drugs used in treatment, and others may
have to be used and treatment carried
out for a longer period. If the full course
of drugs is taken, most patients recover.
TB can be prevented by BCG vaccina-
tion, which is offered routinely at birth
or age 10–14. Any contacts of an infected
person are traced and examined, and, if
infected, are treated early to reduce the
risk of the infection spreading.
tuberosityA prominent area on a bone
to which tendonsare attached.
tuberous sclerosisAn inherited disor-
der that affects the skin and nervous
system. An acne-like condition of the
face, epilepsy, and learning difficulties
often occur. Noncancerous tumours of
the brain, kidney, retina, and heart may
also develop. There is no cure, and
treatment aims only to relieve symp-
toms. In serious cases, death occurs
before the age of 30. Genetic counselling
is recommended for affected families.
tuboplastySurgery in which a damaged
fallopian tube is repaired to treat infertility.
It may be performed by microsurgery.
tularaemiaA bacterial infection of wild
animals that is sometimes transmitted
to humans. Tularaemia does not occur
in the UK but is seen in North America.
It may result from contact with an
infected animal or carcass, or a tick, flea,
fly, or louse bite. A diagnosis is made by
blood tests. Treatment is with antibiotic
drugs. Tularaemia is fatal in 5 per cent
of untreated cases.
tumbu fly bitesA cause of myiasis.
tumourA term that describes any swel-
ling but which is generally used to refer
to an abnormal mass of tissue that forms
when cells in a specific area reproduce at
an increased rate. Tumours can be can-
cerousor noncancerous.
tumour-specific antigenA substance
secreted by a specific type of tumour
that can be detected in the blood and
may be used to help monitor a patient’s
response to therapy. Alpha-fetoprotein is
an example of a tumour-specific antigen.
tuning fork testsHearing testscarried
out to diagnose conductive deafness. In
the Weber test, a vibrating tuning fork is
held against the forehead. If there is
conductive hearing loss, the sound
seems louder in the affected ear. In theRinne test, a vibrating tuning fork is
held first near the ear, and then against
the bone behind it. If it sounds louder
when held against the bone, there is
conductive hearing loss.
tunnel visionLoss of the peripheral
visual field to the extent that only
objects straight ahead can be seen
clearly. Tunnel vision is most commonly
caused by chronic glaucoma. Retinitis
pigmentosais another possible cause.
Turner’s syndromeA disorder caused
by a chromosomal abnormalitythat only
affects females. The abnormality may
arise in 1 of 3 ways: affected females
may have only 1 X chromosome instead
of 2; they may have 1 normal and 1
defective X chromosome; or they may
have a mixture of cells (see mosaicism),
in which some of the cells are missing
an X chromosome, some have extra
chromosomes, and others have the
normal complement of chromosomes.
Turner’s syndrome causes short stature;
webbing of the skin of the neck; absence
or retarded development of sexualchar-
acteristics; amenorrhea, coarctation of
the aorta, and abnormalities of the eyes
and bones.
Treatment with growth hormonefrom
infancy helps girls with Turner’s syn-
drome to achieve near normal height.
Coarctation of the aorta is treated sur-
gically. Treatment with oestrogen drugs
induces menstruation, but it does not
make affected girls fertile.
TURPThe abbreviation for transurethral
resection of the prostate. TURP is a sur-
gical procedure in which the central
part of an enlarged prostate glandis
removed (see prostate, enlarged). A
viewing instrument called a resecto-
scope is passed along the urethrauntil
it reaches the prostate. A heated wire
loop, or sometimes a cutting edge, is
inserted through the resectoscope and
used to cut away excess prostate tissue.
twinsTwo offspring resulting from one
pregnancy. Monozygotic, or identical,
twins develop when a single fertilized
egg divides at an early stage of develop-
ment. Incomplete division of the egg
results in conjoined twins (see Siamese
twins). Monozygotic twins share the
same placenta. Dizygotic twins developTUBEROSITY TWINST