Glycerol is used in moisturizing creams.
It is also used in eardrops to soften ear-
wax and in cough remedies to help
soothe a dry, irritating cough.
glyceryl trinitrateA vasodilator drug
used to treat and prevent symptoms of
angina pectoris.High doses may cause a
headache, flushing, and dizziness.
glycogenThe main form of carbohydrate
stored in the body, found mainly in the
liver and in muscles. When there is too
much glucose in the blood, the excess
is converted to glycogen by the action
of insulin and corticosteroid hormones.
When the blood glucose level is low, gly-
cogen is converted back to glucose (a
process regulated by adrenaline and gluc-
agon) and released into the bloodstream.
glycosuriaThe presence of glucosein
the urine. Glycosuria results from failure
of the kidneysto reabsorb glucose back
into the bloodstream after the blood
has been filtered. This may be due to
hyperglycaemia, as in diabetes mellitus,
or may occur if the kidney tubules have
been damaged. However, glycosuria is
usually only significant if accompanied
by a high blood glucose level. Glyco-
suria often occurs during pregnancy
when the blood glucose level is normal.
Glycosuriais diagnosed by urinalysis.
Treatment depends on the cause.
glycosylated haemoglobinA form of
haemoglobinthat is bound to the sugar
glucose. In most people, 3–8 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 indi-
cate blood glucose levels over the
preceding 3 months.
goitreEnlargement of the thyroid gland,
visible as a swelling on the neck. The
thyroid gland may enlarge (without any
disturbance of its function) at puberty,
during pregnancy, or as a result of tak-
ing oral contraceptives. In many parts of
the world the main cause of a goitre is
lack of iodinein the diet. A condition
called toxic goitre develops in Graves’
diseaseand in other forms of hyperthy-
roidismthat lead to thyrotoxicosis. A
goitre is also a feature of different types
of thyroiditis. Other causes include a
tumour or nodule in the gland and, in
rare cases, thyroid cancer.
A goitre can range in size from a barely
noticeable lump to a large swelling, de-
pending on the cause. Large swellings
may press on the oesophagusor trachea,
making swallowing or breathing difficult.A goitre not caused by disease may
eventually disappear. Goitre due to iodine
deficiency can be treated by dietary mea-
sures. When a goitre is the result of
disease, treatment is for the underlying
disorder. Large goitres can be treated
surgically (see thyroidectomy).
goldAn antirheumatic drugused to treat
severe rheumatoid arthritisand, occasion-
ally, arthritis arising as a complication
of psoriasis. It is given either as regular
injections or orally (see auranofin). A
common adverse effect is dermatitis.
Gold may damage the kidneys, liver,
and bone marrow and may cause loss of
appetite, nausea, and diarrhoea.
golfer’s elbowA painful condition caused
by inflammation of the epicondyle(bony
prominence) on the inner elbow, at the
site of attachment of some forearm mus-
cles. Golfer’s elbow is caused by overuse
of these muscles, which bend the wrist
and fingers. Activities such as using a
screwdriver or playing golf with a faulty
grip can cause the condition. Treatment
consists of resting the elbow, applying
ice-packs, and taking analgesic drugsto
relieve pain. If the pain is severe or per-
sistent, injection of a corticosteroid drug
into the area may help.GLYCERYL TRINITRATE GOLFER’S ELBOW
G
GOITRESwelling due to enlarged
thyroid gland (goitre)