HAEMODIALYSIS
HAEMOLYTIC DISEASE
Loss of sex drive and a reduction in the
size of the testes are often the first signs.
Excess iron over a period of time causes
liver enlargement and
cirrhosis
,
and can
lead to
diabetes meUitus
,
bronzed skin
coloration, cardiac
arrhythmia
, and, even-
tually,
liver failure
and
liver cancer
.
Diagnosis is based on
blood tests
and
a
liver biopsy
. Treatment is by regular
venesection
. (See also
haemosiderosis.
)
haemodialysis
One of the 2 means of
dialysis
used to treat
kidney failure
.
haemoglobin
The oxygen-carrying pig-
ment that is present in red
blood cells
.
Haemoglobin molecules, which are pro-
duced by
bone marrow,
are made up of
4 protein chains (2 alpha- and 2 beta-
globin) and 4 haem (a red pigment that
contains iron).
HAEMOGLOBIN
Alpha-globin
chain
Beta-globin
chain
Iron
STRUCTURE OF HAEMOGLOBIN
Oxygen from the lungs enters red
blood cells in the bloodstream. The oxy-
gen then combines chemically with the
haem within the haemoglobin to form
oxyhaemoglobin, which gives blood in
the
arteries
its distinctive bright red
colour and is carried around the body.
In areas that need oxygen, the oxyhaem-
oglobin releases its oxygen and reverts
to haemoglobin, giving blood in the
veins
its distinctive darker colour.
Some defects in haemoglobin produc-
tion result from a
genetic disorder
; such
defects are subdivided into errors of
haem production, known as
porphyrias
,
and those of globin production, known
as
haemoglobinopathies
. Other defects,
such as some types of
anaemia
,
have a
nongenetic cause.
haemoglobinopathy
A term used to
describe the
genetic disorders
in which
there is a fault in the production of the
globin chains of
haemoglobin
. Examples
of haemoglobinopathies include
sickle
cell anaemia
and the
thalassaemias
.
haemoglobinuria
The presence in the
urine of
haemoglobin
. Haemoglobin is
mainly contained in red blood cells, but a
small amount is free in the blood plas-
ma. Excessive breakdown of red blood
cells, which may be due to heavy exer-
cise, cold weather, falciparum
malaria
,
or haemolytic
anaemia
, increases the
concentration of free haemoglobin in
the plasma. The excess haemoglobin is
excreted in the urine.
haemolysis
The destruction of red
blood
cells
.
Haemolysis is the normal process
by which
old red blood cells
are
destroyed, mainly in the
spleen
.
Biliru-
bin
, a waste product of haemolysis, is
excreted into the
bile
by the liver.
Abnormal haemolysis, in which red
blood cells are destroyed prematurely,
may cause anaemia and jaundice (see
anaemia, haemolytic
).
haemolytic anaemia
See
anaemia, hae-
molytic
.
haemolytic disease of the newborn
Excessive
haemolysis
(destruction of
red blood cells) in the fetus and new-
born by
antibodies
produced by the
mother. Haemolytic disease of the new-
born is most often caused by
Rhesus
incompatibility
. This occurs when a moth-
er with Rh-negative type blood, who has
previously been exposed to Rh-positive
blood through birth, miscarriage, abor-
tion, or amniocentesis, is pregnant with
a baby that has Rh-positive blood.
Haemolytic disease has become un-
common since the introduction of routine
preventative treatment for Rh-negative
women during pregnancy (see
anti-D
(Rh
0
immunoglobulin)
.
In mild cases of haemolytic disease,
the newborn baby becomes slightly jaun-
diced during the first 24 hours of life
(due to excess bilirubin in the blood)
and slightly anaemic. In more severe
cases, the level of
bilirubin
in the blood
H
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