A Boy with a 2-day history of malaise, fever to 102°F, nausea, and vomiting

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An 7-year-old boy is brought to the pediatrician's room with a 4-day history of malaise, fever to 102°F, nausea, and vomiting.
His mother reports that he has decreased urine output and that his urine is a dark, smoky color.
His blood pressure is slightly elevated, and there is some swelling of his hands and feet and around his eyes.
He has been in good health except for a sore throat a week or so ago.

1. What is the most likely diagnosis?
2. What mechanism is involved?
3. What is the usual clinical course?
4. Define the following terms, how do you differentiate Nephritic syndrome from Nephrotic syndrome ??
Glomerulonephritis:
Nephritic syndrome:
Nephrotic syndrome:
5. what are the main clinical presentation of various types of glomerulonephritis ?

Answer 



This 8-year-old child had a sore throat about 1 week before the acute onset of the current symptoms.
This is a very typical history of poststreptococcal GN.
There is usually a latent time from pharyngitis to the systemic and urinary symptoms as a result of the immune response time.
Antibodies are produced to the beta-hemolytic streptococci, and the antibody-antigen complexes are deposited in the glomerulus, leading to the clinical findings.
Diagnosis is made by the classic history, hematuria on urinalysis, elevation of the antistreptococcal antibody (ASO) titers, and a decline in the serum complement levels.
Nearly all children recover without complications. Adults do not have such a uniformly good prognosis and may develop rapidly progressive kidney disease.
If a renal biopsy were performed it most likely would show diffuse proliferative glomerulonephritis. The glomeruli would be swollen and packed with cells, and capillary lumens would be obliterated. There would be proliferation of endothelial and mesangial cells.
Polymorphonucleocytes (PMNs) would be present. These changes are expected to be uniformly present in all the glomeruli seen.

1. What is the most likely diagnosis?
Nephritic syndrome, most likely caused by poststreptococcal glomerulonephritis (GN).
2. What mechanism is involved?
Immunologic reaction against nephritogenic beta-hemolytic streptococci leading to immune complexes in the glomeruli.
3. What is the usual clinical course?
Excellent prognosis for recovery.
4. Define the following terms, how do you differentiate Nephritic syndrome from Nephrotic syndrome ??
Glomerulonephritis: Inflammation of the glomeruli.
Nephritic syndrome: A clinical syndrome of oliguria, hematuria, edema, and hypertension resulting from glomerulonephritis.
Nephrotic syndrome: A clinical syndrome of massive proteinuria, edema, hypoalbuminemia, and hyperlipidemia resulting from glomerulonephritis.
5. what are the main clinical presentation of various types of glomerulonephritis ?
1. Nephritic syndrome: characterized by oliguria, hematuria, edema, and hypertension
2. Nephrotic syndrome: characterized by massive proteinuria, edema, hypoalbuminemia, and hyperlipidemia
3. Acute renal failure
4. Chronic renal failure
5. Isolated proteinuria
6. Isolated hematuria
Discussion
Glomerulonephritis is a general term for a group of disorders in which there is a primarily immunologically mediated glomerular injury followed by secondary mechanisms of injury.

SELECTIVE CAUSES OF IMMUNE COMPLEX-MEDIATED GLOMERULONEPHRITIS

VirusesBacteriaEndogenous antigens Drugs
Mumps
Measles
Hepatitis B and C
Epstein-Barr virus
Human immunodeficiency virus
Lancefield group A beta-hemolytic streptococcus
"viridans" group of streptococci
Staphylococci
Parasites: Plasmodium malariae

DNA
Cryoglobulin
Malignant tumors

Penicillamine

The pathogenic mechanism of the primary immunologic injury is thought to have one of two basic forms:
1. Injury resulting from deposition of circulating soluble immune complexes. The nature of the antigen involved in the complex may be exogenous (e.g., Lancefield group A streptococcus) or endogenous (e.g., DNA is systemic lupus erythematosus)
2. Injury by antibodies reacting with antigens within the glomerulus. These antigens may be intrinsic glomerular antigens or antigens planted within the glomerulus from the circulation. Antibody directed against the alpha-3 chain of type IV collagen present in the basement membrane of the glomerulus is an example of intrinsic antigens. This antibody also reacts with alveolar basement membrane. This anti-GBM (glomerular basement membrane) antibody is the basis of Goodpasture syndrome

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Glomerulonephritis resulting from anti-glomerular basement membrane antibody.

After the initial immnulogic insult, several secondary events are triggered that result in further glomerular injury. These events include complement activation, platelet aggregation, fibrin deposition, and inflammation.
The clinical presentation of all the various types of glomerulonephritis can take one of six forms: >>See question 05
Initial urine analysis should show evidence of glomeulonephritis, including red cells and red cell casts. Renal function may be compromised.
Renal biopsy is not always performed in patients with glomerulonephrits. However, if biopsy is performed, the renal tissue is examined by the following processes:
1. Light microscopy.
2. Electron microscopy. The exact site of immune complex deposition is visualized with this method.
3. Immnuofluoresence. The type of immunologic injury is assessed by this method.
There is not a complete correlation between the histologic types of glomerulonephritis and the clinical presentation.
In proliferative glomerulonephritis, proliferation of endothelial, mesangial, or epithelial (in the Bowman capsule) cells may take place. Capillary lumina are occluded. In diffuse GN, infiltration of PMNs usually is seen. With excessive proliferation of the epithelial cells, crescents may form. This is referred to as crescentic GN; because the crescents clinically progress rapidly to acute renal fever (ARF), this form of GN also is known as rapidly progressive GN (RPGN).
Immunofluorescent (IF) testing depicts the type of immunologic injury. Most often it is immunoglobulin G (IgG) that is detected. In IgA nephropathy, there is mesangial deposition of IgA. In Goodpasture syndrome, there is linear deposition of IgG.
Electron microscopy (EM) helps locate the site of immune complex deposition. The possible sites include subepithelial, intramembranous, subendothelial, and mesangial. Most often the deposition of immune complexes is subepithelial. In membranoproliferative cases, the complexes are found in a subendothelial location. In minimal lesions and focal segmental glomerulosclerosis (FSGS), immune complexes are absent.

Acute Diffuse Glomerulonephritis
Acute diffuse glomerulonephritis occurs mostly in children and typically follows (1 to 4 weeks) a group A beta-hemolytic streptococcal infection. The serum complement is transiently low for several weeks. Histology reveals diffuse proliferative GN. A granular lumpy-bumpy pattern of IgG and C3 is seen on IF. EM has subepithelial electron deposits often described as dense humps.

Crescentic Glomerulonephritis
In crescentic glomerulonephritis, usually at least 50 percent of the glomeruli are involved. There are focal disruptions of the glomerular basement membrane with formation of crescents. A crescent is defined as at least three layers of cells between the visceral and parietal epithelium.
Crescentic GN is divided broadly into three categories: pauci-immune, immune-complex-mediated, and anti-basement membrane disease.
In the pauci-immune type, Wegener granulomatosis and polyarteritis nodosa are the principal examples. The immune-complex-mediated type can involve any GN that is due to immune complex deposition and may present as crescentic GN. Systemic lupus erythematosus (SLE) is an important cause of this group.
Anti-GBM disease (Goodpasture disease) involves anti-GBM antibodies, which also cross-react with alveolar basement membrane. Patients present with massive hemoptysis and ARF. Studies show linear deposition of IgG in the glomerular basement membrane. Patients with cresecentic GN present with acute renal failure with high morbidity and mortality.

Membranoproliferative (Measangiocapillary) Glomerulonephritis
Membranoproliferative (mesangiocapillary) glomerulonephritis (MPGN) may present with either nephritic or nephrotic syndrome and is associated with hypocomplementemia. There are three types of MPGN, types I, II, and III.
Type I is the most common type; complement is activated by the classical pathway. Type II is characterized by the presence of C3 nephritic factor (an IgG antibody), which binds to and prevents inactivation of C3 convertase and results in persistent activation of complement by the alternate pathway. Histology shows that the glomeruli are diffusely enlarged with marked intracapillary hypercellularity and lobular accentuation. The capillary walls are thickened. Immunofluoresence shows large, granular confluent glomerular capillary walls and mesangial deposits of C3 with IgG. EM shows subendothelial deposits in types I and III. In type II the deposits are intramembranous, resulting in a diffuse electron-dense glomerular basement membrane (dense deposit disease). Glomerulonephritis and low complement levels include acute diffuse GN, MPGN, lupus nephritis (any GN that is due to SLE), and cyrologlobulinemic GN.


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