Encyclopedia of Health and Medicine

134 The Endocrine System
health conditions that have developed as a consequence
of iron deposits, such as heart disease or
diabetes. The damage iron deposits cause is irreversible,
though once treatment begins most secondary
conditions improve.
DONATING BLOOD
Some BLOOD banks and blood collection centers
accept blood withdrawn as treatment hemochromatosis
for donation and use it to produce blood
products. As blood products are limited and
sometimes scarce, it is worthy for people who
are receiving therapeutic phlebotomy for
hemochromatosis to look for centers who will
accept their blood for such use. Otherwise the
center discards the blood.
Risk Factors and Preventive Measures
Because hemochromatosis is hereditary, the key
risk for developing it is family history. Doctors
have only recently recognized the potentially
widespread existence of hemochromatosis, however;
and many family medical histories make no
reference to the condition. People who have family
histories for early-onset liver disease, heart disease,
or diabetes should have basic blood tests for
iron levels included with their routine medical
examinations as a screening precaution. Early
diagnosis and treatment prevent most of the complications
that can develop and minimize the
severity of the condition and its affect on health.
See also BLOOD DONATION; PHENYLKETONURIA (PKU);
WILSON’S DISEASE.
hirsutism Excessive growth of body HAIR in a
male pattern, typically involving the face, chest,
back, arms, and legs. The hair follicles on these
SKIN surfaces are sensitive to TESTOSTERONE and
other ANDROGENS (“male” hormones), the hormones
that stimulate hair growth in both men
and women. Though hirsutism affects men and
women, it is especially a concern for women for
clinical as well as cosmetic reasons. Hirsutism may
result from the hair follicles being overly sensitive
to the effects of androgens (with normal levels of
androgens in the BLOOD) or an excess of androgens
in the blood circulation.
In the latter circumstance, researchers believe
the culprit is overactivity of an enzyme, 5-alpha
reductase, that converts testosterone to dihydrotestosterone,
the androgen form that stimulates
hair growth. Excessive blood levels of
testosterone may result from androgen-secreting
tumors that form in the OVARIES or the adrenal cortex
of the ADRENAL GLANDS, the two primary
sources of endogenous testosterone. Women athletes
who use ANABOLIC STEROIDS AND STEROID PRE-
CURSORS may also develop hirsutism. INSULIN
RESISTANCE and POLYCYSTIC OVARY SYNDROME (PCOS),
existing independently or as constituents of
INSULIN resistance, are strongly associated with hirsutism
in women. In some situations the endocrinologist
cannot determine a definitive cause for
hirsutism (idiopathic hirsutism).
The diagnostic path includes blood tests to measure
hormone levels, hormonal responses, and
insulin sensitivity. The precise tests depend on the
findings of preliminary tests. ULTRASOUND or MAG-
NETIC RESONANCE IMAGING (MRI) of the ovaries or
imaging procedures to visualize the adrenal glands
may identify any tumors. Treatment depends on
any identified cause and may combine HORMONE
THERAPY to suppress androgen production or binding
with cosmetic therapies to remove or minimize
excessive hair. The most commonly used hormone
therapy is the oral contraceptive (birth control pill),
which regulates the hormonal cycle of the ovaries.
The endocrinologist may prescribe other hormone
products, such as CORTICOSTEROID MEDICATIONS, to
suppress the HORMONE production of the adrenal
cortex. These methods are effective for many
though not all people who have hirsutism.
Cosmetic approaches include electrolysis or laser
therapy to permanently destroy hair follicles.
Shaving and chemical depilatories (hair removers)
are sometimes effective though require frequent
use. Hirsutism can be emotionally difficult for those
who have it, especially women, though men as well
may find the condition distressing.
See also CONTRACEPTION; GENETIC DISORDERS; POR-
PHYRIA.
hormone A chemical that travels through the
blood circulation and influences the functions of
cells within the body. The body produces dozens
of hormones of two primary chemical forms, peptides
and steroids. A hormone affects only the cells
that have receptors for it, and only when it binds