Which of the following results is indicative of pheochromocytoma during clonidine suppression test?
Baseline plasma norepinephrine (NE) and epinephrine (E) levels over 2000 pg/ml or failure to suppress to less than 500 pg/ml after oral clonidine have been considered diagnostic of the presence of a pheochromocytoma.
Is clonidine used for pheochromocytoma?
In those patients with a plasma norepinephrine of less than 2000 pg/mL, the clonidine suppression test is 92% accurate in diagnosing pheochromocytoma when the normal response to clonidine is defined as total plasma catecholamines of less than 500 pg/mL.
How is a clonidine suppression test performed?
A venous cannula inserted. After 30 minutes (to allow patient to settle after venepuncture) a baseline specimen for plasma catecholamines is collected. The patient is given 300 µg clonidine hydrochloride orally. Blood for catecholamines is collected at 180 minutes.
What test is confirmatory of pheochromocytoma?
The most commonly ordered blood test for pheochromocytoma is the plasma free metanephrine test. Though more convenient to obtain than a 24-hour urine collection, plasma free metanephrine testing is plagued by frequent false positive results.
How is pheochromocytoma diagnosed?
A pheochromocytoma is a catecholamine-secreting tumor of chromaffin cells typically located in the adrenals. It causes persistent or paroxysmal hypertension. Diagnosis is by measuring catecholamine products in blood or urine. Imaging tests, especially CT or MRI, help localize tumors.
What is the mechanism of action of clonidine?
Mechanism of Action Clonidine stimulates alpha-adrenoceptors in the brain stem. This action results in reduced sympathetic outflow from the central nervous system and decreases in peripheral resistance, renal vascular resistance, heart rate, and blood pressure.
What category is clonidine?
Clonidine is in a class of medications called centrally acting alpha-agonist hypotensive agents. Clonidine treats high blood pressure by decreasing your heart rate and relaxing the blood vessels so that blood can flow more easily through the body.
What is the purpose of dexamethasone suppression test?
Test Overview The overnight dexamethasone suppression test checks to see how taking a steroid medicine called dexamethasone changes the levels of the hormone cortisol in the blood. This test checks for a condition in which large amounts of cortisol are produced by the adrenal glands (Cushing’s syndrome).
What do you do if you have a false positive drug test?
Urine drug screens are the most common test, although other body fluids may be analyzed as well. Many commonly used substances can trigger a false-positive test result. If you’re certain that the result is false, immediately take action and dispute false-positive results.
What labs are abnormal with pheochromocytoma?
Conclusions: The tests of choice to establish the diagnosis of pheochromocytoma are urinary normetanephrine and platelet norepinephrine. A combination of 131I-MIBG scintigraphy and diagnostic tests in urine, blood, or platelets does further improve the sensitivity.
Which drug is useful in the treatment of pheochromocytoma?
Noncardioselective beta blockers, such as propranolol (Inderal) or nadolol (Corgard), are the usual choice; however, cardioselective agents, such as atenolol (Tenormin) and metoprolol (Lopressor), also may be used.
What can mimic a pheochromocytoma?
Thyrotoxicosis, hypoglycemia, anxiety or panic attacks, hyperthyroidism, adrenal medullary hyperplasia, familial dysautonomia, and intracranial lesions may also have similar symptoms. Various tumors including neuroblastomas, ganglioneuroblastomas and ganglioneuromas may mimic pheochromocytomas/paragangliomas.