Childhood Nephrotic Syndrome
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Childhood nephrotic syndrome can occur
at any age but is most common between
the ages of 1? and 5 years. It seems to
affect boys more often than girls.
A
child with the nephrotic syndrome has
these signs:
-
high levels of protein in the urine
-
low levels of protein in the blood
-
swelling resulting from buildup of salt and water
The nephrotic syndrome is not itself a
disease. But it can be the first sign of
a disease that damages the kidney's tiny
blood-filtering units, called glomeruli,
where urine is made.
The kidneys are two bean-shaped organs
found in the lower back. They are about
the size of a fist. They clean the blood
by filtering out excess water and salt
and waste products from food. Healthy
kidneys keep protein in the blood, which
helps the blood soak up water from
tissues. But kidneys with damaged
filters may let protein leak into the
urine. As a result, not enough protein
is left in the blood to soak up the
water. The water then moves from the
blood into body tissues and causes
swelling. You may see swelling around
your child's eyes, belly, and legs. Your
child may urinate less often than usual
and may gain weight from the excess
water.
To
diagnose childhood nephrotic syndrome,
the doctor may ask for a urine sample to
check for protein. The doctor will dip a
strip of chemically treated paper into
the urine sample. Too much protein in
the urine will make the paper change
color. Or the doctor may ask for a
24-hour collection of urine for a more
precise measurement of the protein and
other substances in the urine.
The doctor may take a blood sample to
see how well the kidneys are removing
wastes. Healthy kidneys remove
creatinine and urea nitrogen from the
blood. If the blood contains high levels
of these waste products, some kidney
damage may have already occurred. But
most children with the nephrotic
syndrome do not have permanent kidney
damage.
In
some cases, the doctor may want to
examine a small piece of the child's
kidney under a microscope to see if
something specific is causing the
syndrome. The procedure of collecting a
small tissue sample from the kidney is
called a
biopsy,
and it is usually performed with a long
needle passed through the skin. The
child will be awake during the procedure
and receive calming drugs and a local
painkiller at the site of the needle
entry. A patient who is prone to
bleeding problems may require open
surgery for the biopsy. General
anesthesia will be used if surgery is
required. For any biopsy procedure, the
child will stay overnight in the
hospital to rest and allow the health
care team to address quickly any
problems that might occur.
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A strip
of chemically treated paper
will change color when
dipped in urine with too
much protein. |
Minimal Change
Disease
The most common form of the nephrotic
syndrome in children is called
minimal change disease.
Doctors do not know what causes it. The
condition is called minimal change
disease because children with this form
of the nephrotic syndrome have normal or
nearly normal biopsies. If your child is
diagnosed with minimal change disease,
the doctor will probably prescribe
prednisone, which belongs to a class of
drugs called corticosteroids. Prednisone
stops the movement of protein from the
blood into the urine, but it does have
side effects that the doctor will
explain. Following the doctor's
directions exactly is essential to
protect your child's health. The doctor
may also prescribe another type of drug
called a diuretic, which reduces the
swelling by helping the child urinate.
When protein is no longer present in the
urine, the doctor will begin to reduce
the dosage of prednisone. This process
takes several weeks. Some children never
get sick again, but most do develop
swelling and protein in the urine again,
usually following a viral illness.
However, as long as the child continues
to respond to prednisone and the urine
becomes protein free, he or she has an
excellent long-term outlook without
kidney damage.
Children who relapse frequently, or who
seem to be dependent on prednisone or
have side effects from it, may be given
a second type of drug called a cytotoxic
agent. The agents most frequently used
are cyclophosphamide and chlorambucil.
After reducing protein in the urine with
prednisone, the doctor may prescribe the
cytotoxic agent for a while. Treatment
with cyclophosphamide and chlorambucil
usually lasts for 8 to 12 weeks.
Alternatively, cyclosporine, a drug also
used in transplant patients, may be
given. Treatment with cyclosporine
frequently continues over an extended
period.
In
recent years, doctors have explored the
use of mycophenolate mofetil (MMF)
instead of cytotoxic agents for children
who relapse frequently. MMF is an
immunosuppressant used to treat
autoimmune diseases and to keep the body
from rejecting a transplanted organ. MMF
has not been tested for treating
nephrotic syndrome in large clinical
trials, but doctors report promising
results with small numbers of patients.
MMF has milder side effects than
cytotoxic agents, but taking
immunosuppressants can raise the risk of
infection and other diseases. The good
news is that most children "outgrow"
nephrotic syndrome by their late teens
with no permanent damage to their
kidneys.
Other Conditions
That Involve the Childhood Nephrotic
Syndrome
In
about 20 percent of children with the
nephrotic syndrome, the kidney biopsy
reveals scarring or deposits in the
glomeruli. The two most common diseases
that damage these tiny filtering units
are focal segmental glomerulosclerosis
(FSGS) and membranoproliferative
glomerulonephritis (MPGN).
Since prednisone is less effective in
treating these diseases than it is in
treating minimal change disease, the
doctor may use additional therapies,
including cytotoxic agents. Recent
experience with a class of drugs called
ACE inhibitors, a type of blood pressure
drug, indicates that these drugs can
help to prevent protein from leaking
into the urine and keep the kidneys from
being damaged in children with the
nephrotic syndrome.
Very rarely, a child may be born with
congenital nephropathy, a condition that
causes the nephrotic syndrome. The most
common form of this condition is
congenital nephropathy of the Finnish
type (CNF), inherited as an autosomal
recessive trait. Another condition that
causes nephrotic syndrome in the first
months of life is diffuse mesangial
sclerosis (DMS). The pattern of
inheritance for DMS is not as clearly
understood as the pattern for CNF,
although the condition does appear to be
genetic.
Since medicines have little effect on
congenital nephropathy, transplantation
is usually required by the second or
third year of life, when the child has
grown sufficiently to receive a kidney.
To keep the child healthy, the doctor
may recommend infusions of the protein
albumin to make up for the protein lost
in urine and prescribe a diuretic to
help the child eliminate the extra fluid
that causes swelling. The child's immune
system may be weakened, so antibiotics
should be given at the first sign of
infection.
Congenital nephropathy can disturb
thyroid activity, so the child may need
a substitute hormone, thyroxine, to
promote growth and help bones mature. A
blood thinner like warfarin may be
necessary to keep the child's blood from
clotting.
A
child with congenital nephropathy may
need tube feedings to ensure proper
nutrition. In some cases, the diseased
kidney may need to be removed to
eliminate proteinuria. Dialysis will
then be required to replace kidney
function until the child's body is big
enough to receive a transplanted kidney.
Peritoneal dialysis is preferable to
hemodialysis for young children.
In
peritoneal dialysis, a catheter is
surgically placed in the child's abdomen
and then used to introduce a solution
into the abdominal cavity (the
peritoneum). The solution draws wastes
and extra fluid from the child's blood
stream. After a few hours, the solution
is drained and replaced with a fresh
supply. The drained solution carries the
waste and extra fluid out of the child's
body.
