120. Adrenal Glands Flashcards
general indications to perform adrenalectomy
—characteristics of malignancy—functional tumors
adrenal gland vasculature
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)
architecture and functional zones of adrenal gland
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)
actions of epinephrine and norepinephrine release
—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
imaging of adrenal and normal size
—ab US–CT–MRI1.5 cm max width
differentials for adrenal mass/asymmetry
–hypertrophy of normal tissue–granuloma–cyst–hemorrhage/hematoma–inflammatory tissue–neoplasia
T/Fadrenalectomy is the treatment of choice if an adrenal mass is functional or malignant and has not metastasized
TRUEguidelines that suggest malignancy:sizeinvasionadditional masses ID’d
diagnosis of a functional adrenal tumor
–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)
results of a low dose dexamethasone suppression test for distinguishing adrenal vs pituitary dependent hyperadrenocorticism
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)
pheochromocytoma
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
perioperative mgmt of cortisol secreting tumors
–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
considerations prior to anesthesia for cortisol secreting tumors
–cortisol induced immunosuppression–thromboembolic dz/hypercoagulation–systemic hypertension–delayed wound healing (not proven)–development of hypoadrenocorticism post op–pancreatitis–fragile atrophic skin (cats)
MOA trilostane
competitive inhibitor of 3 beta hydroxysteroid dehydrogenase which inhibits cortisol production
2 common complications post adrenalectomy and how to prevent
- 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
gold standard to diagnose pulmonary thromboembolism
selective pulmonary angiography(other diagnostics: A-a gradient/ABG, thoracic radiographs, D dimers)
perioperative mgmt for suspected pheochromocytoma
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
role of phenoxybenzamine for pheochromocytomas according to Herrera et al JVIM 2008
alpha adrenergic blocker0.5-2.5 mg/kg PO q12 hr 2-3 weeks before surgerydecr mortality 48% to 13%
anesthetic considerations for pheochromocytoma patient
—ventricular arrhythmias (lidocaine, esmolol)—BP monitor for hypertension (phentolamine, nitroprusside)
approaches to adrenal gland (4)
–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
reports of caval invasion with cortisol secreting tumors vs pheochromocytomas
cortisol tumors: 15% (11-16%)pheochromocytomas: 40% (35-55%)more common with right sided masses
perioperative mortality rates following adrenalectomy for treatment of malignant neoplasia
20-60% (adrenocortical)20-50% (pheochromocytomas)more recently, best success has been around 20% mortality (better mgmt)
T/F adrenal tumor invasion into the vena cava is associated with increased mortality
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
3 clinical signs of ferrets with endocrine neoplasia
alopeciaenlarged vulvareturn to male sexual behavior in male castrated patients
adrenal tumors in ferrets
common and often bilateralTx: subtotal bilateral adrenalectomy (total left, partial right)low mortalitylow need for post op GCCrecurrence 15%
