Tuesday, 24 June 2014

Pheochromocytoma

►Pheochromocytoma Key Points::
Neurofibromatosis type 1 (NF 1) was the first described pheochromocytoma-associated syndrome
►Features of Pheochromocytoma::
HTN > Headache > Perspiration > Palpitations > Anxiety > Tremors
HTN = 90% cases
Headache = 80% cases
Perspiration = 70% cases
Palpitations = 60% cases
Anxiety = 50% cases
Tremor = 40% cases
►MTC is seen in virtually all patients with MEN 2, but pheochromocytoma occurs in only about 50% of these patients. Nearly all pheochromocytomas are benign and located in the adrenals, often bilateral.
►Major metabolites in Pheochromocytoma::
Large adrenal Pheochromocytoma(>5cms):: NE > Epi
Small adrenal Pheochromocytoma(<5cms):: Epi > NE
MEN associated Pheochromocytoma:: Epi > NE (as they are usually small)
Extra-adrenal Pheochromocytoma:: NE > Epi
Overall its Nor-epinephrine
►Biochemical Diagnosis of Pheochromocytoma
Most specific :: Urinary dopamine, Plasma free normetanephrine+ Clonidine suppression test(100%) > Urinary total-metanephrine/Epinephrine/NE(99.6%) > Urinary total metanephrines and catecholamines(99%)
Most Sensitive: Plasma free metanephrine
►Imaging IOC: Adrenal/ extraadrenal- MRI ,
Extraabdominal-MIBG ,
Most accurate-DOPA - PET
But regarding extrabdominal cases when we have to rely on radionuclide scans,,, DOPA PET is IOC... It has never been in the options YET, hence MIBG is what we remember.
►Complete tumor removal is the ultimate therapeutic goal. Preoperative patient preparation is essential for safe surgery. -Adrenergic blockers (phenoxybenzamine) should be initiated at relatively low doses (e.g., 5–10 mg orally three times per day) and increased as tolerated every few days.
►Because phenoxybenzamine has a longer duration of action than phentolamine, most clinicians consider phenoxybenzamine the drug of choice for the medical management of patients with pheochromocytoma until surgery is performed

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