What are the diagnostic criteria for nephrotic syndrome?
Nephrotic syndrome is a syndrome that results from severe proteinuria. Heavy glomerular
protein losses (3.5 g in an adult or .40 mg/m2/hour in a child) lead to the other three
criteria for nephrotic syndrome: hypoalbuminemia, hyperlipidemia, and usually edema.
From a practical standpoint, measuring a urine total protein/creatinine ratio is preferable
to collecting a 24-hour urine for protein. A ratio of 3.5 correlates with nephrotic-range
proteinuria.
2. What is minimal change disease (minimal change nephrotic syndrome)?
Minimal change disease (MCD) is a disorder of glomeruli that leads to heavy proteinuria.
Renal biopsy shows normal glomeruli by light microscopy but will show effacement of the
podocyte foot processes by electron microscopy. Immunofluorescent microscopy typically
is negative, although some patients may show staining for immunoglobulin M (IgM) in the
mesangial regions of the glomeruli. Technically, a patient cannot be said to have MCD with
certainty without having had a kidney biopsy. However, so many young children with
nephrotic syndrome have MCD that kidney biopsies are only performed in those children
with atypical findings or in those who are resistant to immunosuppressive therapy. Older
adolescents and adults are diagnosed with MCD after a kidney biopsy is performed.
3. How likely is MCD to be the cause of nephrotic syndrome in any individual?
MCD is the cause of nephrotic syndrome in about 90% of children younger than age 6, in
about 65% of older children, and in about 20% to 30% of adolescents. In adults only about
10% to 25% of nephrotic syndrome results from MCD, but it represents the third most
common cause of nephrotic syndrome in adults after membranous nephropathy and focal,
segmental glomerulosclerosis.
4. What causes MCD?
MCD is an immune-mediated disease, felt to be mediated by a circulating factor capable of
inducing proteinuria. Presumably the circulating factor is secreted by lymphoid cells, and it
functions as a vascular permeability factor that directly affects the function of the podocytes.
Although the majority of cases of MCD are idiopathic, MCD, particularly in adults, may be
associated with neoplastic disease such as lymphoma, toxic or allergic reactions to drugs,
certain infections, allergies, or other autoimmune disorders.
5. How common is MCD?
The prevalence of MCD in children is about 16 per 100,000 children, but it is much less
prevalent in adults.
6. What is the typical clinical presentation of MCD?
Patients with MCD typically present with mild to severe edema. Because the onset with
periorbital edema commonly follows an upper respiratory infection in young children,
nephrotic syndrome may sometimes be confused with an allergic reaction until a more
thorough evaluation is performed. I
Nephrotic syndrome is a syndrome that results from severe proteinuria. Heavy glomerular
protein losses (3.5 g in an adult or .40 mg/m2/hour in a child) lead to the other three
criteria for nephrotic syndrome: hypoalbuminemia, hyperlipidemia, and usually edema.
From a practical standpoint, measuring a urine total protein/creatinine ratio is preferable
to collecting a 24-hour urine for protein. A ratio of 3.5 correlates with nephrotic-range
proteinuria.
2. What is minimal change disease (minimal change nephrotic syndrome)?
Minimal change disease (MCD) is a disorder of glomeruli that leads to heavy proteinuria.
Renal biopsy shows normal glomeruli by light microscopy but will show effacement of the
podocyte foot processes by electron microscopy. Immunofluorescent microscopy typically
is negative, although some patients may show staining for immunoglobulin M (IgM) in the
mesangial regions of the glomeruli. Technically, a patient cannot be said to have MCD with
certainty without having had a kidney biopsy. However, so many young children with
nephrotic syndrome have MCD that kidney biopsies are only performed in those children
with atypical findings or in those who are resistant to immunosuppressive therapy. Older
adolescents and adults are diagnosed with MCD after a kidney biopsy is performed.
3. How likely is MCD to be the cause of nephrotic syndrome in any individual?
MCD is the cause of nephrotic syndrome in about 90% of children younger than age 6, in
about 65% of older children, and in about 20% to 30% of adolescents. In adults only about
10% to 25% of nephrotic syndrome results from MCD, but it represents the third most
common cause of nephrotic syndrome in adults after membranous nephropathy and focal,
segmental glomerulosclerosis.
4. What causes MCD?
MCD is an immune-mediated disease, felt to be mediated by a circulating factor capable of
inducing proteinuria. Presumably the circulating factor is secreted by lymphoid cells, and it
functions as a vascular permeability factor that directly affects the function of the podocytes.
Although the majority of cases of MCD are idiopathic, MCD, particularly in adults, may be
associated with neoplastic disease such as lymphoma, toxic or allergic reactions to drugs,
certain infections, allergies, or other autoimmune disorders.
5. How common is MCD?
The prevalence of MCD in children is about 16 per 100,000 children, but it is much less
prevalent in adults.
6. What is the typical clinical presentation of MCD?
Patients with MCD typically present with mild to severe edema. Because the onset with
periorbital edema commonly follows an upper respiratory infection in young children,
nephrotic syndrome may sometimes be confused with an allergic reaction until a more
thorough evaluation is performed. I
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