ratio (UC:CR)
2. Low dose dex suppression test (LDDST)
3. ACTH stim test
159
When would you want to perform a urine cortisol:creatinine ratio in a dog?
If you want to rule out Cushing's (aka when you don't think the animal has HAC)
160
You perform a urine cortisol:creatinine ratio on a dog and the test came back negative (below reference range). What is your interpretation? What if the test came back positive (above reference range)?
Negative - This animal does not have Cushing's
Positive - may have Cushing's, need to run another test
161
If you perform a low dose dex suppression test in a normal animal, what would you expect their cortisol level to be?
Should be less than the reference interval (complete suppression)
162
You perform a low dose dex suppression test in a dog you suspect has hyperadrenocorticism. The results show a 4 and 8-hour cortisol that is above the reference interval, and both numbers are increased >50% of 0-hour cortisol. What is your interpretation?
This animal likely has HAC; don't know if it is pituitary dependent or a functional adrenal tumor
163
What drug is administered to a patient for an ACTH stimulation test?
Cosyntropin
164
You perform an ACTH stimulation test in an animal you suspect has Cushing's. The 1-hour cortisol is above the reference interval. What is your interpretation?
This is consistent with HAC
165
Are you more likely to have false positives for HAC with the LDDST or the ACTH stim test?
LDDST has more false positives than ACTH stim test
166
If you have an animal that is very stressed in hospital but you want to run a test to confirm if he/she has Cushing's, what test would you run to get the most accurate results? (i.e., one that is not affected by stress)?
ACTH stim test best;
LDDST could give you a false positive if patient is stressed in hospo
167
What diagnostic can you perform to differentiate between pituitary dependent and adrenal dependent HAC?
Abdominal ultrasound
168
What do you look for on abdominal ultrasound to differentiate pituitary dependent vs. adrenal dependent HAC?
Adrenal dependent -> look for adrenal tumor; other adrenal gland will be atrophied
Pituitary dependent -> both adrenals will be enlarged (no tumor on adrenal glands)
169
You perform a LDDST on a dog you suspect has Cushing's. Both the 4 and 8-hour post Dex samples are above the reference range but one or both is/are less than 50% of the 0-hour cortisol. What is your interpretation?
This patient likely has pituitary dependent HAC because there is some suppression of cortisol.
170
What is the drug of choice for treating Cushing's disease in dogs? What is its mechanism of action?
Trilostane (Vetoryl) -> suppresses cortisol production in the adrenal gland
171
What is the ideal method of treatment for pituitary dependent vs. adrenal dependent HAC?
Pituitary dependent -> treat with Trilostane for rest of life;
Adrenal dependent -> ideally, surgery to remove tumor. But, can still use trilostane
172
What is the ideal method of treatment for pituitary dependent vs. adrenal dependent HAC?
Pituitary dependent -> treat with Trilostane for rest of life;
Adrenal dependent -> ideally, surgery to remove tumor. But can still use trilostane
173
What disease in dogs occurs as a result of a deficiency of cortisol only or of cortisol and aldosterone?
Hypoadrenocorticism (aka Addison's Disease)
174
Describe typical hypoadrenocorticism
Absence of glucocorticoids and mineralocorticoids; more common than atypical
175
Describe atypical hypoadrenocorticism
Absence of glucocorticoids ONLY; bilateral immune mediated zona glomerulosa destruction ONLY
176
Describe iatrogenic hypoadrenocorticism
Due to abrupt discontinuation of exogenous glucocorticoids or side effect of a drug used to treat hyperadrenocorticism (mitotane, trilostane)
177
What are the common signs of typical hypoadrenocorticism?
PU/PD, hypovolemic shock (PU without the PD) +/- bradycardia; can also have signs of atypical hypoadrenocorticism but these predominate
178
What are the common signs of atypical hypoadrenocorticism? (There's many, do your best)
Vomiting, diarrhea, weight loss, hemorrhage, poor appetite, lethargy, weakness, seizures
179
Why might an Addisonian be PU/PD?
PU/PD occurs due to osmotic diuresis secondary to chronic Na+ loss through the kidneys (lack of aldosterone)
180
Why would an Addisonian patient have bradycardia?
Due to hyperkalemic induced effects on cardiac myocyte depolarization and repolarization
181
Addisonian crisis occurs due to a lack of _____________, which leads to a loss of sodium and water, causing the patient to become hypovolemic and present with signs of shock.
Aldosterone
182
Patients with typical Addison's disease have a deficiency of both cortisol and aldosterone. What do you expect the sodium and potassium concentrations in the blood?
Hyponatremia and hyperkalemia
183
What would you expect to see on a CBC in a patient with hypoadrenocorticism?
CBC - mild to moderate nonregenerative, normochromic and normocytic anemia, lack of stress leukogram, and normal platelets
184
What changes on serum chemistry from an Addisonian patient would you expect to see that mimics renal failure? 5 answers.
Prerenal azotemia, hypercalcemia, hyponatremia, hyperkalemia, and mild metabolic acidosis
185
What changes on serum chemistry from an Addisonian patient could you see that mimics hepatic insufficiency or protein losing enteropathy? (5 answers)
Hypoglycemia, hypoalbuminemia, increased liver enzymes, hypocholesterolemia, and normal sodium and potassium (could be increased if typical Addison's due to aldosterone deficiency too)
186
What would you expect the USG of a patient with hypoadrenocorticism to be?
Dilute urine (USG 1.008-1.020)
187
A dog comes in for regurgitation and you diagnose him/her with megaesophagus. What endocrine disorder must you rule out?
Addison's Disease
188
You perform bloodwork on a patient and need to rule out renal failure vs. hypoadrenocorticism. You perform a baseline cortisol, and it is less than 2. What is your interpretation?
This likely isn't renal failure, but it still could be HOC.
189
You suspect a dog may have hypoadrenocorticism and decide to run an ACTH stim test. The results from the 1-hour cortisol is <2ug/dL. What is your interpretation?
This result is consistent with HOC
190
A patient presents to you and you aren't entirely sure if the patient has hypoadrenocorticism or something else. What test should you run?
Baseline cortisol
191
A patient presents to you and HOC is your top differential based on exam findings and clinical signs. What test should you do to confirm?
ACTH stimulation test
192
What are the treatment recommendations for patients experiencing an Addisonian crisis?
IV fluid therapy & electrolyte correction (if life threatening), ACTH stim test, corticosteroid replacement (often Dexamethosone), mineralocorticoid replacement (DOCP aka Percorten)
193
What are the treatment recommendations for patients with stable HOC?
Resting cortisol -> ACTH stim test, corticosteroid replacement (Prednisone), mineralocorticoid replacement (DOCP aka Percorten injection given every 25-28 days)
