GLYCOSURIA
G
TYPES AND CAUSES
There are several types of GSD. One is
glycogen storage disease type I. This
condition is caused by a defect in glu-
cose-
6
-phosphatase,
an
enzyme
that
aids
gluconeogenesis
in the liver. The
majority of GSDs have an autosomal
recessive
pattern
of inheritance: they
occur when a child inherits the affected
gene
from parents who are carriers.
SYMPTOMS AND SIGNS
These features vary according to the
particular type of GSD. Symptoms and
signs may include failure to grow nor-
mally during childhood; muscle cramps
and wasting; an enlarged liver; and low
blood glucose levels.
DIAGNOSIS, TREATMENT, AND OUTLOOK
Diagnosis may involve biochemical tests
(see
biochemistry
)
on tissue samples from
a muscle or a liver
biopsy
.
Some types of GSD can be controlled
by management of symptoms, includ-
ing by diet control. In certain cases a
liver transplant
is an option, but in other
cases no treatment is possible and death
occurs in the first few years of life.
glycosuria
The presence of
glucose
in the urine.
Glycosuria results from failure of the
kidneys
to reabsorb glucose back into
the bloodstream after the blood has
been filtered to remove waste products.
Failure to reabsorb sufficient glucose
may be due to
hyperglycaemia
(an ab-
normally high blood glucose level), as
in
diabetes mellitus
.
It may also occur if
the kidney tubules have been damaged
(for example, through drug poisoning)
and thus cannot reabsorb even normal
amounts. In addition, glycosuria may
occur during pregnancy, but is usually
not serious provided that the blood glu-
cose level is normal and there are no
other symptoms.
Glycosuria is diagnosed by testing the
urine
(see
urinalysis
) .
The
treatment
depends on the cause.
glycosylated haemoglobin
A form of
haemoglobin
that is bound to
the
sugar
glucose.
In
most
people,
between three and eight per cent of
haemoglobin is glycosylated. In people
with
diabetes mellitus
,
the level of glyco-
sylated haemoglobin may be raised if
treatment has not kept the blood glu-
cose level within the normal range.
Glycosylated haemoglobin levels in -
dicate blood glucose levels over the
preceding three months.
GM foods
See
genetically modified foods.
gnathic
Pertaining to the
jaw
,
as in gnathitis
(inflammation of the jaw).
goitre
Enlargement of the
thyroid gland
,
visible
as a swelling at the base of the neck.
CAUSES
The thyroid gland may enlarge (with-
out any disturbance of its function) at
puberty
,
during pregnancy, or in women
taking
oral contraceptives
.
In many parts
of the world the main cause of a goitre
is a dietary deficiency of
iodine
,
an ele-
ment that the thyroid needs in order to
produce thyroid hormone. This form of
the condition is called
endemic goitre
.
A condition called toxic goitre devel-
ops as a result of
thyrotoxicosis
in
Graves’
disease
and in certain other forms of
hyperthyroidism
(overactivity of the thy-
roid gland). A goitre is also a feature of
different types of
thyroiditis
(inflamma-
tion of the thyroid gland), including
Hashimoto’s thyroiditis
and
De Quervain’s
thyroiditis
.
Other causes include a tumour
or nodule in the gland and, in rare
cases,
thyroid cancer
.
There are also various types of fam-
ilial goitre. This kind of goitre is caused
by an inherited thyroid disorder; it
appears during childhood and is often
associated with signs of
hypothyroidism
,
such as learning difficulties.
SYMPTOMS
A goitre can range in size from a barely
noticeable lump to a large swelling, de-
pending on the cause. Large goitres may
press on the
oesophagus
or the
trachea
and
therefore
make
swallowing
or
breathing difficult.
Appearance of goitre
The thyroid gland can become enlarged for a
variety of reasons, including dietary deficiency of
iodine, inflammation, or an autoimmune disorder
affecting the gland.
DIAGNOSIS AND TREATMENT
Diagnosis may involve various
thyroid-
function tests
,
including blood tests and
radionuclide scanning
,
to determine the
activity of the thyroid gland.
A goitre that is not due to disease
may eventually disappear of its own
accord. Goitre due to iodine deficiency
can be treated by iodine-rich foods.
When a goitre is the result of disease,
treatment is for the underlying disorder.
Large goitres can be surgically removed
(see
thyroidectomy
) .
gold
A precious metal. Certain compounds
containing gold are used to treat severe
rheumatoid arthritis
and,
occasionally,
arthritis arising as a complication of
psoriasis
(see
disease-modifying antirheu-
matic drugs
) .
Gold is used in a form called sodium
aurothiomalate, given as intramuscular
injections, or is taken orally (see
auran-
ofin
) .
A common adverse effect of gold
treatment is
dermatitis
(skin inflamma-
tion). Gold may result in damage to the
kidneys, liver, and bone marrow and
may also cause loss of appetite, nausea,
and diarrhoea.
Goldberg-Maxwell syndrome
A
common
form
of male
pseudo-
hermaphroditism (a biological
intersex
condition in w hich the external geni-
talia of a genetic male resemble those of
a
female). Affected
individuals
have
testes but have a small penis and a
divided scrotum that resembles labia.
(See also
sex determination
. )
Goldenhar’s syndrome
A
rare,
congenital
type
of
dysplasia
(growth abnormality)
in w hich
the
head and face fail to develop normally
before birth. Common features include
missing or abnormally developed ears
and malformations of the jaw, mouth,
palate, eyes, and vertebrae.
golfer’s elbow
A condition caused by overuse of the
forearm muscles that bend the wrist
and fingers, usually due to activities
such as using a screwdriver or playing
golf with a faulty grip. The injury leads
to inflammation of the
epicondyle
(bony
prominence) on the inner part of the
elbow
,
where the affected muscles are
attached. Symptoms include pain and
tenderness of the elbow and sometimes
also the forearm.
346
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