in a similar way to
both arteries and veins. Possible side
effects include flushing, nausea, vomit-
ing, and dizziness.
potassium citrate A substance used to
relieve discomfort in mild
by making the urine less acid.
potassium permanganate A drug that
and is useful in the treatment of
It can occasionally cause irritation
and can stain skin and clothing.
potency The ability of a man to perform
; or the ability of a
drug to cause desired effects.
Pott's fracture A combined fracture and
dislocation of the ankle caused by exces-
sive or violent twisting. The
just above the ankle; in addition, the
breaks or the
ing in dislocation.
poultice A warm pack consisting of a
soft, moist substance (such as
spread between layers of soft fabric.
pox Any of various infectious diseases
characterized by blistery skin eruptions
Pox is some-
times used as a slang word for
effects may include dizziness, drowsi-
ness, and abdominal pain.
used to treat
hypertension, heart failure,
. Prazosin is also used to treat uri-
nary symptoms resulting from an enlarged
prostate gland (see
Side effects include dizziness and faint-
ing, nausea, headache, and dry mouth.
precancerous A term applied to any
condition in which there is a tendency for
cancer to develop. There are 3 types of
such conditions. In the 1st, there are no
tumours present but the condition car-
ries an increased risk of cancer. In the
nd, there are noncancerous tumours
that tend to become cancerous or are
associated with the development of can-
cerous tumours elsewhere. The 3rd type
comprises disorders which have irregu-
lar features from the beginning but do
not always become fully cancerous.
precocious pubertyThe development of
in girls and 9 in boys. It is uncom-
mon and may be caused by various
disorders that can result in production
at an abnormally early
age. Possible underlying causes include
or other brain abnormali-
ties; abnormality of the adrenal glands
congenital adrenal hyper-
plasia); ovarian cysts,
tumour in the testes. In some cases, no
underlying cause can be identified.
The hormones may cause a premature
growth spurt followed by early fusion of
the bones. As a result, affected children
may initially be tall but, if untreated, final
height is often greatly reduced.
The child's pattern of pubertal devel-
opment is assessed by a doctor.
are performed to measure hor-
ovaries and testes, and
the adrenal glands or brain, may also be
carried out, depending on the underly-
ing cause suspected.
Treatment is of the underlying cause,
and hormone drugs may be given to
delay puberty and increase final height.
predisposing factors Factors that lead
to increased susceptibility to a disease.
pre-eclampsia A serious condition in
develop in the last (3rd) trimester
of pregnancy. If severe, symptoms may
include headache, nausea and vomiting,
abdominal pain, and visual disturban-
ces. The condition, which is sometimes
called pre-eclamptic toxaemia or PET, is
more common in
st pregnancies and if
hypertension, or kid-
pre-eclampsia may lead to
For some cases of pre-eclampsia, treat-
ment is bed-rest and
. In late pregnancy, or if severe,
induction of labour
may be necessary.
pregnancy The period from
to birth. Pregnancy begins with the
of an ovum
(egg) and its
implantation. The egg develops into the
, which grows
to form the fetus. Most eggs implant
into the uterus. Very occasionally, an