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Functional Assessment of Urinary Neuro-biogenic Amines—A COMPREHENSIVE GUIDE 

79

dulla’s metabolism of epinephrine prior

to its release into circulation.

Effects:

Decreased

levels of metaneph-

rine may occur when epinephrine

levels decrease. Phenylethanolamine

N-methyltransferase (PNMT) deficien-

cy or 21-dehydroxylase deficiency may

decrease epinephrine and metaneph-

rine levels. Studies indicate that 21-de-

hydroxylase deficiency may decrease

plasma epinephrine and metanephrine

concentrations and urinary epinephrine

excretion by 40 to 80%. PNMT deficien-

cy may also elevate norepinephrine lev-

els. Decreased metanephrine levels may

occur if catechol-O-methyltransferase

(COMT) function is deficient or inhib-

ited in adrenal cells. COMT requires

magnesium and S-adenosyl-methionine

cofactors.

Pure autonomic failure is associated

with low levels of epinephrine and me-

tanephrine. Rare, inherited conditions

such as dopamine beta-hydroxylase

(D

H) deficiency and Menkes disease

may also decrease levels of norepineph-

rine, the precursor for epinephrine.

D

H requires a copper cofactor. There

is little literature describing the symp-

toms of pure epinephrine (and/or me-

tanephrine) deficiency, however, condi-

tions that may be associated with low

epinephrine levels include Addison’s

disease, diabetic nephropathy and auto-

nomic failure syndromes.

Excess

metanephrine may occur if

sulfotransferase (SULT) enzyme func-

tion is deficient. Metanephrines may be

elevated in anxiety disorders or bipolar

disorders. Physical conditions, including

congestive heart failure, porphyria, hy-

perthyroidism and some autoimmune

conditions. Most catecholamines are

metabolized in the cells that produce

them; metanephrine levels may ele-

vate when epinephrine levels elevate.

Studies indicate that hypertensive males

with obstructive sleep apnea have high-

er urinary metanephrine and norme-

tanephrine levels. Epinephrine and

metanephrine may elevate when cate-

cholamine-secreting tumors are present.

See Adrenal and paraganglia tumors for

more information. Excess metanephrine

symptoms (excess epinephrine symp-

toms) may include:

Symptoms of elevated epinephrine

may include:

Headaches (severe)

High blood pressure

Excess sweating (generalized)

Racing heart (tachycardia)

Anxiety or nervousness

Tremors

Epigastric pain (lower chest or

upper abdomen)

Nausea or vomiting

Weight loss

Heat intolerance

Epinephrine is usually present in the

urine in small fluctuating amounts and

may be increased during and shortly af-

ter stress exposures. Monoamine oxidase

inhibitors may elevate epinephrine and

metanephrine levels.