normal pull of gravity causes blood to temporarily
pool in the large veins of the legs. Any lapse
between the change of position and the signals
that activate the body’s blood pressure regulation
mechanisms, results in an inadequate blood sup-
ply to the brain that causes loss of consciousness.
Syncope following meals, called postprandial syn-
cope, also is common, as the body draws an
increased blood volume to the gastrointestinal
tract to support the functions of digestion. The
diagnostic path typically includes review of med-
ications the person is taking as well as blood tests
to measure levels of the adrenal hormones, blood
electrolytes, and blood composition. Treatment
depends on the underlying cause. When the cause
is medication, changing the DOSEor switching to a
different medication often remedies the hypoten-
sion. Neurologic and endocrine causes may
require more extensive diagnostic evaluation and
comprehensive treatment approaches.
See also ADRENAL INSUFFICIENCY; AUTOIMMUNE DIS-
ORDERS; HORMONE; PHEOCHROMOCYTOMA.68 The Cardiovascular System