Endocrinology Flashcards
1
Q
Which two types of hormones are modified amino acids?
A
Catecholamines (dopamine, epi, norepi)
Thyroid
2
Q
How do peptide hormones exert effects on target tissues?
A
Binding to surface receptors which trigger intracellular 2nd messenger
3
Q
Steroid hormones are derived from which molecule
A
Cholesterol
4
Q
What two general hormone types are lipid soluble? How are they transported in blood?
A
Thyroid and steroid
Transported bound to proteins
5
Q
Which protein binds to iodine within thyroid colloid?
A
Thyroglobulin
6
Q
Which thyroid hormone has a shorter half life?
A
T3
7
Q
Which thyroid hormone is metabolically active?
A
T3
8
Q
Which thyroid hormone has the shortest latency period and quickest to reach maximum cellular activity?
A
T3
9
Q
How does thyroid hormone affect systemic vascular resistance?
A
Reduces it (vasodilation)
10
Q
Which thyroid hormone is most substantially affected by nonthyroidal illness?
A
TT4
11
Q
What are the three forms of calcium?
A
iCa (50%), protein-bound (40%), complexed with anions (10%
12
Q
Which receptor is responsible for detecting changes in calcium levels?
A
CaSR (present in parathyroid, kidney, bone)
13
Q
Which hormone is secreted in response to hypocalcemia?
A
PTH
14
Q
Name 3 effects of PTH on the kidney
A
Increases Ca++ reabsorption
Decreases PO4 reabsorption
Increases vitamin D activation
15
Q
Name 3 negative regulators of PTH secretion
A
Hyperalcemia
Vitamin D
FGF23
16
Q
Which hormone is secreted in response to hypercalcemia?
A
Calcitonin
17
Q
Which two organs are involved in activation of vitamin D?
A
Liver and kidney
18
Q
Which enzyme controls formation of active vitamin D in the kidney?
A
Alpha-1-hydroxylase
19
Q
Name two effects of vitamin D on the intestines?
A
Increase Ca absorption
Increase PO4 absorption
20
Q
Which hormone is the master regulator of blood PO4 levels?
A
FGF23 (induces phosphaturia and decreases intestinal phosphate absorption via inhibition of VitD)
21
Q
What is the strongest stimulus for aldosterone secretion?
A
Hyperkalemia
22
Q
What are the layers of the adrenal cortex, from outside to inside
A
Glomerulosa (mineralocorticoids)
Fasciculata (glucocorticoids)
Reticularis (sex hormones)
23
Q
Where in the kidney does aldosterone exert its effects?
A
Distal tubule (increases renal reabsorption of Na/H2O, increases excretion of K+)
24
Q
Which hormones inhibit aldosterone
A
ANP/BNP
25
Which of the following is not an effect of glucocorticoids:
A) Increased insulin sensitivity
B) Increased lipolysis
C) Increased gluconeogenesis
D) Increased beta-oxidation
A (decreases peripheral insulin sensitivity)
26
Which enzyme is responsible for the first step in steroidogenesis (e.g., conversion of cholesterol to pregnenolone)
Cholesterol desmolase (CYP11A1)
27
Which catecholamine is produced in greater quantities from the adrenal medulla?
Epinephrine (80%) > NE (20%)
28
Which cells in the adrenal medulla produce catecholamines?
Chromaffin cells
29
What is the major transport protein for glucocorticoids?
Corticoid binding globulin (CBG)
30
Which cells in the endocrine pancreas produce glucagon?
Alpha cells
31
Which cells in the endocrine pancreas produce somatostatin?
Delta cells
32
Cleavage of pro-insulin produces insulin and which molecule?
Peptide C
33
Which enzyme senses circulating glucose levels on beta cells?
Glucokinase
34
Name 3 stimuli of insulin secretion
Increased blood glucose
GLP-1/GIP (incretins)
Parasympathetic stimulation
35
Name 2 inhibitors of insulin secretion
Somatostatin
Decreased blood glucose
Sympathetic stimulation (alpha-adrenergic)
Leptin
36
Insulin stimulates translocation of ____ which increases cellular permeability to glucose
GLUT4
37
Name two effects of insulin on the liver
Promotion of glycogen synthesis (via glycogen synthase)
Inhibition of glycogenolysis (via inhibition of glycogen phosphorylase)
38
Which enzyme in adipose tissue is activated by insulin?
Lipoprotein lipase (LPL)- promotes fatty acid uptake/storage
39
Which enzyme in adipose tissue is activated by glucagon?
Hormone sensitive lipase (HSL)- promotes lipolysis
40
Which hormone inhibits both insulin and glucagon?
Somatostatin
41
Which nuclei (2) synthesize ADH/oxytocin?
Supraoptic
Paraventricular
42
Where are plasma osmoreceptors located?
Circumventricular organs
43
Name 3 stimuli for ADH release
Angiotensin II
Hypotension
Increased serum osmolarity
44
Which receptor does ADH bind to in the collecting duct?
V2 (triggers increased AQP2 expression)
45
5 cells types in the anterior pituitary
Lactotrophs
Gonadotrophs
Thyrotrophs
Corticotrophs
Somatotrophs
46
What is the precursor molecule for ACTH?
POMC
47
In addition to ACTH, which molecules are produced through cleavage of POMC (3)?
Alpha-MSH
B-endorphin
CLIP
48
Which cells produce POMC in the pars intermedia?
Melanotrophs
49
Which hypothalamic hormone is also known as somatostatin?
GHIH
50
Adipose tissue secretes hormones called ______
Adipokines
51
What is the primary effect of leptin?
Controls appetite and regulates energy expenditure
52
Which adipose hormone exerts anti-inflammatory effects and increases insulin sensitivity?
Adiponectin
53
Which adipose hormone contributes to adipocyte necrosis?
TNF-alpha
54
What type of histopathologic change is responsible for the majority of feline hyperthyroidism cases?
Adenoma/hyperplasia
55
What is the mechanism of PU/PD in hyperthyroidism?
Increased GFR and renal medullary washout
56
Name 2 sequelae of hyperthyroidism
Systemic hypertension (30%)
Myocardial changes/heart murmur
57
CBC finding expected with hyperthyroidism
Erythrocytosis (40-50% of cases)
58
Most common chemistry finding with feline hyperthyroidism
ALT elevation (80%)
59
What is the best screening test for feline hyperthyroidism?
TT4
60
What would you expect to see in a T3 suppression test in a hyperthyroid cat?
No suppression
61
What is the gold standard diagnostic for feline hyperthyroidism?
Thyroid scintigraphy
62
What is the mechanism of action of methimazole?
Thyroid peroxidase inhibitor
63
What is the pro-drug of methimazole?
Carbimazole
64
What is the most common cause of hypothyroidism in dogs?
Lymphocytic thyroiditis/thyroid atrophy
65
What % of dogs with gallbladder mucocele are hypothyroid?
25%
66
Name 3 drugs which decrease thyroid hormones?
Steroids
Phenobarbital
Palladia
67
What is the most common chemistry finding in hypothyroid dogs?
Hypercholesterolemia (75%)
68
Hypothyroidism is associated with resistance to which adipose hormone?
Adiponectin
69
A dog with clinical signs consistent with hypothyroidism. TT4 is high and TSH is high. What is the most likely explanation?
Lymphocytic thyroiditis (autoantibody interference). Likely positive TgAA
70
When should TT4 levels be measured when assessing efficacy of levothyroxine therapy?
4-6 hours post-pill
71
What is the mechanism of hypoglycemia in hypoadrenocorticism?
Decreased glucocorticoids lead to increased insulin sensitivity/peripheral utilization of glucose and decreased gluconeogenesis
72
What is the mechanism of PU/PD in hypoadrenocorticism?
Hyponatremia impairs secretion of ADH and leads to washout of renal medullary gradient
73
Name three differentials for hyponatremia, hypochloremia, and hyperkalemia
Hypoadrenocorticism
Whipworm infection
DKA
74
Calcium levels are usually ____ with hypoadrenocortcism
Increased
75
Which test is used to diagnose hypoadrenocorticism?
ACTH stim
76
Which exogenous mineralocorticoid is preferred for the treatment of hypoadrenocorticism?
DOCP (Percorten/Zycortel)
77
Which form of hyperadrenocorticism is more common (pituitary or adrenal-dependent)?
PDH (80-85% of cases)
78
What is the mechanism of PU/PD in hyperadrenocorticism?
Defective release/action of ADH on renal tubules (NDI) vs CDI from large pituitary tumor
79
Name 3 complications of hyperadrenocorticism
Systemic hypertension
Insulin-resistance (DM)
Gallbladder mucocele
CHF
PTE
Calcium oxalate uroliths
80
How does hyperadrenocorticism contribute to systemic hypertension (3 mechanisms)
RAAS activation
Enhanced sensitivity to vasopressors
Increased Na+ retention
81
Which urinalysis finding is a common consequence of systemic hypertension associated with hyperadrenocorticism?
Mild to moderate proteinuria
82
Name 3 screening tests for hyperadrenocorticism
UCCR
ACTH stim
LDDST (test of choice)
83
Which test can be used to both screen and differentiate between forms of hyperadrenocorticism?
LDDST
84
An escape pattern on LDDST is suggestive of which form of hyperadrenocorticism?
PDH
Suppression at 4 hours but lack of suppression at 8 hours
85
Name two tests which can be used to differentiate between PDH/ADH
eACTH
HDDST
86
Which medical therapy is preferred for adrenal-dependent hyperadrenocorticism caused by an adrenal tumor?
Mitotane
87
What is the mechanism of action of mitotane?
Potent adrenocorticolytic
Inhibits multiple enzymes involved in synthesis of adrenal tumors
88
What is the mechanism of action of trilostane?
Inhibits 3B-HSD (predominantly affects glucocorticoid synthesis)
89
What is the mechanism of action of cabergoline?
Dopamine agonist, binds to DRD2 receptor in canine corticotroph adenomas (pro-apoptotic, anti-proliferative)
90
What is the mechanism of action of octreotide?
SST analog which inhibits ACTH release by corticotrophs
91
Skin fragility is a common clinical sign associated with which endocrinopathy in cats?
Hyperadrenocorticism
92
What is the most common feline adrenocortical disorder?
Hyperaldosteronism
93
Name 2 sequelae of hyperaldosteronism in cats
Hypertension
Severe hypokalemia (leading to weakness, cervical ventroflexion)
94
Diagnosis of hyperaldosteronism
Plasma aldosterone:renin ratio
95
Medication used to treat hyperaldosteronism
Spironolactone (aldosterone receptor blocker)
96
Epinephrine/norepinephrine are metabolized to _____
Metanephrines
97
Which medication is used to medically manage pheochromocytomas?
Phenoxybenzamine (alpha blocker)
98
In addition to insulinoma, what tumor type can lead to a hyperinsulinemic syndrome?
Hepatocellular carcinoma
99
What is the mechanism of action and clinical utility of steptozocin?
Nitrosurea antibiotic which selectively destroys beta cells. Used to manage insulinomas
100
What is the mechanism of action and clinical utility of diazoxide?
Inhibits closure of pancreatic beta cell ATP-dependent K+ channels, preventing release of insulin
101
Diabetic cat in remission. Which of the following will help to maintain remission?
A) Initiation of exogenous steroids
B) Increasing dietary carbohydrate intake
C) Weight loss
C
102
Cat presents with PU/PD/PP, weight loss. Spot BG 300mg/dL. Which test should you perform next?
Fructosamine (or have owner collect multiple urine samples to assess for glucosuria)
103
Which insulins are 40u/mL? (2)
Caninsinulin
PZI
104
Which insulin is typically the go-to for a newly diagnosed, uncomplicated diabetic dog?
Caninsulin
105
Why is glargine insulin long-acting?
Forms precipitates in the SQ which delay absorption, leading to peakless profile
106
Why is Levemir (Detemir) insulin long-acting?
Reversibly binds to albumin
107
Why is PZI long-acting?
Formation of zinc/insulin/ protamine complexes which precipitate at neutral pH and slow absorption
108
Which insulin is very potent in dogs and should be used with caution?
Detemir (Levemir)
109
Name 3 classes of oral hypoglycemics
GLP-1 agonists
SGLT-2 antagonists
Sulfonylureas
Acarbose
110
Name two types of glycated proteins
Fructosamine (BG over 1-2 weeks)
Hemoglobin A1c (BG over 2-3 months)
111
Name 3 factors which can artificially decrease fructosamine levels
Hypoproteinemia
Hemolysis
Hyperthyroidism
Azotemia
112
T/F: hemolysis will artificially increase hemoglobin A1c levels
False- unaffected by hemolysis
113
Ideal BG nadir with insulin therapy
80-150mg/dL
114
Name 3 explanations for persistent hyperglycemia in a diabetic
Technical issues
Concurrent disease
Incorrect insulin type/frequency/dose
115
Type of neuropathy seen in diabetic cats
Axonal preodminantly
116
Why might a well-controlled DM dog present in DKA?
Development of concurrent disease (e.g., pancreatitis, Cushing's, UTI)
117
Which condition is commonly associated with poor DM control in cats?
Acromegaly (hypersomatotropism)
118
Broad facial features, HCM, and CNS signs in a diabetic cat should prompt suspicion of which condition
Acromegaly (hypersomatotropism)
119
Keeshond presenting with hypercalcemia. Calcium panel showed high PTH, high iCa, low PO4, normal vitamin D. Diagnosis?
Primary hyperparathyroidism
120
Name 3 treatments for acute hypercalcemia
0.9% NaCl diuresis
Furosemide
Steroids
121
Name 4 causes of hypocalcemia
Hypoproteinemia (PLE)
CKD (decreased vitamin D production)
Acute pancreatitis
Ethylene glycol toxicity
Hypoparathyroidism
Puerperal tetany
Transfusions (EDTA/citrate)
122
Name 2 causes of secondary nephrogenic diabetes insipidus
Hyperadrenocorticism
Pyometra
123
Young dog presents with marked PU/PD and USG 1.004. What is the next diagnostic step?
MWDT
124
Old St Bernard presenting with low basal cortisol, low eACTH, and low ACTH stim. What is the most likely diagnosis?
Secondary hypoadrenocorticism
125
Which electrolyte abnormality can result in hemolysis following treatment of DKA?
Hypophosphatemia
126
Which diet is ideal for cats with DM?
High protein, low carb
127
Low dose dexamethasone suppression test: Which of the following is the most likely diagnosis? Normal = <2 ug/dL
Baseline cortisol – 10 ug/dL
4 hr post stim – 6 ug/dL
8 hour post stim – 6 ug/dL
Hyperadrenocorticism (cannot distinguish PDH vs ADH)
128
Which of the following is released from the anterior pituitary?
A) Somatostatin
B) Prolactin
C) Oxytocin
D) ADH
B
129
Cat presents with extreme lethargy, weight loss, BG 350mg/dL, ketoacidosis. What is the first treatment that should be implemented?
IV fluids
130
What is the typical presentation for canine hypoadrenocorticism?
Chronic, vague GI signs
131
Which electrolyte abnormality can cause secondary NDI?
Hypokalemia
