What are the triggers for the secretion of catecholamines in pheochromocytoma?
Unlike the healthy adrenal medulla, pheochromocytomas are not innervated, and catecholamine release is not precipitated by neural stimulation. The trigger for catecholamine release is unclear, but multiple mechanisms have been postulated, including direct pressure, medications, and changes in tumor blood flow.
How is pheochromocytoma different from paraganglioma?
General Information About Pheochromocytoma and Paraganglioma
- Pheochromocytoma and paraganglioma are rare tumors that come from the same type of tissue.
- Pheochromocytoma is a rare tumor that forms in the adrenal medulla (the center of the adrenal gland).
- Paragangliomas form outside the adrenal gland.
Is Metyrosine still used?
This medication is used to treat high blood pressure in people with a certain adrenal gland tumor (pheochromocytoma). Metyrosine is used to prevent high blood pressure before and immediately after surgery to remove the tumor. It is also used long-term in people who cannot have the surgery.
How does pheochromocytoma cause high blood pressure?
Pheochromocytomas produce high levels of chemicals called catecholamines, which are strong hormones associated with stress, and they act on the cardiovascular system to increase heart rate, blood pressure, and blood flow.
Why is dopamine contraindicated in pheochromocytoma?
Dopamine (applies to dopamine) pheochromocytoma Major Potential Hazard, High plausibility. The use of dopamine is contraindicated in patients with pheochromocytoma. The catecholamine effects of dopamine may aggravate this condition.
What stimulates the release of catecholamines?
Splanchnic nerve stimulation is the physiological stimulus for catecholamine secretion. Stimulation of the splanchnic nerves results in the release of ACh from nerve endings in the adrenal medulla.
What are the Vasoconstrictors under catecholamines?
Epinephrine and norepinephrine are frequently used as vasopressor agents to treat acute hypotensive states, as well as in treatment algorithms for cardiac arrest. Their affinity to the alpha-1 receptor also is used to induce localized vasoconstriction to reduce bleeding during procedures such as wound closure.
What hormones are secreted by pheochromocytoma?
Key Points about Pheochromocytomas A pheochromocytoma is a tumor in the adrenal gland. It causes the gland to make too much of the hormones epinephrine and norepinephrine. This tumor usually occurs when you are in your 30s, 40s, or 50s.
What is Metyrosine used for?
Metyrosine belongs to the general class of medicines called antihypertensives. It is used to treat high blood pressure (hypertension) caused by a disease called pheochromocytoma (a noncancerous tumor of the adrenal gland).
What is the mechanism of action of guanethidine?
Guanethidine works by decreasing the heart rate and relaxing the blood vessels so that blood can flow more easily through the body, thereby reducing these risks. It is a postganglionic sympathetic nerve terminal blocker that prevents the release of norepinephrine from nerve terminals.
Why we give alpha blocker before beta blocker in pheochromocytoma?
Beta blockers are used if significant tachycardia occurs after alpha blockade. Beta blockers are not administered until adequate alpha blockade has been established, however, because unopposed alpha-adrenergic receptor stimulation can precipitate a hypertensive crisis.
Why are beta blockers contraindicated in pheochromocytoma?
Beta-blockers must never be started prior to adequate alpha-blockade, since in the absence of beta-2-mediated vasodilation, profound unopposed alpha-mediated vasoconstriction may lead to hypertensive crisis or pulmonary edema.
Do catecholamines cause vasoconstriction or vasodilation?
The catecholamines alter the blood pressure by altering the vascular resistance. Control of the vascular resistance is achieved through vasoconstriction and vasodilation.
Does pheochromocytoma increase cortisol?
Patients with pheochromocytoma had higher (P < . 05) circulating concentrations of cortisol, 11-deoxycortisol, 11-deoxycorticosterone, and corticosterone than patients with primary hypertension.
What syndromes are associated with pheochromocytoma?
Although pheochromocytoma has classically been associated with 3 syndromes—von Hippel-Lindau (VHL) syndrome, multiple endocrine neoplasia type 2 (MEN 2), and neurofibromatosis type 1 (NF1)—there are now 10 genes that have been identified as sites of mutations leading to pheochromocytoma.
How is pheochromocytoma diagnosed in hypertension (high blood pressure)?
Pheochromocytoma is diagnosed by measuring elevated levels of metanephrines (catecholamine metabolites) in blood or urine. CT scanning or MRI is the preferred technique for localizing pheochromocytomas (see the image below). Surgical resection of the tumor is the treatment of choice and usually cures the hypertension (see Workup and Treatment).
What is the prognosis of pheochromocytoma?
Practice Essentials. A pheochromocytoma (see the image below) is a rare, catecholamine-secreting tumor that may precipitate life-threatening hypertension. The tumor is malignant in 10% of cases but may be cured completely by surgical removal.
What are the neurologic complications of pheochromocytoma-induced hypertensive crisis?
A pheochromocytoma-induced hypertensive crisis may precipitate hypertensive encephalopathy, which is characterized by altered mental status, focal neurologic signs and symptoms, or seizures. Other neurologic complications include stroke from cerebral infarction or an embolic event secondary to a mural thrombus from dilated cardiomyopathy.