120. Adrenal Glands

Question 1

general indications to perform adrenalectomy

Answer 1

—characteristics of malignancy—functional tumors

Question 2

adrenal gland vasculature

Answer 2

phrenicoabdominal artery (also branches from renal and cranial abdominal vasculature)single adrenal veinLeft—associated with aorta wall (L2)Right—associated with cd vena cava (13th rib)

Question 3

architecture and functional zones of adrenal gland

Answer 3

CORTEXz. glomerulosa (salt)–aldosterone (MCC), fluid/electrolyte balance; LACK 17 alpha hydroxylasez. fasiculata (sugar)–cortisol (GCC), stress adaptation/CHO metabolismz. reticularis (sex)- sex steroids (small amount)MEDULLA–chromaffin cellscatecholamines made from tyrosine –epinephrine (80%)–norepinephrine (20%)sympathetic nerve stimulation (alpha and beta adrenergic receptors)

Question 4

actions of epinephrine and norepinephrine release

Answer 4

—EPI (80%) NE (20%)–epi 10x more potent than NE on Beta 2–on beta 1: ionotropic and chronotropic; increase renin (RAAS)–on beta 2: stimulates gluconeogenesis and glycogenolysis, inhibits insulin (all to increase glucose); also can cause vasodilation in skeletal muscle; smooth muscle relax in uterus, GI, bronchioles; urine retention (B2 detrusor, Alpha 2 internal urethral sphincter)–on alpha 2: vasoconstriction–on alpha 1: pupil dilation

Question 5

imaging of adrenal and normal size

Answer 5

—ab US–CT–MRI1.5 cm max width

Question 6

differentials for adrenal mass/asymmetry

Answer 6

–hypertrophy of normal tissue–granuloma–cyst–hemorrhage/hematoma–inflammatory tissue–neoplasia

Question 7

T/Fadrenalectomy is the treatment of choice if an adrenal mass is functional or malignant and has not metastasized

Answer 7

TRUEguidelines that suggest malignancy:sizeinvasionadditional masses ID’d

Question 8

diagnosis of a functional adrenal tumor

Answer 8

–excess cortisol, catecholamines, aldosterone, sex steroids cortisol secreting: adrenal (asymmetrical—carcinoma vs adenoma) or pituitary dependent (symmetrical; majority 85%) –> Low dose dexamethasone suppressioncatecholamine secreting: Pheochromocytoma (asymmetrical similar to cortisol secreting tumors or carcinomas)

Question 9

results of a low dose dexamethasone suppression test for distinguishing adrenal vs pituitary dependent hyperadrenocorticism

Answer 9

GOAL: to suppress at 4 and/or 8 hr to 50% of baselineadrenal dependent will not suppress BUT 40% of pituitary dependent will also not suppressif dog has non cortisol secreting adrenal mass (pheochromocytoma) AND pituitary dependent hyperadrenoscorticism—suppression is seensingle ACTH test will be low if adrenal dependent (bc negative feedback to pituitary)

Question 10

pheochromocytoma

Answer 10

chromaffin cells—excessive catecholamines from adrenal medulla (sporadic and unpredictable)metastatic, large, can be invasivesevere systemic hypertension (BP and retinal exam)normal bloodwork, normal adrenal function tests, adrenal mass on US +/- invasion with normal contralateral glandcan test urine catecholamine concentrations

Question 11

perioperative mgmt of cortisol secreting tumors

Answer 11

–treat with trilostane 3-4 weeks pre-op to control metabolic derangements prior to surgery–check BP and tx hypertension if necessary (ACE-i)–full staging to rule out mets–blood type and crossmatch; TEG (hypercoag)–imaging (US, CT, MRI) to look at invasiveness

Question 12

considerations prior to anesthesia for cortisol secreting tumors

Answer 12

–cortisol induced immunosuppression–thromboembolic dz/hypercoagulation–systemic hypertension–delayed wound healing (not proven)–development of hypoadrenocorticism post op–pancreatitis–fragile atrophic skin (cats)

Question 13

MOA trilostane

Answer 13

competitive inhibitor of 3 beta hydroxysteroid dehydrogenase which inhibits cortisol production

Question 14

2 common complications post adrenalectomy and how to prevent

Answer 14

1. pulmonary thromboembolism: pretreat with heparin (heparin in plasma transfusion during surgery and SQ heparin post op)—source of antithrombin III; ambulation2. HYPOadrenocorticism: exogenous GCC (dex, pred) and MCC (desoxycorticosterone–Percorten) supplementation, monitor electrolytes, taper usually over 3-4 months

Question 15

gold standard to diagnose pulmonary thromboembolism

Answer 15

selective pulmonary angiography(other diagnostics: A-a gradient/ABG, thoracic radiographs, D dimers)

Question 16

perioperative mgmt for suspected pheochromocytoma

Answer 16

similar to cortisol secreting tumors–CBC, Chem, UA–check BP and tx hypertension; RETINAL exam–pretreat with phenoxybenzamine (decr mortality from 48% to 13%) 2-3 weeks preoperative 0.5 mg/kg q12hr–EKG (propanolol/atenolol–B antagonist if tachycardia): alpha antagonist should be given FIRST–full staging to rule out mets–blood type and crossmatch; TEG (hypercoag)–imaging (US, CT, MRI) to look at invasiveness

Question 17

role of phenoxybenzamine for pheochromocytomas according to Herrera et al JVIM 2008

Answer 17

alpha adrenergic blocker0.5-2.5 mg/kg PO q12 hr 2-3 weeks before surgerydecr mortality 48% to 13%

Question 18

anesthetic considerations for pheochromocytoma patient

Answer 18

—ventricular arrhythmias (lidocaine, esmolol)—BP monitor for hypertension (phentolamine, nitroprusside)

Question 19

approaches to adrenal gland (4)

Answer 19

–ventral midline laparotomy +/- paracostal incision–flank approach laparotomy (uncomplicated cases)–intercostal approach laparotomy (RIGHT adrenal–may be superior to flank due to location of gland)–laparoscopic adrenalectomy (capsule disturbance in all dogs, gland removed in pieces)—risk potential seeding+/- embolectomy (rumel tourniquet placement +/- hypothermia)+/- ureteronephrectomy

Question 20

reports of caval invasion with cortisol secreting tumors vs pheochromocytomas

Answer 20

cortisol tumors: 15% (11-16%)pheochromocytomas: 40% (35-55%)more common with right sided masses

Question 21

perioperative mortality rates following adrenalectomy for treatment of malignant neoplasia

Answer 21

20-60% (adrenocortical)20-50% (pheochromocytomas)more recently, best success has been around 20% mortality (better mgmt)

Question 22

T/F adrenal tumor invasion into the vena cava is associated with increased mortality

Answer 22

FALSE contradicting evidenceMOST recent Barrera JAVMA 2013extent of invasion most important factor for mortality(risk 4x likely to die) if invasion extends cranial to hepatic hilus.vsKyles JAVMA 2003 that said invasion did not change MM rates

Question 23

3 clinical signs of ferrets with endocrine neoplasia

Answer 23

alopeciaenlarged vulvareturn to male sexual behavior in male castrated patients

Question 24

adrenal tumors in ferrets

Answer 24

common and often bilateralTx: subtotal bilateral adrenalectomy (total left, partial right)low mortalitylow need for post op GCCrecurrence 15%