Acute Glomerulonephritis

Hippocrates originally described the natural history of AGN, writing of back pain and hematuria followed by oliguria or anuria. Richard Bright (1789-1858) described AGN clinically in 1827, which led to the eponymic designation Bright disease. With the development of the microscope, Theodor Langhans (1839-1915) was later able to describe the pathophysiologic glomerular changes in AGN.

Glomerular lesions in AGN are the result of glomerular deposition or in situ formation of immune complexes. On gross appearance, the kidneys may be enlarged up to 50%. Histopathologic changes include swelling of the glomerular tufts and infiltration with polymorphonucleocytes (see Workup: Histologic Findings). Immunofluorescence reveals deposition of immunoglobulins and complement.

In PSGN, involvement of derivatives of streptococcal proteins has been reported. A streptococcal neuraminidase may alter host immunoglobulin G (IgG). IgG combines with host antibodies. IgG/anti-IgG immune complexes form and then collect in the glomeruli. In addition, elevations of antibody titers to other antigens, such as antistreptolysin O or antihyaluronidase, DNAase-B, and streptokinase, provide evidence of a recent streptococcal infection.

Glomerulonephritis associated with staphylococcal infection occurs in the setting of an active infection. Immunofluorescence microscopy of kidney biopsy specimens in these cases shows deposits that stain in a dominant or co-dominant fashion for IgA and the C3 component of complement.[3]  

Stamatiades et al determined that in PSGN and other type III hypersensitivity reactions, vascular endothelial cells in the kidney actively transport circulating immune complexes from the capillaries to the peritubular interstitial space, where they are detected and scavenged by resident macrophages. Uptake of these immune complexes by the resident macrophages triggers the release of pro-inflammatory cytokines, which in turn results in recruitment of monocytes and neutrophils into the kidney from the circulation.[6]

Structural and functional changes

AGN involves both structural changes and functional changes.

Structurally, cellular proliferation leads to an increase in the number of cells in the glomerular tuft because of the proliferation of endothelial, mesangial,[7] and epithelial cells. The proliferation may be endocapillary (ie, within the confines of the glomerular capillary tufts) or extracapillary (ie, in the Bowman space involving the epithelial cells). In extracapillary proliferation, proliferation of parietal epithelial cells leads to the formation of crescents, a feature characteristic of certain forms of rapidly progressive glomerulonephritis.

Leukocyte proliferation is indicated by the presence of neutrophils and monocytes within the glomerular capillary lumen and often accompanies cellular proliferation.

Glomerular basement membrane thickening appears as thickening of capillary walls on light microscopy. On electron microscopy, this may appear as the result of thickening of basement membrane proper (as occurs in diabetic nephropathy) or deposition of electron-dense material, either on the endothelial or epithelial side of the basement membrane. Electron-dense deposits can be subendothelial, subepithelial, intramembranous, or mesangial, and they correspond to an area of immune complex deposition.

Hyalinization or sclerosis indicates irreversible injury. These structural changes can be focal, diffuse or segmental, or global.

Functional changes include proteinuria, hematuria, reduction in GFR (ie, oliguria or anuria), and active urine sediment with RBCs and RBC casts. The decreased GFR and avid distal nephron salt and water retention result in expansion of intravascular volume, edema, and, frequently, systemic hypertension.

Poststreptococcal glomerulonephritis

Streptococcal M-protein was previously believed to be responsible for PSGN, but the studies on which this belief was based have been discounted. Nephritis-associated streptococcal cationic protease and its zymogen precursor (nephritis-associated plasmin receptor [NAPlr]) have been identified as a glyceraldehyde-3-phosphate dehydrogenase that functions as a plasmin(ogen) receptor.

Immunofluorescence staining of renal biopsy tissues with anti-NAPlr antibody revealed glomerular NAPlr deposition in early-phase acute PSGN, and glomerular plasmin activity was almost identical to NAPlr deposition in kidney biopsy tissues of acute PSGN patients. These data suggest that NAPlr may contribute to the pathogenesis of acute PSGN by maintaining plasmin activity.[8]  However, the unique glomerular staining patterns of NAPlr and plasmin activity have also been reported in patients with other glomerular diseases in which a preceding streptococcal infection was suggested.[9]

Antibody levels to nephritis-associated protease (NAPR) are elevated in streptococcal infections (group A, C, and G) associated with glomerulonephritis but are not elevated in streptococcal infections without glomerulonephritis, whereas anti-streptolysin-O titers are elevated in both circumstances. These antibodies to NAPR persist for years and perhaps are protective against further episodes of PSGN. In a study in adults, the two most frequently identified infectious agents were streptococci (27.9%) and staphylococci (24.4%).[10]

Go to Acute Poststreptococcal Glomerulonephritis for complete information on this topic.

The causal factors that underlie AGN can be broadly divided into infectious and noninfectious groups.

Infectious

The most common infectious cause of AGN has historically been infection by Streptococcus species (ie, group A, beta-hemolytic). Two types have been described, involving different serotypes:

• Serotype 12 - Poststreptococcal nephritis due to an upper respiratory infection, occurring primarily in the winter months

• Serotype 49 - Poststreptococcal nephritis due to a skin infection, usually observed in the summer and fall and more prevalent in southern regions of the United States

PSGN usually develops 1-3 weeks after acute infection with specific nephritogenic strains of group A beta-hemolytic streptococcus. The incidence of glomerulonephritis is approximately 5-10% in persons with pharyngitis and 25% in those with skin infections.

Nonstreptococcal postinfectious glomerulonephritis may also result from infection by other bacteria, viruses, parasites, or fungi. Bacteria other than group A streptococci that can cause AGN include the following:

• Staphylococci
• Diplococci
• Other streptococci
• Mycobacteria
• Salmonella typhosa
• Brucella suis
• Treponema pallidum
• Corynebacterium bovis
• Actinobacilli

Cytomegalovirus (CMV), coxsackievirus, Epstein-Barr virus (EBV), hepatitis B virus (HBV),[11] rubella, rickettsiae (as in scrub typhus), parvovirus B19,[12] and mumps virus are accepted as viral causes only if it can be documented that a recent group A beta-hemolytic streptococcal infection did not occur. AGN has been documented as a rare complication of hepatitis A.[13]

Attributing glomerulonephritis to a parasitic or fungal etiology also requires the exclusion of a streptococcal infection. Identified organisms include Coccidioides immitis and the following parasites:

• Plasmodium malariae
• Plasmodium falciparum
• Schistosoma mansoni
• Toxoplasma gondii
• Wuchereria bancrofti
• Trichinella roundworms
• Trypanosomes

Noninfectious

Noninfectious causes of AGN may be divided into primary kidney diseases, systemic diseases, and miscellaneous conditions or agents.

Multisystem systemic diseases that can cause acute GN include the following:

• Vasculitis (eg, granulomatosis with polyangiitis [Wegener granulomatosis]) - This causes glomerulonephritis that combines upper and lower granulomatous nephritides).

• Collagen-vascular diseases (eg, systemic lupus erythematosus [SLE]) – This causes glomerulonephritis through renal deposition of immune complexes).

• Hypersensitivity vasculitis – This encompasses a heterogeneous group of disorders featuring small vessel and skin disease.

• Cryoglobulinemia – This causes abnormal quantities of cryoglobulin in plasma that result in repeated episodes of widespread purpura and cutaneous ulcerations upon crystallization.

• Polyarteritis nodosa - This causes nephritis from a vasculitis involving the renal arteries.

• Henoch-Schönlein purpura – This causes a generalized vasculitis resulting in glomerulonephritis.

• Goodpasture syndrome – This causes circulating antibodies to type IV collagen and often results in a rapidly progressive oliguric renal failure (weeks to months).

Primary renal diseases that can cause AGN include the following:

• Membranoproliferative glomerulonephritis (MPGN) - This is due to the expansion and proliferation of mesangial cells as a consequence of the deposition of complements. Type I refers to the granular deposition of C3; type II refers to an irregular process.

• Immunoglobulin A (IgA) nephropathy (Berger disease) - This causes glomerulonephritis as a result of diffuse mesangial deposition of IgA and IgG.

• “Pure” mesangial proliferative glomerulonephritis[7]

• Idiopathic rapidly progressive glomerulonephritis - This form of glomerulonephritis is characterized by the presence of glomerular crescents. Three types have been distinguished: Type I is an antiglomerular basement membrane disease, type II is mediated by immune complexes, and type III is identified by antineutrophil cytoplasmic antibody (ANCA).

Miscellaneous noninfectious causes of acute GN include the following:

• Guillain-Barré syndrome
• Irradiation of Wilms tumor
• Diphtheria-pertussis-tetanus (DPT) vaccine
• Serum sickness
• Epidermal growth factor receptor activation, ^[14] and possibly its inhibition by cetuximab ^[15]
• COVID-19 vaccine ^{[16, 17]}

United States statistics

Glomerulonephritis represents 10-15% of glomerular diseases. Variable incidence has been reported, in part because of the subclinical nature of the disease in more than half the affected population. Despite sporadic outbreaks, the incidence of PSGN has fallen over the past few decades. Factors responsible for this decline may include better health care delivery and improved socioeconomic conditions.

Glomerulonephritis comprises 25-30% of all cases of end-stage renal disease (ESRD). About one fourth of patients present with acute nephritic syndrome. Most cases that progress do so relatively quickly, and ESRD may occur within weeks or months of the onset of acute nephritic syndrome. Asymptomatic episodes of PSGN exceed symptomatic episodes by a ratio of 3-4:1.

International statistics

Worldwide, IgA nephropathy (Berger disease) is the most common cause of glomerulonephritis.

With some exceptions, the incidence of PSGN has fallen in most developed countries. Japanese researchers reported that the  incidence of postinfectious glomerulonephritis in their country peaked in the 1990s, and that PSGN, which accounted for almost all of the postinfectious glomerulonephritis cases in the 1970s, has decreased to approximately 40-50% since the 1990s, while the proportion of Staphylococcus aureus infection–related nephritis increased to 30%, and hepatitis C virus infection–associated GN also increased.[18]

PSGN remains much more common in regions such as Africa, the Caribbean, India, Pakistan, Malaysia, Papua New Guinea, and South America. In Port Harcourt, Nigeria, the incidence of AGN in children aged 3-16 years was 15.5 cases per year, with a male-to-female ratio of 1.1:1; the current incidence is not much different.[19] A study from a regional dialysis center in Ethiopia found that AGN was second only to hypovolemia as a cause of acute kidney injury that required dialysis, accoujting for approximately 22% of cases.[20]

Geographic and seasonal variations in the prevalence of PSGN are more marked for pharyngeally associated glomerulonephritis than for cutaneously associated disease.[19, 21, 22]

Age-, sex-, and race-related demographics

Postinfectious GN can occur at any age but usually develops in children. Most cases occur in patients aged 5-15 years; only 10% occur in patients older than 40 years. Outbreaks of PSGN are common in children aged 6-10 years. Acute nephritis may occur at any age, including infancy.

AGN predominantly affects males (2:1 male-to-female ratio). Postinfectious GN has no predilection for any racial or ethnic group. A higher incidence (related to poor hygiene) may be observed in some socioeconomic groups.

Most epidemic cases follow a course ending in complete patient recovery (as many as 100%). In the most commonly affected age group, pediatric patients, the reported mortality ranges from 0% to 7%.

Sporadic cases of acute nephritis often progress to a chronic form. This progression occurs in as many as 30% of adult patients and 10% of pediatric patients. Glomerulonephritis is the most common cause of chronic kidney disease (25%).

In PSGN, the long-term prognosis generally is good. More than 98% of individuals are asymptomatic after 5 years, with chronic kidney disease reported in 1-3% of cases.

Within a week or so of onset, most patients with PSGN begin to experience spontaneous resolution of fluid retention and hypertension. C3 levels may normalize within 8 weeks after the first sign of PSGN. Proteinuria may persist for 6 months and microscopic hematuria for up to 1 year after onset of nephritis.

Eventually, all urinary abnormalities should disappear, hypertension should subside, and kidney function should return to normal. In adults with PSGN, full recovery of kidney function can be expected in just over half of patients. However, prognosis is dismal in patients with underlying diabetic glomerulosclerosis. Few patients with acute nephritis develop rapidly progressive kidney failure.

Approximately 15% of patients at 3 years and 2% of patients at 7-10 years may have persistent mild proteinuria. Long-term prognosis is not necessarily benign. Some patients may develop hypertension, proteinuria, and kidney insufficiency as long as 10-40 years after the initial illness. Immunity to type M protein is type-specific, long-lasting, and protective. Repeated episodes of PSGN are therefore unusual.

The prognosis for nonstreptococcal postinfectious glomerulonephritis depends on the underlying agent, which must be identified and addressed. Generally, the prognosis is worse in patients with heavy proteinuria, severe hypertension, and significant elevations of creatinine level. Nephritis associated with methicillin-resistant Staphylococcus aureus (MRSA) and chronic infections usually resolves after treatment of the infection.

In a pooled analysis of poststaphylococcal glomerulonephritis, only 44.7% of patients achieved remission; 22.9% progressed to end-stage renal disease (ESRD) and remained dialysis-dependent, and 14.5% died. Older age and diabetes mellitus were risk factors for adverse outcomes.[2]

Other causes of AGN have outcomes varying from complete recovery to complete kidney failure. The prognosis depends on the underlying disease and the overall health of the patient. The occurrence of cardiopulmonary or neurologic complications worsens the prognosis.

Murakami and colleagues examined the clinical characteristics and pathological patterns of postinfectious glomerulonephritis in 72 HIV-infected patients. The most common infectious agent was Staphylococcus. During a median of 17 months of follow-up, pathological patterns had no significant effects on renal outcomes. Mortality occurred in 14 patients overall, and mortality rates were significantly elevated among the 28 patients with healed postinfectious glomerulonephritis.[23]

In a retrospective study of 101 patients with severe lupus and rapidly progressive glomerulonephritis and 200 lupus patient controls who were followed for a median of 4 years, rapidly progressive glomerulonephritis was associated with poorer treatment response, atrophy and fibrosis, severe renal manifestations, serious sclerotic and crescentic glomeruli lesions, severe tubulointerstitial inflammation, and prominent leukocyte infiltration. Serum creatinine levels and the proportion of crescents were the most important predictors of developing ESRD.[24]

Xu et al reported an association between elevation in plasma phosphorus levels and adverse renal outcomes in Chinese patients with glomerulonephritis. In their prospective study, each 1 mg/dL elevation in baseline phosphorus was associated with a 1.33-fold higher risk of 50% reduction in estimated GFR, ESRD, or death.[25]

Counsel patients about the need for the following measures:

• Salt restriction during the acute phase to control edema and volume-related hypertension

• Blood pressure monitoring at periodic intervals

• Ongoing long-term monitoring of patients with persistent urinary abnormalities and elevated blood pressure

• Consideration of protein restriction and angiotensin-converting enzyme (ACE) inhibitors (in patients who show evidence of persistent abnormalities or in those who develop late evidence of progressive disease)

• Early antibiotic treatment of close contacts

For patient education resources, see Acute Kidney Failure.

A thorough history should be obtained, focusing on the identification of an underlying systemic disease (if any) or recent infection. Most often, the patient with acute glomerulonephritis (AGN) is a boy, aged 2-14 years, who suddenly develops puffiness of the eyelids and facial edema in the setting of a poststreptococcal infection. The urine is dark and scanty, and the blood pressure may be elevated. Nonspecific symptoms include weakness, fever, abdominal pain, and malaise.

With AGN associated with staphylococcal infection, in contrast, the patient is likely to be a middle-aged or older man, often with diabetes mellitus.[2] The onset of glomerulonephritis may be concomitant with the infection, which may be a visceral infection (eg, pneumonia, endocarditis, osteomyelitis) or a skin infection, possibly from methicillin-resistant Staphylococcus aureus.[2, 4, 26] Hematuria is almost always present.[2]  

Ask the patient about the onset and duration of the illness. Symptom onset is usually abrupt. In acute postinfectious glomerulonephritis, a latent period of up to 3 weeks occurs before onset of symptoms. However, the latent period may vary; it is typically 1-2 weeks for postpharyngitis cases and 2-4 weeks for cases of postdermal infection (ie, pyoderma). The onset of nephritis within 1-4 days of streptococcal infection suggests preexisting kidney disease.

Identify a possible etiologic agent (eg, streptococcal throat infection [pharyngitis], skin infection [pyoderma]). Recent fever, sore throat, joint pains, hepatitis, travel, heart valve replacement, and/or intravenous drug use may be causative factors. Rheumatic fever rarely coexists with acute poststreptococcal glomerulonephritis (PSGN).

Assess the consequences of the disease process (eg, uremic symptoms). Inquire about the following:

• Loss of appetite
• Generalized itching
• Tiredness, listlessness
• Nausea
• Easy bruising, nosebleeds
• Facial swelling
• Leg edema
• Shortness of breath

Inquire about signs and symptoms of AGN, including the following:

• Hematuria - This is a universal finding, even if it is microscopic. Gross hematuria is reported in 30% of pediatric patients, often manifesting as smoky-, coffee-, or cola-colored urine.

• Oliguria

• Edema (peripheral or periorbital) - This is reported in approximately 85% of pediatric patients; edema may be mild (involving only the face) to severe, bordering on a nephrotic appearance.

• Headache - This may occur secondary to hypertension; confusion secondary to malignant hypertension may be seen in as many as 5% of patients.

• Shortness of breath or dyspnea on exertion - This may occur secondary to heart failure or pulmonary edema; it is usually uncommon, particularly in children.

• Possible flank pain secondary to stretching of the renal capsule

Ask about symptoms specific to an underlying systemic disease that can precipitate acute glomerulonephritis (see Etiology). Classic presentations include the following:

• Triad of sinusitis, pulmonary infiltrates, and nephritis, suggesting granulomatosis with polyangiitis (Wegener granulomatosis)

• Nausea and vomiting, abdominal pain, and purpura, observed with Henoch-Schönlein purpura

• Arthralgias, associated with systemic lupus erythematosus (SLE)

• Hemoptysis, occurring with Goodpasture syndrome or idiopathic progressive glomerulonephritis

• Skin rashes, observed with hypersensitivity vasculitis or SLE; also possibly due to the purpura that can occur in hypersensitivity vasculitis, cryoglobulinemia, and Henoch-Schönlein purpura

The following description does not address all of the physical findings that can be associated with the nonnephrotic features of an infectious process, kidney disorder, or systemic disease that causes AGN; to do so would be beyond the scope of this article.

Patients often have a normal physical examination and blood pressure; most frequently, however, patients present with a combination of edema, hypertension, and oliguria.

The physician should look for the following signs of fluid overload:

• Periorbital and/or pedal edema
• Edema and hypertension due to fluid overload (in 75% of patients)
• Crackles (ie, if pulmonary edema)
• Elevated jugular venous pressure
• Ascites and pleural effusion (possible)

The physician should also look for the following:

• Rash (as with vasculitis, Henoch-Schönlein purpura, or lupus nephritis)
• Pallor
• Renal angle (ie, costovertebral) fullness or tenderness, joint swelling, or tenderness
• Hematuria, either macroscopic (gross) or microscopic
• Abnormal neurologic examination or altered level of consciousness (from malignant hypertension or hypertensive encephalopathy)
• Arthritis

Other signs include the following:

• Pharyngitis
• Impetigo
• Respiratory infection
• Pulmonary hemorrhage
• Heart murmur (possibly indicative of endocarditis)
• Scarlet fever
• Weight gain
• Abdominal pain
• Anorexia
• Back pain
• Oral ulcers

Progression to sclerosis is rare in the typical patient; however, in 0.5-2% of patients with acute glomerulonephritis, the course progresses toward kidney failure, resulting in kidney death in a short period.

Abnormal urinalysis (ie, microhematuria) may persist for years. A marked decline in the glomerular filtration rate (GFR) is rare.

Pulmonary edema and hypertension may develop. Generalized anasarca and hypoalbuminemia may develop secondary to severe proteinuria.

A number of complications that result in relevant end-organ damage in the central nervous system (CNS) or the cardiopulmonary system can develop in patients who present with severe hypertension, encephalopathy, and pulmonary edema. Those complications include the following:

• Hypertensive retinopathy
• Hypertensive encephalopathy
• Rapidly progressive glomerulonephritis
• Chronic kidney disease
• Nephrotic syndrome

Urinalysis and sediment examination are crucial in the evaluation of patients with acute nephritic syndrome. Look for the following:

• Protein
• Blood
• Red blood cells (RBCs)
• White blood cells (WBCs)
• Dysmorphic RBCs
• Acanthocytes
• Cellular (ie, RBC, WBC) casts
• Granular casts
• Oval fat bodies

In some instances, marked sterile pyuria is present. The presence of RBC casts is almost pathognomonic of glomerulonephritis. Urine electrolyte, urine sodium, and fractional excretion of sodium (FENa) assays are needed to assess salt avidity.

Blood tests should include the following:

• Complete blood count (CBC)
• Blood urea nitrogen (BUN), serum creatinine, and serum electrolytes (especially serum potassium)
• Erythrocyte sedimentation rate (ESR)
• Complement levels (C3, C4, CH50)

Streptozyme testing may be useful. Imaging studies are helpful in some patients, for assessment of clinical signs suggesting extrarenal involvement or for structural evaluation of the kidneys.

Characteristic results on initial blood tests in acute glomerulonephritis include the following:

• CBC: A decrease in the hematocrit may indicate a dilutional anemia. In the setting of an infectious etiology, pleocytosis may be evident.
• Kidney function studies: BUN and and creatinine levels are elevated, indicating a degree of renal compromise. The  glomerular filtration rate (GFR) may be decreased
• Electrolytes: Potassium levels may be elevated in patients with significant renal functional impairment
• ESR: usually increased

Differentiation of low and normal serum complement levels may allow the physician to narrow the differential diagnosis. Results are not readily available to the emergency physician but may be useful to the consultant.

Low serum complement levels suggest the following systemic diseases: cryoglobulinemia, systemic lupus erythematosus (SLE), bacterial endocarditis, and shunt nephritis. Under the same conditions, kidney diseases characteristic of membranoproliferative glomerulonephritis (MPGN) or poststreptococcal glomerulonephritis (PSGN) also may be considered.

Normal serum complement levels suggest a visceral abscess, polyarteritis nodosa, Goodpasture syndrome, or Henoch-Schönlein purpura. In addition, normal complement levels suggest kidney diseases such as immune complex disease, idiopathic rapidly progressive glomerulonephritis, and immunoglobulin G (IgG) or immunoglobulin A (IgA) nephropathy.

Low C3 levels are found in almost all patients with acute poststreptococcal nephritis; C4 levels may be slightly low. Hypocomplementemia is noted in 73.9% of adult patients. Type III cryoglobulinemia may be present.

In patients with new-onset nephritis syndrome and a low C3 level, Chauvet et al report that the presence of anti–factor B autoantibodies may help distinguish new-onset PSGN from hypocomplementemic C3 glomerulopathy.[27]

If methicillin-resistant Staphylococcus aureus (MRSA) is the inciting agent, then hypocomplementemia is usually not present, but plasma immunoglobulins, especially IgA, are markedly elevated.

The urine is dark. Its specific gravity is greater than 1.020. RBCs and RBC casts are present.

Proteinuria is observed. With the qualitative estimation of proteinuria, determination of high-molecular-weight (HMW) protein (eg, fractional excretion of IgG [FEIgG]) and low-molecular-weight (LMW) protein (eg, alpha-1-microglobulin), may help predict the clinical outcome and may help in guiding steroid and immunosuppressive therapy, especially in patients with primary glomerular diseases with nephrotic syndrome.

The 24-hour urine protein excretion and creatinine clearance, though not indicated in the emergency department (ED) setting, may be helpful to document the degree of kidney dysfunction and proteinuria. With this test, it is important to remember that creatinine clearance is a “steady-state” measurement. Because of rapidly changing kidney function, the creatinine clearance may not reveal the true picture; therefore, it is better to wait until kidney function has stabilized before measuring creatinine clearance.

The streptozyme tests test includes many streptococcal antigens that are sensitive for screening but are not quantitative, such as DNAase, streptokinase, streptolysin O, and hyaluronidase.

The antistreptolysin O (ASO) titer is increased in 60-80% of patients. The increase begins in 1-3 weeks, peaks in 3-5 weeks, and returns to normal in 6 months. ASO titer is unrelated to severity, duration, or prognosis of kidney disease.

Increasing ASO titers or streptozyme titers confirm recent infection. In patients with skin infection, anti-DNAase B (ADB) titers are more sensitive than ASO titers for infection with Streptococcus.

Cultures of throat and skin lesions to rule out Streptococcus species may be obtained. Blood culture is indicated in patients with any of the following:

• Fever
• Immunosuppression
• Intravenous (IV) drug use history
• Indwelling shunts or catheters

Levels of antibody to nephritis-associated protease (NAPR) are elevated in streptococcal infections with glomerulonephritis but not in streptococcal infections without glomerulonephritis.

The antinuclear antibody test is useful for patients with acute glomerulonephritis and symptoms of underlying systemic illness, such as systemic lupus erythematosus and polyarteritis nodosa.

Other tests include the following:

• Anti-DNA antibodies
• Triglyceride levels
• Hepatitis B and C serologies
• Antineutrophil cytoplasmic antibody (ANCA)
• c-ANCA (ie, if granulomatosis with polyangiitis [Wegener granulomatosis] is suspected).

Chest radiography is needed in patients with a cough, with or without hemoptysis, to assess for granulomatosis with polyangiitis (Wegener granulomatosis), Goodpasture syndrome, and pulmonary congestion. Abdominal radiographic imaging (ie, computed tomography [CT]) is needed if visceral abscesses are suspected; also look for chest abscesses.

CT scan of the head without contrast may be necessary in any patient with malignant hypertension or altered mental status.

Bedside renal ultrasonography may be appropriate to evaluate kidney size, as well as to assess the echogenicity of the renal cortex, exclude obstruction, and determine the extent of fibrosis. A kidney size of less than 9 cm is suggestive of extensive scarring and a low likelihood of reversibility.

Echocardiography may be performed in patients with a new cardiac murmur or a positive blood culture to rule out endocarditis or a pericardial effusion.

Although acute glomerulonephritis (AGN) can be diagnosed clinically without a biopsy, in many cases kidney biopsy may have an important role in the workup of glomerulonephritis because histology guides both prognosis and therapy. Kidney biopsy may be required for definitive diagnosis, particularly in primary renal diseases. Kidney biopsy is not indicated as an emergency procedure, and it is generally not necessary for diagnosis of acute PSGN.

Candidates for biopsy are patients with an individual or family history of kidney disease and patients with an atypical presentation, including massive proteinuria, nephrotic syndrome, or a rapid rise in creatinine level without resolution.

Kidney biopsy guides the classification of glomerulonephritis into one of the five following etiologic groups[28] : 

• Immune complex–mediated glomerulonephritis (eg, lupus nephritis, IgA nephropathy, PSGN, fibrillary glomerulonephritis) 
• Antineutrophil cytoplasmic antibody (ANCA)–associated glomerulonephritis  
• Anti-glomerular basement membrane (GBM) glomerulonephritis
• Monoclonal immunoglobulin-mediated glomerulonephritis
• C3 glomerulopathy

In addition to identifying the etiology, biopsy will also determine the severity of the condition. It may also reveal the presence of other lesions that may or may not be related to the glomerulonephritis.[28]

In a study of the types and characteristics of glomerulonephritis found in patients with HIV infection, Nebuloni et al reviewed 73 kidney biopsies and found that immune complex glomerulonephritis predominated (40 cases), with mesangial proliferative and MPGN being the most common of these (10 and 8 cases, respectively).[29] The authors also reported unusual characteristics in the immune complex glomerulonephritis cases, including multiple-site deposits and frequent sclerotic tendencies.

Diffuse endocapillary proliferative changes are found. The most common histologic patterns are diffuse (72.1%), focal (12.8%), and mesangial (8.1%) proliferative glomerulonephritis in adults.[10] In postinfectious GN, the glomerulus is hypercellular with marked cellular infiltration (ie, polymorphonuclear neutrophils, monocytes) (see the images below).

Light microscopy (hematoxylin and eosin stain X 25): Photograph showing enlargement of glomerular tuft with marked decrease of urinary space and hypercellularity. The hypercellularity is due to proliferation of endogenous cells and polymorphonuclear leukocyte infiltrate. Photograph courtesy of Madeleine Moussa, MD, FRCPC, Department of Pathology, London Health Sciences Centre, London, Ontario, Canada.

Light microscopy (periodic acid-Schiff stain X 40): Photograph showing enlargement of glomerular tuft with marked decrease of urinary space and hypercellularity. The hypercellularity is due to proliferation of endogenous cells and polymorphonuclear leukocyte infiltrate. Photograph courtesy of Madeleine Moussa, MD, FRCPC, Department of Pathology, London Health Sciences Centre, London, Ontario, Canada.

Immunofluorescence may show fine, granular deposits of IgG in a “starry sky” appearance (see the first image below). In poststaphylococcal glomerulonephritis, however, dominant or codominant deposition of IgA or C3 along the glomeruli is a common feature.[2] Large subepithelial deposits may be observed on electron microscopy (see the second image below). Crescents may be observed.

Immunofluorescence (X25): Fine granular deposits of immunoglobulin G (IgG) along the basement membrane and mesangium, with "starry sky" appearance. Photograph courtesy of Madeleine Moussa, MD, FRCPC, Department of Pathology, London Health Sciences Centre, London, Ontario, Canada.

Ultrastructure (electron microscopy): Photograph showing proliferation of endothelial cells and mesangial cells and leukocyte infiltrate associated with presence of large, subepithelial, electron-dense deposits (ie, "hump") (see arrow). Photograph courtesy of Madeleine Moussa, MD, FRCPC, Department of Pathology, London Health Sciences Centre, London, Ontario, Canada.

Treatment of acute poststreptococcal glomerulonephritis (PSGN) is mainly supportive, because there is no specific therapy for renal disease. When acute glomerulonephritis (AGN) is associated with chronic infections, the underlying infections must be treated.

The expertise available in the intensive care unit may be needed for management of patients with hypertensive encephalopathy or pulmonary edema. Consultation with a nephrologist may be indicated. On an outpatient basis, kidney function, blood pressure, edema, serum albumin, and urine protein excretion rate should be monitored.

In a retrospective study from New Zealand, Wong et al examined the characteristics and treatment of acute PSGN in 27 pediatric patients and determined that the need for acute dialysis was most common among the 11 children in the study with crescentic glomerulonephritis. These authors also determined that urinary sediment abnormalities persisted in the patients with crescentic glomerulonephritis even after a mean follow-up period of 3.2 years and that the benefits of immunosuppressive therapy were unclear in these patients.[21]

Go to Emergent Management of Acute Glomerulonephritis and Acute Poststreptococcal Glomerulonephritis for complete information on these topics.

Antibiotics

Antibiotics (eg, penicillin) are used to control local symptoms and to prevent spread of infection to close contacts. Antimicrobial therapy does not appear to prevent the development of glomerulonephritis, except if given within the first 36 hours. Antibiotic treatment of close contacts of the index case may help prevent development of PSGN.

Other agents

Consider the following:

• Loop diuretics may be required in patients who are edematous and hypertensive, in order to remove excess fluid and to correct hypertension.
• Vasodilator drugs (eg, nitroprusside, nifedipine, hydralazine, diazoxide) may be used if severe hypertension or encephalopathy is present.
• Glucocorticoids and cytotoxic agents are of no value, except in severe cases of PSGN.

Sodium and fluid restriction should be advised for treatment of signs and symptoms of fluid retention (eg, edema, pulmonary edema). Protein restriction for patients with azotemia should be advised if there is no evidence of malnutrition.

Bed rest is recommended until signs of glomerular inflammation and circulatory congestion subside. Prolonged inactivity is of no benefit in the patient recovery process.

Long-term studies on children with PSGN have revealed few chronic sequelae. Results of such studies are controversial because homogeneous populations suitable for proper epidemiologic analysis have not been assembled.

Long-term studies show higher mortality rates in elderly patients, particularly those on dialysis. Patients may be predisposed to crescent formation.

The goals of pharmacotherapy are to reduce morbidity, to prevent complications, and to eradicate associated infection. Agents used include antibiotics, loop diuretics, vasodilators, and calcium channel blockers.

Class Summary

In streptococcal infections, early antibiotic therapy may prevent antibody response to exoenzymes and render throat cultures negative, but may not prevent the development of PSGN.

Penicillin V

Penicillin V is more resistant than penicillin G to hydrolysis by acidic gastric secretions and is absorbed rapidly after oral administration. 250 mg of penicillin V = 400,000 U of penicillin.

Cephalexin (Keflex)

Cephalexin is a first-generation cephalosporin that inhibits bacterial replication by inhibiting bacterial cell wall synthesis. It is bactericidal and effective against rapidly growing organisms forming cell walls.

Resistance occurs by alteration of penicillin-binding proteins. It is effective for the treatment of infections caused by streptococci or staphylococci, including penicillinase-producing staphylococci. It may bed used to initiate therapy when streptococcal or staphylococcal infection is suspected.

Cephalexin is used orally when outpatient management is indicated. It is at least as effective as erythromycin in eradicating GABHS infection.

Erythromycin (E.E.S., Ery-Tab, Erythrocin)

The recommended dosing schedule of erythromycin may result in GI upset, causing one to prescribe an alternative macrolide or to change to thrice-daily dosing. Erythromycin covers most potential etiologic agents, including mycoplasmal species.

Erythromycin is less active against H influenzae. Although 10 days seems to be a standard course of treatment, treating until the patient has been afebrile for 3-5 days seems to be a more rational approach. It inhibits bacterial growth, possibly by blocking dissociation of peptidyl tRNA from ribosomes, causing RNA-dependent protein synthesis to arrest. It is indicated for staphylococcal and streptococcal infections.

In children, age, weight, and severity of infection determine the proper dosage. When twice-daily dosing is desired, half the total daily dose may be taken every 12 hours. For more severe infections, double the dose.

Erythromycin has the added advantage of being a good anti-inflammatory agent by inhibiting the migration of polymorphonuclear leukocytes.

Oral erythromycin is an acceptable alternative for patients allergic to penicillin or cephalosporin antibiotics and is effective in the treatment of streptococcal pharyngitis. Erythromycin estolate and erythromycin ethylsuccinate are both effective, although note local antibiotic resistant rates because up to 5% of isolates of S pyogenes may be resistant to erythromycin.

Class Summary

Loop diuretics decrease plasma volume and edema by causing diuresis. The reductions in plasma volume and stroke volume associated with diuresis decrease cardiac output and, consequently, blood pressure.

Furosemide (Lasix)

Furosemide increases excretion of water by interfering with the chloride-binding cotransport system, inhibiting sodium and chloride reabsorption in the ascending loop of Henle and the distal renal tubule.

Furosemide is rapidly absorbed from the gastrointestinal (GI) tract. The diuretic effect is apparent within 1 hour of oral (PO) administration, peaks by the second hour, and lasts for 4-6 hours. After intravenous (IV) administration, diuresis occurs within 30 minutes; the duration of action is about 2 hours; 66% of the dose is excreted in the urine.

Class Summary

These agents reduce systemic vascular resistance, which, in turn, may allow forward flow, improving cardiac output.

Sodium nitroprusside (Nitropress)

Sodium nitroprusside is a potent, rapidly acting IV antihypertensive agent. Its effect is immediate and usually ends as soon as infusion is stopped because of its rapid biotransformation. Sodium nitroprusside produces vasodilation and increases inotropic activity of the heart. At higher dosages, it may exacerbate myocardial ischemia by increasing heart rate. Use this agent only for treatment of acute severe hypertension or malignant hypertension that is refractory to standard therapy.

Hydralazine

Hydralazine lowers blood pressure by exerting a peripheral vasodilating effect through direct relaxation of vascular smooth muscle. Sodium retention and excessive sympathetic stimulation of the heart may be precluded by coadministration of a thiazide diuretic and a beta-blocker.

Class Summary

In specialized conducting and automatic cells in the heart, calcium is involved in the generation of the action potential. Calcium channel blockers inhibit the movement of calcium ions across the cell membrane, depressing both impulse formation (automaticity) and conduction velocity.

Nifedipine (Afeditab CR, Nifediac, Adalat CC, Procardia, Procardia XL)

Nifedipine is a dihydropyridine calcium channel blocker. The specific mechanisms by which nifedipine reduces blood pressure have not been fully determined but are believed to be brought about largely by its vasodilatory action on peripheral blood vessels. Nifedipine relaxes coronary smooth muscle and produces coronary vasodilation, which, in turn, improves myocardial oxygen delivery.