Nephritic Syndrome

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Nephritic SyndromeDr. Muhamed Al Rohani, MD


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Nephrotic Syndrome Proteinuria (>3.0 g/day)

Hypoalbuminemia (


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Humoral Antibody-Mediated InjuryThe major mechanisms of antibody deposition within the glomerulus are:

1. Immune complexes of circulating antibodies with extrinsic antigens that have beentrapped, or planted, within the glomerulus, as occurs in postinfectious

glomerulonephritis;

2. Reactivity of circulating autoantibodies with intrinsic autoantigens that are

components of normal glomerular parenchyma, as occurs in anti-GBM disease

(Goodpastures syndrome)

3. Intraglomerular trapping of immune complexes that have formed in the systemic

circulation:

1. Cryoglobulinemia-associated glomerulonephritis.

2. Circulating autoantibodies against neutrophil cytoplasmic antigens (antineutrophil

cytoplasmic antibodies, ANCA)

3. Endothelial antigens (antiendothelial cell antibodies, AECA).


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Factors affecting the pathogenesis of glomerular disease:

1. The capacity of the reticuloendothelial system to clear immune complexes

from the circulation,

2. The capacity of the glomerulus itself to remove deposited complexes. this is

thought to be a function of the glomerular mesangium.

Small complexes, formed in antigen excess, localize on the capillary basement

membrane.

Larger complexes tend to localize in the mesangium and cause much less

glomerular injury.


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Cellular Antibody-Independent Glomerular Injury

The cell-mediated injury is less well defined than antibody mediated glomerular injury.

T cells have also been implicated as independent mediators of glomerular injury and as modulators of theproduction of nephritogenic antibodies.

T cells interact, through their cell-surface T cell receptor/CD3 complex, with antigens presented in theglomerular endothelial, mesangial, and epithelial cells, a process that is facilitated by cell-cell adhesionand costimulatory molecules. activated T cells produce cytokines and other mediators which are potentstimuli for further leukocyte recruitment, cytotoxicity, and fibrogenesis.

Cell Proliferation and Accumulation of Extracellular Matrix:

Initially, this hypercellularity is due predominantly to infiltration of the glomerular tuft by leukocytes.Subsequently, resident glomerular cells proliferate in response to growth factors released into the local

inflammatory milieu. The proliferating cells are typically mesangial in mesangioproliferativeglomerulonephritis and both endothelial and mesangial cells in diffuse proliferative glomerulonephritis.

Factors affecting the pathogenesis of glomerular disease:

1. The capacity of the reticuloendothelial system to clear immune complexes from the circulation,

2. The capacity of the glomerulus itself to remove deposited complexes. this is thought to be a function ofthe glomerular mesangium.

Small complexes, formed in antigen excess, localize on the capillary basement membrane.

Larger complexes tend to localize in the mesangium and cause much less glomerular injury.


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Glomerular Diseases by Age and Presentation

Age (yr) Nephritic Syndrome Nephrotic Syndrome Mixed Nephritic and Nephrotic

Syndrome

< 15 Mild PIGN

IgA nephropathy

Thin basement membrane disease

Hereditary nephritis

Henoch-Schnlein purpuraLupus nephritis

Minimal change disease

Focal and segmental glomerulosclerosis

Lupus (membranous nephropathy)

Lupus nephritis

Membranoproliferative GN

1540 IgA nephropathy

Thin basement membrane disease

Lupus nephritis

Hereditary nephritis

Mesangial proliferative GN

RPGN

PIGN



Membranous nephropathy

Diabetic nephropathy

Preeclampsia

Late PIGN

IgA nephropathy

Membranoproliferative GN

Fibrillary and immunotactoid GN*

IgA nephropathy

> 40 IgA nephropathy

RPGN

Vasculitides

PIGN


Membranous nephropathy

Diabetic nephropathy


IgA nephropathy

Amyloidosis (primary)

Light chain deposition diseaseBenign nephrosclerosis

Late PIGN

IgA nephropathy

Fibrillary and immunotactoid GN*

*More commonly manifests as nephrotic syndrome.

PIGN = postinfectious glomerulonephritis; GN = glomerulonephritis, RPGN = rapidly progressive glomerulonephritis

Adapted from Rose BD. Pathophysiology of Renal Disease (2nd edition). New York: McGraw-Hill, 1987, p. 167.


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Alport's Syndrome:Hereditary nephritis is a genetically heterogenous disorder characterized by hematuria, impaired renal

function, sensorineural deafness, and ocular abnormalities. Cause is a gene mutation affecting type IV

collagen. Symptoms and signs are those of nephritic syndrome with sensorineural deafness and, less

commonly, those of ophthalmologic diseases. Diagnosis is by family history and urinalysis. Treatment is

that of chronic renal failure.

Immunoglobulin A Nephropathy:

IgA nephropathy is deposition of IgA immune complexes in glomeruli, manifesting as slowly

progressive hematuria, proteinuria, and, often, renal insufficiency. Diagnosis is based on

urinalysis and renal biopsy. Prognosis is generally good. Treatment options include ACE inhibitors,

corticosteroids, and -3 polyunsaturated fatty acids.

Rapidly Progressive Glomerulonephritis (RPGN)

(Crescentic Glomerulonephritis)Rapidly progressive GN causes microscopic glomerular crescent formation with progression to renal

failure within weeks to months. Diagnosis is based on history, urinalysis, serologic tests, and renal

biopsy. Treatment is with corticosteroids, with or without cyclophosphamide, and sometimes

plasmapheresis.


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Definition:

Acute Post Sterptococcal Glomerulonephritis is characterized by the sudden appearanceof hematuria, proteinuria and red blood cell casts in the urine, edema, andhypertension with or without oliguria.

History:

This illness was first recognized as a complication of the convalescence period ofscarlet fever in the 18th century. A link between hemolytic streptococci and acute

glomerulonephritis was recognized in the 20th century.

Acute Post Sterptococcal Glomerulonephritis

Causes:

Poststreptococcal glomerulonephritis follows infection with only certain strains ofstreptococci designated as nephritogenic.

The offending organisms are virtually always group A streptococci. APSGN follows pyodermatitis with streptococci M types 47, 49, 55, 2, 60, and 57 and

throat infection with streptococci M types 1, 2, 4, 3, 25, 49, and 12.


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Epidemiology:

Internationally: APSGN can occur sporadically or epidemically. Epidemic poststreptococcal glomerulonephritis occurs mainly in developing countries in areas

such as Africa, the West Indies, and the Middle East. Reasons for this changing epidemiologyrelate to the nutritional status of the community, the more liberal use of antibiotic prophylaxis,and, possibly, the change in the nephritogenic potential of streptococci. Among epidemic

infections with nephritogenic streptococci, the apparent clinical attack rate is 10-12%. Mortality/Morbidity:

Early death is extremely rare in children (


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Pathology :

Light microscopy The most striking finding is hypercellularity of the glomeruli. All glomeruli are affected

(diffuse) and usually to an approximately equal degree. The glomerular tufts are larger thannormal, and the cells are more numerous.

The cell types typically present include endothelial and mesangial cells and migrantinflammatory cells, which include polymorphonuclear leukocytes and monocytes.

Polymorphonuclear leukocytes are present in large numbers, hence the term exudativeglomerulonephritis.

The tubules are normal in the majority of cases.

The degree of interstitial involvement is variable. The interstitial areas show edema andinfiltration with polymorphonuclear leukocytes and mononuclear cells. The arteries andarterioles are normal.


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Immunofluorescence In biopsy samples taken in the first 2-3 weeks of illness, deposits of

immunoglobulin G and C3 in a diffuse granular pattern are present along the

glomerular capillary wall and mesangium. Immunoglobulin M may be present in small amounts. Significant amounts of

IgA suggest an alternative diagnosis.

3 different patterns of immunofluorescence called the garland pattern, the

starry sky pattern, and the mesangial pattern.


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Electron microscopy Many of the ultrastructural changes confirm the findings from light microscopy

evaluations.

The number of endothelial, mesangial, and infiltrating inflammatory cells isincreased.

The glomerular basement membrane is usually normal in thickness and

contour, although occasionally patchy thickening may be noted.

Presence of glomerular subepithelial electron-dense immune-type deposits. The

deposits are discrete and are commonly found on the part of the glomerularbasement membrane overlying the mesangium


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CLINICAL FINDINGS

History: A history suggestive of preceding streptococcal infection may

include a preceding infective episode such as pharyngitis, tonsillitis, orpyoderma.

Latent period: In general, the latent period is 1-2 weeks after a throat infection and 3-6 weeks

after a skin infection.

The onset of signs and symptoms at the same time as pharyngitis (also calledsynpharyngitic nephritis) is more likely to be immunoglobulin A (IgA)nephropathy rather than APSGN.

Dark urine (brown-, tea-, or cola-colored) This is often the first clinical symptom.

Dark urine is caused by hemolysis of red blood cells that have penetrated theglomerular basement membrane and have passed into the tubular system.

Nonspecific symptoms These can include general malaise, weakness, and anorexia and are present in

50% of patients.

Approximately 15% of patients complain of nausea and vomiting.


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Physical:

Acute nephritic syndrome Acute nephritic syndrome presenting as edema, hematuria, and hypertension with or without oliguria

is the most frequent presentation of APSGN.

Approximately 95% of clinical cases have at least 2 manifestations, and 40% have the full-blownacute nephritic syndrome.

Edema and Periorbital edema Edema is present in 80-90% of cases, and it is the presenting complaint in 60% of cases.

The onset of puffiness of the face or eyelids is sudden. It is usually prominent upon awakening and, ifthe patient is active, tends to subside at the end of the day.

In some cases, generalized edema and other features of circulatory congestion, such as dyspnea, maybe present.

Edema is a result of a defect in renal excretion of salt and water.

The severity of edema is often disproportionate to the degree of renal impairment.

Hypertension Hypertension occurs in 60-80% of cases and is more common among elderly individuals.

In 50% of cases, the hypertension can be severe; however, more often it is transient, withnormalization of BP upon therapy

If hypertension persists, it is more indicative of the progression to a more chronic stage.

Plasma renin activity is usually low due to fluid overload.

Left ventricular dysfunction

Oliguria and anuria This is present in 10-50% of cases, and, in 15%, urine output is less than 200 mL. Oliguria is indicative of the severe crescentic form of the disease.

It is often transient, with diuresis occurring within 1-2 weeks.

Hematuria This is present universally.

In 30% of cases, gross hematuria is present.


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Complications:

Complications in the acute phase include the following: Congestive heart failure

Azotemia

Early death secondary to congestive heart failure and azotemia

Complications in the chronic phase include the following: Nephrotic-range proteinuria

Chronic renal insufficiency and end-stage renal disease

Prognosis:

In children, the immediate prognosis is excellent.

In elderly patients who have congestive heart failure or azotemia in the early phase, earlymortality rates can be as high as 25%.

The long-term prognosis is debatable. Fewer than 1% of children have elevated serum creatinine values after 10-15 years of follow-

up.

Adults who develop massive proteinuria often have the garlandlike pattern of immunedeposits. Their prognosis is worse; approximately 25% progress to chronic renal failure.


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Lab Studies:

Evidence of preceding streptococcal infection

Antibody titers to extracellular products of streptococci are positive in more than 95% of patients with pharyngitisand 80% of patients with skin infections.

The antistreptolysin (ASO), antinicotinamide adenine dinucleotidase (anti-NAD), antihyaluronidase (AHase), and

antiDNAse B are commonly positive after pharyngitis, and antiDNAse B and AHase titers are more oftenpositive following skin infections.

ASO titers are frequently used to document streptococcal infection, but a more sensitive test is the streptozymetest, which tests antibodies to ASO, antiDNAse B, AHase, and anti-NAD.

Antizymogen titers that are 2 dilutions higher than the mean in healthy controls are reported to have a sensitivity of88% and a specificity of 85% in the diagnosis of streptococcal infection in patients with glomerulonephritis.

The antibody titers are elevated at 1 week, peak at 1 month, and fall toward preinfection levels after severalmonths.

Elevated BUN and creatinine could be elevated transient

Serologic findings Low serum complement levels universal finding in the acute phase of APSGN.

Most patients have marked depression of serum hemolytic component CH50 and serum concentrations of C3.

In some patients, the levels of C2 and C4 may also be decreased.

In most uncomplicated cases, the complement levels return to normal in 6-8 weeks.

Occasionally, low complement levels persist for 3 months.

Urinalysis

Hematuria and proteinuria are present in all cases. Urine sediment has red blood cells and casts, white blood cells, granular casts, and, rarely, white blood cell casts.

Hematuria usually resolves within 3-6 months but may persist as long as 18 months.

Approximately 5-10% of patients with APSGN have nephrotic-range proteinuria.

Proteinuria usually disappears in 6 months. A mild increase in urinary protein excretion is present in 15% at 3years and 2% at 10 years.


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Imaging Studies:

CXR and KUB are normal.

Renal ultrasound images usually reveal normal-sized kidneys bilaterally.

Atypical features in the early phase that suggest the need for renal biopsy include thefollowing:

Absence of the latent period between streptococcal infection and acute glomerulonephritis

Anuria

Rapidly deteriorating renal function

Normal serum complement levels

No rise in antistreptococcal antibodies

Extrarenal manifestations of systemic disease

No improvement or continued decrease in the glomerular filtration rate at 2 weeks

Persistence of hypertension beyond 2 weeks

Atypical features in the recovery phase that mandate a renal biopsy include thefollowing:

Failure of glomerular filtration rate to normalize by 4 weeks

Persistent hypocomplementemia beyond 6 weeks Persistent microscopic hematuria beyond 18 months

Persistent proteinuria beyond 6 months


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Management:Symptomatic therapy:

During the acute phase of the disease, restrict salt and water (Low-salt diet2g/d) Restricting physical activityis appropriate in the first few days.

Hypertension; If significant edema or hypertension develops, administer diuretics. Loop diuretics increase urinary output and consequently improve cardiovascular congestion and

hypertension.

ACEi or CCB. For malignant hypertension, intravenous nitroprusside.

Dialysis; is indicated if life-threatening hyperkalemia and clinical manifestations of uremia.

Medications Steroids, immunosuppressive agents, and plasmapheresis are not generally indicated.

A renal biopsy is indicated for patients with rapidly progressive renal failure. If the biopsy findings showevidence of crescentic glomerulonephritis with more than 30% of the glomeruli involved, a short course ofintravenous pulse steroid therapy is recommended (500 mg to 1 g/1.73 m2 of methylprednisone qd for 3-5d). However, no controlled clinical trials have evaluated such therapy.

Specific therapy for streptococcal infection is an important part of the therapeutic regimen.

Treat patients, family members, and any close personal contacts who are infected.

Throat cultures should be performed on all these individuals. Treat with oral penicillin G (250 mg qidfor 7-10 d) or with erythromycin (250 mg qid for 7-10 d) for patients allergic to penicillin.

This helps prevent nephritis in carriers and helps prevent the spread of nephritogenic strains to others.

Patients with skin infections must practice good personal hygiene. This is essential.

During epidemics, recommend that high-risk individuals, including close contacts and familymembers, receive empirical prophylactic treatment.

Surgical Care: Surgical care is not indicated.


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A 21 year-old woman presents with tea-colored urine,three weeks after being evaluated for

a sore throat. Physical examination is notable for a blood pressure of 170/100 and 3+ pitting

edema. Serum creatinine is 2.1 mg/dl. Urine dipstick demonstrates 2+ protein, large heme

and large leukocyte esterase.

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Nephritic Syndrome