Pheochromocytoma and hyperthyroid Flashcards
Pheochromocytoma:
Incidence
Site
Malignancy
Rare tumor, of the adrenal medulla. In dogs, up to 50% are malignant and can show metastatic behavior.
Signs seen are d/t epi or norepi- release.
What are the primary effects of norepinephrine?
alpha-adrenergic stimulator
arteriolar and venular constriction, increase systolic and diastolic BP.
What are the primary effects of epinephrine?
both alpha and beta adrenergic actions.
Beta - arterial dilation, ^HR,, ^atrial contractility, ^cardiac automaticity and conduction velocity, bronchiolar smoother muscle dilation, increased lipolysis, and CNS stim.
S/S of pheochromocytoma
S/S are dependent upon type and frequency of catecholamine secretion.
- anxiety
- mental depression
- restlessness
- panting
- paroxysms of blanching or flushing
- tachycardia that is sometimes accompanied by VPCs
- paroxysmal weakness or collapse
- hypertension +/- retinopathy
- weight loss, anorexia.
Pheo Tx
Surgical Medical: -phenoxybenzamine alpha blockade PO -regitine (phentolamine) alpha blocker parenteral -propranolo beta blockade. Also, alpha block before you beta block.
Phenoxybenzamine
Alpha blocker.
Surgical survival in dogs that received at 1-2mg/kg per day for 2 weeks prior to surgery.
How do you diagnose pheochromocytoma?
- Hx
- PE
- Imaging: xrays may see adrenal tumor. U/S, CT.
- Blood pressure measurements.
- Elevated urinary epinephrine.
- Plasma free normetanephrine concentration to have excellent sensitivity and specificity.
- Plasma free metanephrine has moderate sensitivity and high specificity.
What structure may a pheochromocytoma invade?
posterior vena cava
Ascites often seen in these cases and needs to be differientiated from other possible causes; right sided CHF, chronic liver disease, hypoproteinemia, and other abdominal tumors.
Incidence of hyperthyroidism
Older cats
Mean age 13 y (1-22)
Only 5% are < 10yr at time of dx.
No breed or sex predilection.
Thyroid pathology
Unilateral 30%
Bilateral 70%
Adenomatous hyperplasia 98%
Adenocarcinoma 2%
What are typical s/s associated with hyperthyroidism?
wt loss, despite polyphagia v/d PU/PD restlessness, nervousness unkempt hair coat tachycardia +/- murmur palpable goiter \+/- hyperthyroidism \+/- retinal hemorrhage
What are the treatment options for hyperthyroidism?
Surgical
Radiation
Medical management
Drug used to treat hyperthyroidism
Tapezole = methimazole
Toxic effects of methimazole
anorexia vomiting lethargy facial pruritus bleeding diathesis icterus/hepatopathy hematologic effects (thrombocytopenia, eosinophilia, lymphocytosis, etc)
Surgery pre-op requirements for thyroidectomy
restore euthyroidism
assess kidney function
propranolol or atenolol to counter tachycardia
Anesthesia: avoid atropine, ace, and ketamine.
