is characterized by reduced sweating
and is accompanied by dry, wrinkled
skin, sparse hair, small, brittle nails,
and conical teeth. Other causes of
A deficiency of
in the blood. Hypokalaemia is usually
caused by excess fluid loss due, for
example, to severe diarrhoea, but which
may be the result of treatment with
A mild degree of
. A deficiency of this
hormone results in low levels of
in the blood (
The most common cause of hypopara-
thyroidism is damage to the parathyroid
glands during surgery. Occasionally, the
parathyroid glands are absent from
birth, or they may cease to function for
no apparent reason.
A low blood calcium level may cause
those of an epileptic attack may occur.
The condition is diagnosed by
To relieve an attack of tetany, cal-
cium may be injected slowly into a vein.
To maintain the blood calcium at a nor-
mal level, a lifelong course of calcium
tablets is necessary.
The surgical removal
or destruction (by means of a radioac-
tive implant) of the
may be performed to remove
or to treat some cancers of the
growth of which is stimulated by hor-
mones secreted by the pituitary gland.
Underactivity of the
, resulting in inadequate
or more pituitary
. The effects depend on which
hormones are affected. Possible causes
, an abnormality
, or injury to
the pituitary gland. Hypopituitarism may
also follow surgery or
the pituitary gland. Treatment involves
replacing the deficient hormones.
The failure of an organ or a
body tissue to develop fully and to reach
its normal adult size.
A defect in tooth
also be caused by vitamin deficiency,
injury, or infection of a primary tooth
that interferes with enamel maturation.
hypoplastic left-heart syndrome
very serious form of congenital heart
heart disease, congenital
The baby is born with a poorly formed
often associated with
other heart defects. The
formed and blood can reach it only via a
duct (the ductus arteriosus) that links
the aorta to the pulmonary artery.
At birth, the baby may seem healthy.
However, within a day or 2 the ductus
arteriosus naturally closes off and the
breathless. In most cases, hypoplastic
left-heart syndrome cannot be treated
surgically, and most affected babies die
within a week. A few infants have been
treated with heart transplants.
A preventive treat-
to specific substances,
such as grass pollens and insect venom.
Hyposensitization involves giving grad-
ually increasing doses of the allergen so
sensitive to that substance. The treat-
ment, which may need to be repeated
annually for a few years, carries the risk
defect of the
, in which the opening of the
is on the underside of the
shaft. In some cases, the penis curves
downwards, a condition that is known
. Hypospadias can usu-
ally be corrected by surgery.
The medical term for low
. In its most common form,
known as postural hypotension, symp-
toms occur after abruptly standing or
sitting up. Normally, blood pressure in-
creases slightly with changes in posture;
in people with postural hypotension, this
normal increase fails to occur. Postural
hypotension may be a side effect of
It may also occur in people with
. Acute hypotension is
a feature of
, and may be caused
by serious injury or a disease such as