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Endocrine Flashcards

1
Q

What cells are pheochromocytoma derived from?

A

Chromaffin cells of the adrenal medulla.
Chromaffin cells also called APUD cells → responsible for amine precursor uptake and decarboxylation

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2
Q

What are the clinical signs of pheochromocytoma?

A

Systemic hypertension, weakness, collapse, lethargy, v/d, PUPD, tachypnea, abdominal distention, syncope, tachyarrhythmias, bradyarrhythmias, abdominal pain
* sustained or paroxysmal

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3
Q

True or False: High concentration of urinary normetanephrine was highly suggestive of pheochromocytoma.

A

True
* Urinary normetanephrine-to- creatinine ratio proved to be superior to epinephrine-, norepinephrine-, or metanephrine-to-creatinine ratios

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4
Q

In human, what drug can be given to reverse the catecholamine-induced vasoconstriction from pheochromocytoma?

A

Phentolamine, an reversible non-selective α-adrenergic antagonist

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5
Q

What drugs should be avoided in pheochromocytoma patients due to possible acute hypertensive crisis?

A

Metoclopramide***, histamine, tyramine, glucagon

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6
Q

What are the pre-, peri-, and post- anesthetic management for pheochromocytoma?

A

Pre:
1) start non-competitive α-adrenergic blockade with phenoxybenzamine (0.5 to 2.5 mg/kg PO q12h) 1 week before sx
2) blood type

Peri:
1) opioid + bzd + propofol for premed and induction
2) avoid halothane → sensitizes the myocardium to catecholamine- induced arrhythmias
3) monitor ECG and blood pressure
4) prepare esmolol (0.05 to 0.5 mg/kg IV followed by 10 to 200 mcg/kg/min IV), vasodilators such as nitroprusside (0.5 to 5 mcg/kg/min IV) or magnesium sulfate
5) prepare phenylephrine (0.5 to 5 mcg/kg/min IV) or norepinephrine (0.1 to 2 mcg/kg/ min IV) because patient may become hypotensive after tumor removal

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7
Q

What is the medical management for pheochromocytoma?

A

Phenoxybenzamine, β-blockers, and/or other anti-arrhythmic agents
* β-Blockers should not be given without concurrent α-blockade → loss of β2 receptor–mediated vasodilation may exacerbate hypertension

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8
Q

What is Budd-Chiari-like syndrome?

A

Mechanical obstruction of the hepatic venous outflow → liver congestion, right upper quadrant pain, ascites

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9
Q

For pheochromocytoma, what is the negative prognostic indicators for surgical outcome?

A

Vena cava invasion, older age, intra-op arrhythmias, prolonged surgical time

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10
Q

How are NE and Epi synthesized?

A

Tyrosine enters the nerve → DOPA → Dopamine → enters the vesicles → NE → exits the vesicle and receives a methyl group → Epi → re-enters the vesicles

Resources: https://cvpharmacology.com/norepinephrine

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11
Q

How are NE and Epi metabolized?

A

1) Neuronal re-uptake
2) Catechol-o-methyltransferase (COMT) and monoamine oxidase(MAO)

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12
Q

How is the ketone body synthesized?

A

Fatty acids went through 𝜷-oxidation and form Acetyl-CoA.

Normal situation: Glucose degraded into pyruvate → both Acetyl-CoA and pyruvate enter TCA cycles

Diabetic: No pyruvate; two Acetyl-CoA → form ketone bodies

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13
Q

What are three types of ketone bodies?

A

Acetoacetate (strong acid)
𝜷-hydroxybutyrate (strong acid)
acetone

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14
Q

Which ketone body cannot be detected by the urine strip test (nitroprusside reaction)?

A

𝜷-hydroxybutyrate

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15
Q

Why occasionally there will be negative urine ketone on day 1 but became positive on day 2 or 3 after the treatment is started?

A

After starting the insulin treatment, the urine 𝜷-hydroxybutyrate : Acetoacetate ratio may decrease because more 𝜷-hydroxybutyrate is metabolized back to acetoacetate and therefore can be detected with nitroprusside test

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16
Q

What are the most common concurrent diseases in dogs with DKA?

A

Acute pancreatitis
Bacterial UTI
Hyperadrenocorticism

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17
Q

What are the most common concurrent diseases in cats with DKA?

A

Hepatic lipidosis
CKD
Acute pancreatitis
Bacterial/viral infection
Neoplasia

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18
Q

What is the concentrations of K and Phos in Kphos?

A

K: 4.4 mEq/ml
Phos: 3 mM/ml

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19
Q

What is the rate to supply phos in patient with DKA and hypophoshpatemia?

A

0.03 - 0.12 mM/kg/hr

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20
Q

Describe the CRI regular insulin protocol for DKA.

A
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21
Q

What is the recommendation from The American Diabetes Association for bicarb supplementation for pediatric DKA patients?

A

1) Who should be treated?
who maintain a pH < 7.0 after 1 hour of fluid therapy

2) How to treat it?
Sodium bicarb 2 mEq/kg added to 0.9% NaCl, in a solution that does not exceed 155 mEq/L of sodium, over 1 hour.

3) How to monitor?
The pH is monitored q1h and treatment is repeated until pH ≥ 7.0

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22
Q

What is the hallmarks for HHS?

A
  1. BG > 600 mg/dL
  2. Minimal or negative urine ketone
  3. Serum osmolarity > 350 mOsm/kg (cat) or 325 mOsm/kg (dog)
  4. Ketotic vs non-ketotic
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23
Q

Describe the pathogenesis of HHS.

A

1) Hormone alteration
Insulin deficiency + increased countercurrent hormone (e.g. epinephrine, glucagon, cortisol, growth hormone)
- Epinephrine & glucagon inhibit insulin-mediated glucose uptake in muscle and stimulate hepatic glycogenolysis and gluconeogenesis
- Cortisol & growth hormone inhibit insulin activity and potentiate the effects of glucagon and epinephrine

2) Decrease GFR

3) Presence of concurrent disease
- CKD, CHF, pancreatitis (dog), neoplasia, other endocrinopathies

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24
Q

What is the main difference between HHS and DKA?

A

HHS usually has higher BG level and higher osmolarity. Patients with HHS also have higher circulating insulin level and lower glucagon level → this inhibits the liver to perform lipolysis due to presence of insulin.

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25
What is the equation of serum osmolality?
Serum osmolality (mOsm) = 2 x Na + BUN/2.8 + BG/18 * Unit for Na = mEq/L * Unit for BUN & BG = mg/dL
26
What is the equation of effective osmolality
Effective osmolality (mOsm) = 2 x Na + BG/18
27
What are the main contributors for metabolic acidosis in DKA and HHS, respectively?
DKA: ketones HHS: uremic acids, lactic acids
28
What is the equation to correct Na in HHS patient?
Corrected Na = Patient's Na + 1.6 x [(Measured BG - Normal BG)/100] * Unit for Na = mEq/L * Unit for BG = mg/dL
29
True of False: For HHS management, using IM or IV protocols of regular insulin at dosages 50% of those used for DKA should reduce the risk of a too rapid decline of serum glucose.
True
30
What is the target rate to reduce BG in HHS patients?
No more than 50-75 mg/dL/hr
31
True or False: Many dogs with HHS has recent steroid administration
True (18%) * In the same study, poor outcome was associated with abnormal mentation and low venous pH Reference: Trotman TK, Drobatz KJ, Hess RS. Retrospective evaluation of hyperosmolar hyperglycemia in 66 dogs (1993-2008). J Vet Emerg Crit Care (San Antonio). 2013;23(5):557-564.
32
How is potassium affected in patients with DKA/HHS?
1) Acidosis → K+ is shifted out of the cell in exchange with H+ 2) Decreased dietary intake → K ↓ 3) Hypovolemia induced hyperaldosteronism → increased renal loss 4) Insulin deficiency → decreases the amount of K co-transported into cells 5) Decreased GFR → K accumulates in the blood
33
True or False: The BG level in the brain is the same as plasma.
False Glucose concentrations in the brain are up to 30% lower compared to plasma
34
What is the cutoff to diagnose insulinoma with insulin:glucose ratio?
> 30 is supportive of insulinoma * Equation: AIGR = (insulin × 100) ÷ (plasma glucose − 30) * Need to collect the blood when BG < 60
35
What is the formula to correct point-of-care BG based on PCV?
Corrected POC BG = Measured POC BG + [(1.6 x PCV) - 81.3] Reference: Lane SL, Koenig A, Brainard BM. Formulation and validation of a predictive model to correct blood glucose concentrations obtained with a veterinary point-of-care glucometer in hemodiluted and hemoconcentrated canine blood samples. J Am Vet Med Assoc. 2015;246(3):307-312.
36
Where is the glucagon from? Where does it work?
1) 𝜶 cells in the pancreas 2) liver, promote glycogenolysis and gluconeogenesis
37
How does 𝜷-blocker cause hypoglycemia?
interference with adrenergic counterregulatory mechanisms **bad question - it usually cause hyperglycemia
38
When should you raise a concern for insulin resistance?
when insulin dose > 1.5U/kg q12h
39
What are the four factors contributing to thyroid storm in cats?
1) Higher concentration of circulating thyroid hormone 2) Acute, rapid increase of circulating thyroid hormone 3) Hyperactivity of the sympathetic nerve system 4) Increased cellular response to thyroid hormone
40
What is the axis stimulating thyroid synthesis?
TRH from hypothalamus → TSH from Anterior pituitary gland → thyroid gland
41
What are the differences between T3 and T4?
T4 (thyroxine) - 93% of the thyroid hormone released from the gland - When enters the cells, one iodide was removed and most of T4 are converted to T3 T3 (triiodothyronine) - 7% of the thyroid hormone released from the gland - biologically active form - Has much higher affinity to the intracellular receptors for nucleus transcription
42
List 5 precipitating events for feline thyroid storm.
Stress Vigorous palpation of the thyroid Thyroidal or parathyroidal surgery Radioactive iodine therapy Sudden withdrawal of the methimazole Administration of iodinated contrast dyes Administration of stable iodine compounds Nonthyroidal illness (e.g. infection) Amiodarone therapy
43
Is T4 and T3 highly protein bound? What are the protein they bind to?
Yes both are highly protein-bound About 60% is bound to thyroxine binding globulin, 17% to transthyretin, 12% to albumin and 11% to various lipoprotein fractions. Only about 0.3 - 1% are free form (active form)
44
What is the MOA for methimazole?
Methimazole inhibits the action of thyroid peroxidase → inhibits the incorporation of iodide into thyroglobulin → decrease T4 & T3 production Dose: 5mg per cat q12h
45
What are the medical treatments to decrease thyroid hormone production/secretion for suspect thyroid storm?
1) methimazole (cannot stop the release of stored thyroid hormone) 2) potassium iodide (stable iodine compounds) - Prevent secretion of thyroid hormone - Need to give 1 hr after methimazole administration - 25mg PO q8h 3) iopanoic acid (lipid-soluble radiographic contrast agent) - Prevent secretion of thyroid hormone - block peripheral conversion of T4 to T3 - block T3 from binding to its receptor - inhibit thyroid hormone synthesis - 100mg per cat PO q12h 4) Dexamethasone - inhibit peripheral conversion of T4 into T3 - 0.1-0.2 mg/kg PO/IV
46
Why illness can cause decreased thyroid hormone production?
Illness can increase plasma glucocorticoid concentration → inhibit TSH secretion from anterior pituitary gland
47
What are the pros and cons for each beta blockers for treating feline thyroid storm?
Propranolol - Pros: can inhibit peripheral T4 conversion to T3 (slow) - Cons: poor oral bioavailability, short half-life (need TID) - 5mg PO q8h Atenolol - Pros: better oral bioavailability and SID administration - Cons: doesn't affect the T4 conversion - 1 mg/kg PO q12h-q24h Esmolol - very short acting - 0.1-0.5 mg/kg IV, followed with CRI 10-200 mcg/kg/min
48
What are the clinical signs in cats with feline thyroid storm (organ system)?
Fever GI system CNS Cardiovascular system Hypercoagulable state
49
Which breed is predisposed to hypothyroid crisis?
Rottweiler
50
What are the 6 classic hallmark for hypothyroid crisis?
myxedema (accumulation of glycosaminoglycan hyaluronic acid) in the dermis coma hypothermia bradycardia hypoventilation hypotension
51
What are the risk factors of developing hypothyroid crisis?
Infection (e.g. pneumonia) NSAIDs or glucocorticoid use Surgery Others in humans: burns, CO2 retention, GI hemorrhage, hypoglycemia, infection, hypothermia (most cases are diagnosed during the winter), stroke, trauma, and various medications, including anesthetics, barbiturates, β-blockers, diuretics, narcotics, phenothiazines, and tranquilizers.
52
What are the six hormones that the anterior pituitary gland produces? What are the two hormones that the posterior pituitary gland produces?
Anterior glands ACTH (Adrenocorticotrophic hormone) TSH (Thyroid-stimulating hormone) Growth hormone (GH) Follicle-stimulating hormone (FSH) Luteinizing hormone (LH) Prolactin Posterior glands Oxytocin Vasopressin * These hormones are synthesized in the hypothalamus and stored in the posterior pituitary gland
53
List the 4 stimulating hormones and 2 inhibitory hormones released by the hypothalamus.
54
Describe the anatomic compositions of adrenal glands and the hormones each part secretes
From outside to inside: Cortex - Glomerulosa: Aldosterone (minerocorticoid) - Fasciculata: Glucocorticoid - Reticularis: sex hormones Medulla: catecholamine
55
What are the protein-binding and half life of minerocorticoid and cortisol, respectively?
Cortisol: highly protein bound (~ 90%), 60-90 min Minerocorticoid: 60% protein bound, 20 min
56
True or False: Besides glucocorticoid, ACTH can also stimulate minerocorticoid release.
True (to a lesser extent)
57
What is the original source of all the adrenal hormone?
Cholesterol
58
In the synthesis of adrenal hormones, which step is the rate limiting step?
Conversion of cholesterol to pregnenolone
59
Describe the function of aldosterone
- Mainly works at the collecting duct - Account for 5-10% Na absorption - At the principle cells - Increases number of epithelial Na channels (ENaC) and Na-K ATPase → increase Na and water resorption and K excretion - At the intercalated cells - Increases H ion pump → increases H secretion in exchange with Na - At the colon - Increases Na resorption (small amount)
60
According to a multicenter study published by Hauck and colleagues in 2020, what is the prevalence of hypoadrenocorticism in dogs with chronic GI signs?
4% (6/151) Reference: Hauck C, Schmitz SS, Burgener IA, et al. Prevalence and characterization of hypoadrenocorticism in dogs with signs of chronic gastrointestinal disease: A multicenter study. J Vet Intern Med. 2020;34(4):1399-1405.
61
Name 5 drugs that can cause iatrogenic hypoadrenocorticism.
Trilostane Ketoconazole Mitotane Phenobarbital Etomidate
62
What is the characteristics of stress leukogram
Neutrophilia Lymphopenia Eosinopenia +/- Monocytosis
63
List 5 pseudo-Addison's diseases.
Severe GI diseases Heavy GI parasites (whipworms) Kidney diseases Pregnancy Body cavity effusion CHF
64
What is the full name for DOCP and the starting dose?
Deoxycorticosterone pivalate 2.2 mg/kg SC or IM
65
Why do dogs with Addison's disease hypoglycemic?
Cortisol facilitates glycogenolysis and gluconeogenesis → lack of cortisol may lead to decrease glucose production
66
Why patients with Addison's disease can have low USG despite severely dehydration?
medullary washout secondary to hyponatremia
67
What are the possible complications from sodium bicarb administration?
1) Hypokalemia 2) Hemolysis from hyperosmolality 3) Paradoxical intracellular acidosis 4) Hypernatremia 5) Decreased ionized calcium level → decreased ventricular contractiliy Increase pH → increased binding of Ca to albumin 6) Shifting the oxygen-hemoglobin association curve to the left (Bohr effect) → increases binding → decrease O2 delivery 7) Hypervolemia
68
True or False: Dexamethasone has both minerocorticoid and glucocorticoid effect
False Dexamethasone only has glucocorticoid effect
69
Write down the different steroid, their minerocorticoid and glucocorticoid effects, plasma half life, and biological half-life.
70
What are the differences in results between French study and CORTICUS study?
1) French study (n=300): for non-responders to cortioctropin test, those received hydrocortisone (50mg IV q6h for 7 days) and fludrocortisone (50mg PO SID) had lower mortality rate and higher percentage of pressor withdrawal rate 2) CORTICUS study (n=499): patients (both responders and non-responders) received hydrocortisone (50mg IV q6h for 6 days) doesn't have different mortality rate than the placebo group. In the hydrocortisone group, shock was reversed more rapidly but patients had more episodes of superinfection or new sepsis.
71
True or False: The 2013 Surviving Sepsis Campaign recommends patients with suspected CIRCI should be confirmed with ACTH stimulation test before starting the treatment.
False The 2013 Surviving Sepsis Campaign guidelines suggest NOT using ACTH stimulation testing to identify which patients should be treated with hydrocortisone.
72
What are the proposed pathophysiology of CIRCI?
1) inflammation, infarct, hemorrhage or iatrogenic cause of adrenal gland insufficiency 2) systemic inflammation leads to decreased corticosteroid-binding globulin (CBG) production 3) cytokines lead to dysregulated intracellular glucocorticoid receptors (e.g. inhibits binding & gene transcription) & enzymes
73
What are the common PE and clinical pathological findings for primary hyperaldosteronism?
Systemic hypertension, hypokalemia *patients usually don't have hypernatremia due to concurrent water retention and dilution (total body sodium does increase)
74
Fill out the blank
75
How many parathyroid glands do dogs and cats have?
4 glands (two on each side)
76
What can stimulate PTH production? What can inhibit PTH production?
Stimulation: low ionized Ca level, high phos level, acidosis, catecholamines, prostaglandin E2 Inhibition: high ionized Ca level, calcitriol, FGF-23, very high Mg
77
What can stimulate calcitriol production? What can inhibit calcitriol production?
Stimulation: low ionized Ca level, low phosphorus level, PTH, low Ca diet, estrogen, testosterone Inhibition: high ionized Ca level, high phosphorus level, FGF-23, calcitriol
78
Describe the calcium distribution.
99% in the bone as hydroxyapatite For the remaining 1% about 55% as ionized calcium, 35% protein-bound and the remaining 10% complexed with other electrolytes (e.g. phosphate, bicarb, magnesium, citrate, lactate)
79
Describe the phosphorus distribution.
85% in the bone as hydroxyapatite, 15% in soft tissue (e.g. muscles), less than 1% in the ECF For those in ECF: 2/3 are organic form (e.g. phospholipid) 1/3 are inorganic form (what we measured) 85% H2PO4- and HPO42- 10% Protein-bound 5% Complexed with calcium and magnesium
80
True or False: PTH only secretes when the ionized calcium is low.
False PTH is constantly secreted from the parathyroid gland. It has very short half-life (3-5 min).
81
How much percentage drop of iCa can elicit max PTH secretion?
10%
82
True or False: PTHrP functions as calcium-regulating hormone in fetus and is produced from placenta.
True
83
What are the three endocrines secreted from the pancreas?
Insulin - facilitate glucose uptake by the cells, glycogen synthesis, lipid and protein storage Glucagon - glycogenolysis, gluconeogenesis Somatostatin - inhibits the secretion of other pancreatic hormones such as insulin and glucagon
84
What do you need to monitor and supply in dogs with post-op parathyroidectomy?
Monitor total Ca and iCa twice daily If patient shows clinical signs of hypocalcemia (e.g. tetany) - supply 10% Calcium gluconate 0.5-1 ml/kg slow IV over 15 minutes Start calcitriol supplementation 0.02-0.03 ng/kg/d (divided into BID) for 2-4 days, and then taper to 0.005 - 0.015 ng/kg/d (divided into BID) Slowly prolong the duration and recheck biweekly May take 3-6 months to withdrawal
85
Describe aldosterone paradox
Aldosterone usually increases in response to hypovolemia and hyperkalemia. In patients with hypovolemia, aldosterone will facilitate Na and water retention, but the K+ secretion remains unchanged. In patients with hyperkalemia, aldosterone will facilitates K+ secretion but does not affect the Na+ resorption rate. It is proposed that the main difference lies in the presence of angiotensin II. RAAS will be activated during the state of hypovolemia but not for hyperkalemia.
86
What are the 2 most common locations for intestinal intussuseption?
Enterocolic (ileocecocolic) enteroenteric (jejunum)
87
How much of the small intestine can be removed in dogs and cats without developing short bowel syndrome?
50%
88
Which hormone increases the prolactin production and which hormone inhibit it?
Increase: estrogen Decrease: dopamine
89
What are the 4 types of vasopressin receptors and what are their functions?
V1- vascular smooth muscle V2 - renal collecting duct, platelet, endothelium, vascular endothelium V3- pituitary gland Oxytocin - uterus, GI tract, mammary gland * Platelet also has V1R → facilitates thrombosis by increasing in intracellular Ca * V3R also is responsible for all the CNS effect (e.g. temperature regulation, sleep)
90
List 5 things that can cause vasopressin release besides increased plasma osmolality and a decrease in circulating blood volume.
1) Pain 2) Nausea 3) Hypoxemia 4) Hypercapnea 5) Pharyngeal stimuli 6) Mechanical ventilation 7) Glycopenia 8) Angiotensin II 9) High dose opioid 10) Acetylcholine 11) Histamine 12) Glutamine 13) Prostaglandins 14) dopamine
91
How does glucocorticoid affect vasopressin?
It inhibits vasopressin release.
92
How does the body detect change in osmolality and induce vasopressin release? Where are the osmoreceptors?
Central receptor: in the third ventricle Peripheral receptor: in the mesenteric and portal veins
93
What are the two pathways of vasopressin causing vasoconstriction?
1) Gq protein-coupled receptors → activate the phospholipase C and phosphoinositide pathways → activate voltage-gated calcium channels 2) Inactivation of K-ATP channels in the vascular smooth muscle cells → facilitate depolarization → opening of Ca channels
94
What type of receptor is V2 receptors?
Gs protein-coupled receptors (→ increases intracellular cAMP → aquaporin-2 pop up at the luminal side)
95
Which V receptor does DDAVP bind to? What
V2R * So DDAVP can also cause vasodilation at afferent arterioles
96
How is vasopressin metabolized? What is it protein-binding?
NO protein-binding Renal excretion (65%) and metabolism by tissue peptidases (35%)
97
What is the MOA of hyperadrenocorticism-induced hypertension?
Glucocorticoids induce hepatic production of angiotensinogen → exaggerated response of the renin-angiotensin system
98
What is Budd-Chiari-like syndrome?
Mechanical obstruction of the hepatic venous outflow → liver congestion, right upper quadrant pain, ascites

Boards: Endocrine (11 decks)

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