HYPERKALAEMIA
HYPERPARATHYROIDISM
HYPERMETROPIA
Light rays
Light rays
Light rays
Light rays
from near
focused
from near
focused
on retina
object
behind
retina
HYPERMETROPIA
Excessive sweating may be caused by hot
weather, exercise, or anxiety. In some
cases it is due to an infection,
thyrotoxi-
cosis
,
hypoglycaemia
,
or a nervous system
disorder. Usually, the disorder has no
known cause, and begins at puberty,
disappearing by the mid-20s or early 30s.
If hyperhidrosis is persistent and can-
not be controlled by
antiperspirants
,
surgery may be considered to destroy
the nerve centres that control sweating.
hyperkalaemia
Abnormally high blood
levels of
potassium
,
often due to failure
of the kidneys to excrete it.
hyperkeratosis
Thickening of the skin's
outer layer due to an increased amount
of
keratin
.
The most common forms of
hyperkeratosis affect small, localized
areas of skin and include
corns
,
calluses
and
warts
.
A rare, inherited form affects
the whole of the soles and palms. The
term hyperkeratosis may also be used
to describe thickening of the nails.
hyperlipidaemias
Metabolic disorders
that are characterized by high levels of
lipids
in the blood. Hyperlipidaemias may
be inherited or associated with another
disorder, such as
hypothyroidism
,
diabetes
mellitus
,
kidney failure
,
or
Cushing's syn-
drome
.
They may also be a result of use
of
corticosteroid drugs
.
Hyperlipidaemias
are associated with
atherosclerosis
and
coronary artery disease
.
The signs depend on the type of hyper-
lipidaemia and may include fatty nodules
in the skin or over joints, and a white line
around the rim of the
cornea
. Diagnosis
depends on
blood tests
. Treatment aims
to reduce blood lipid levels, usually by
a low-fat diet and
lipid-lowering drugs
.
hypermetropia
Commonly known as
longsightedness, hypermetropia is an
error of
refraction
that initially causes
difficulty in seeing near objects and
then affects distance vision.
Hyper-
metropia tends to run in families.
Hypermetropia is caused by the eye
being too short from front to back,
which results in images not being clearly
focused on the
retina
. The error is pre-
sent from birth, but symptoms generally
do not appear until later life because
the focusing power of
accommodation,
which compensates for hypermetropia,
declines with age.
Glasses
or
contact lenses
with convex
lenses reinforce focusing power.
hypernephroma
A type of
kidney can-
cer
, also known as renal cell carcinoma.
hyperparathyroidism
Overproduc-
tion of parathyroid hormone by the
parathyroid glands
that raises the calci-
um level in the blood (
hypercalcaemia
)
by removing calcium from bones. This
may lead to bone disorders, such as
osteoporosis
. To try to normalize the
high calcium level, the kidneys excrete
large amounts of calcium in the urine,
which can lead to the formation of kid-
ney stones (see
calculus, urinary tract
).
Hyperparathyroidism is most often
caused by a small noncancerous tumour
of 1
or more of the parathyroid glands. It
may also occur when the glands be-
come enlarged for no known reason. It
usually develops after age 40 and is
twice as common in women as in men.
Hyperparathyroidism may cause de-
pression and abdominal pain. However,
often the only symptoms are those
caused by kidney stones. If hypercal-
caemia is severe, there may be nausea,
tiredness, excessive urination, confu-
sion, and muscle weakness.
H
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