Poststreptococcal Glomerulonephritis

Article Author:
Prashanth Rawla
Article Editor:
Dipesh Ludhwani
Updated:
6/26/2019 12:19:27 PM
PubMed Link:
Poststreptococcal Glomerulonephritis

Introduction

Poststreptococcal glomerulonephritis (PSGN) is characterized by rapid deterioration of kidney functions due to an inflammatory response (type III hypersensitivity reaction) following streptococcal infection. This condition results from specific strains of group A beta-hemolytic streptococci called nephrogenic streptococci. The disease affects the glomeruli and the small blood vessels of the kidneys.

PSGN most frequently presents in children 1 to 2 weeks after a sore throat, or 6 weeks after a skin infection (impetigo).[1]

When symptomatic, PSGN typically presents with features of the nephritic syndrome such as hematuria, oliguria, hypertension, and edema. Less commonly presentation can mimic nephrotic syndrome with significant proteinuria.

Etiology

Nephrogenic streptococci infection precedes PSGN, which initially affects skin or oropharynx. More recently, PSGN is associated with skin infections (impetigo) more frequently than throat infections (pharyngitis).[2][3]

Rare causes of post-infectious glomerulonephritis include other bacterial or viral infections and malaria.

Poor hygiene, overcrowding, and low socioeconomic status are important risk factors for streptococci outbreaks, and this explains the higher incidence of PSGN in the impoverished countries.

Genetic factors are expected to predispose to the condition since almost 40% of patients with PSGN gave a positive family history. There is no specific gene found to cause PSGN.

Epidemiology

Over the past three decades, PSGN incidence has significantly dropped in the developed countries; such as the United States, UK, Central Europe, and Japan. The reason for this progress is the use of antibiotic prophylaxis and the improvement of hygienic states. In these developed countries, PSGN has become more frequently seen in adult patients who suffer from chronic debilitating diseases.[4]

On the other hand, PSGN is still the most common cause of kidney injury in children in the Middle East, Africa, Australia, and worldwide. The annual incidence of new cases of PSGN in the developing countries ranges from 8.5 to 28.5 per 100000 individuals.[5] Around 97% of cases reported with PSGN live in underprivileged countries.

Clinically manifestations of PSGN are more common in males than in females with a ratio of 2:1. However; the incidence of subclinical PSGN is almost equal in both sexes. Racial factors were not found to play a role.

The disease most frequently affects children between the age of 3 and 12 (with the peak incidence between 5 to 6 years), and seniors greater than 60 years old.

Pathophysiology

The disease is immunological; representing a type III hypersensitivity reaction. The exact mechanism by which PSGN occurs is not fully determined. The body responds to nephrogenic streptococcal infection by forming immune complexes containing the streptococcal antigen with a human antibody.[6] Some theories suggest that these immune complexes become deposited in kidney glomeruli reaching through the circulation. Others claim that the condition results from an “in situ” formation of the antigen-antibody complex within the kidney glomeruli. This “In situ immune complex formation” is either due to a reaction against streptococci antigens deposited in the glomerular basement membrane or, according to other theories, due to an antibody reaction against glomerular components that cross-react with streptococcal antigen.[7]

Immune complexes formation activates complement pathway ending in the destruction of renal glomeruli.

History and Physical

Approximately 50% of children with PSGN are asymptomatic and are discovered accidentally during routine urine analysis.

Typically, patients give a history of a recent streptococcal infection such as pharyngitis, tonsillitis, or impetigo. However; some patients develop PSGN without experiencing symptoms of respiratory tract infection or pyoderma; this could result in a delay in diagnosing PSGN.[8]

The most common presenting symptom is gross hematuria as it occurs in 30 to 50% of cases with acute PSGN; patients often describe their urine as smoky, tea-colored, cola-colored, or rusty.

Oliguria occasionally presents in PSGN (usually resolves spontaneously in 1 to 2 weeks).

Puffiness of the eyelids (periorbital edema) is typical for nephritic syndrome. It is most prominent in the morning and tends to resolve at the end of the day. Generalized edema is also a common feature. Moreover, in severe cases, patients might experience respiratory distress as a result of pulmonary edema.

Patients may experience other, non-specific, symptoms like anorexia, malaise, nausea, vomiting, etc.

On examination, signs of nephritic syndrome are usually manifested such as hypertension and edema.

Evaluation

PSGN should be suspected in all children with hypertension and heart failure, even if they don’t complain of hematuria or give a history of a preceding sore throat or pyoderma.

Laboratory investigations are the most useful in PSGN assessment.

  • Evidence of a preceding streptococcal infection is determined by measuring anti-streptolysin titer (ASO), and anti-nicotinamide-adenine dinucleotidase (anti-NAD) which tend to rise following pharyngitis. Other antibodies such as anti-DNAse B and anti-hyaluronidase (AHase) are usually elevated after both pharyngitis and skin infections. ASO titer is the most frequently used test, while the most sensitive is the streptozyme test; which includes measuring the titers of all the antibodies mentioned above.
  • Serum complement levels (C3) are usually low due to its consumption in the inflammatory reaction. Mostly, the decrease in C3 concentration occurs before serum ASO has risen.[7] Complement levels usually return to normal levels in 6-8 weeks unless the case is complicated.
  • Urine analysis: shows macroscopic or microscopic hematuria, RBC casts, mild proteinuria. Only 5% of patients with PSGN have massive proteinuria that indicates nephrotic syndrome. White blood cell casts, hyaline, and cellular casts are usually present in the urine analysis.
  • Renal Function Tests: Blood urea nitrogen (BUN) and serum creatinine typically elevate during the acute phase. These values usually return to normal later.

Histologic studies:

Renal biopsy is not recommended for diagnosing patients with PSGN and is performed only when other glomerular pathologies are suspected.

  • Light microscopy: all glomeruli show hypercellularity (endothelial, mesangial, and inflammatory cells). These findings are non-specific and are present in other glomerular pathologies.
  • Electron microscopy: the most characteristic finding by electron microscopy is the presence of humps; which are electron-dense deposits in the subepithelial space near the glomerular basement membrane.[9]
  • Immunofluorescence microscopy: shows deposits of IgG and C3 if the tissue sample was taken in the first 2 to 3 weeks of the disease.

Imaging studies:

  • Ultrasonography: Kidneys are enlarged only in a few patients.

Treatment / Management

PSGN is a self-limiting condition in most cases, and thus only symptomatic treatment is needed. Supportive treatment aims at controlling the complications of volume overload such as hypertension and edema, which are prominent during the acute phase of the disease.[7]

General measures:

  • Salt and water restriction is the initial step to control edema.
  • Bed rest and immobilization are recommendations in the first few days of the disease.

Pharmacological therapy:

Loop diuretics: 1mg/kg IV furosemide (maximum 40mg) is given to control edema if dietary measures are not sufficient.

Antihypertensive medications: Angiotensin-converting enzyme inhibitors (ACEI), angiotensin receptor blockers (ARBs), or calcium channel blockers (CCBs) are given to control hypertension if the blood pressure fails to return to normal after diuresis. The first two should be given with caution in patients with impaired kidney functions due to their risk of hyperkalemia.

Antimicrobials: patients with evidence of a persistent streptococcal infection should receive a course of antibiotic therapy.

Immunosuppressive therapy: There’s no evidence that immune suppression is useful in patients with PSGN.[10]

Dialysis: 

Dialysis is only performed when potassium and creatinine levels are critically high.

Differential Diagnosis

  • IgA Nephropathy: usually occurs after an upper respiratory tract infection, but it differs from PSGN in the shorter latency period it takes to appear after the episode of infection.
  • Membranoproliferative glomerulonephritis: also presents with a nephritic picture and hypocomplementemia following respiratory tract infection. Complement levels take a longer time to return to normal than in PSGN.
  • Lupus nephritis: sometimes PSGN presents with a picture similar to lupus nephritis. Laboratory testing for antibodies specific to each of the diseases can help in the diagnosis.
  • Nephrotic syndrome

Prognosis

PSGN has an excellent prognosis especially in children with complete recovery usually occurring within 6 to 8 weeks. In adults, around 50% of the patients continue to have reduced renal function, hypertension, or persistent proteinuria.[11][12]

Complications

Complications are more likely to present in adults.  During the acute phase, congestive heart failure and azotemia are likely complications which, if not managed properly, could lead to death.

Nephrotic syndrome due to rupture of the glomerular filtration barrier and chronic renal failure are possible late complications.

Consultations

  • Nephrology
  • Interventional radiology for renal biopsy

Deterrence and Patient Education

Avoidance of overcrowding and personal hygiene are important measures that patients should undertake to decrease the risk of catching streptococcal infections.

Patients with throat or skin infections should seek medical advice and get the proper antibiotic therapy if they receive confirmation of a bacterial infection.

Enhancing Healthcare Team Outcomes

Managing a case of PSGN requires cooperation between internists, nephrologists, infectious disease consultants, pharmacists, and nursing staff to provide excellent care for their patient. PSGN patient’s fluid and salt intake, as well as urine output, should be carefully monitored. Consulting a nephrologist (or a pediatric nephrologist) must be sought in complicated cases. These patients need monitoring for fluid and electrolyte status at each visit. The prognosis in children is excellent bur adults tend to have a protracted course with at least 30 to 50% developing renal dysfunction and hypertension.[13][14](Level V)



  • (Move Mouse on Image to Enlarge)
    • Image 8614 Not availableImage 8614 Not available
      Image courtesy S Bhimji MD

References

[1] Blyth CC,Robertson PW,Rosenberg AR, Post-streptococcal glomerulonephritis in Sydney: a 16-year retrospective review. Journal of paediatrics and child health. 2007 Jun;     [PubMed PMID: 17535174]
[2] Ilyas M,Tolaymat A, Changing epidemiology of acute post-streptococcal glomerulonephritis in Northeast Florida: a comparative study. Pediatric nephrology (Berlin, Germany). 2008 Jul;     [PubMed PMID: 18373105]
[3] Hunt EAK,Somers MJG, Infection-Related Glomerulonephritis. Pediatric clinics of North America. 2019 Feb;     [PubMed PMID: 30454751]
[4] Rodriguez-Iturbe B,Haas M, Post-Streptococcal Glomerulonephritis 2016;     [PubMed PMID: 26866231]
[5] Rodriguez-Iturbe B,Musser JM, The current state of poststreptococcal glomerulonephritis. Journal of the American Society of Nephrology : JASN. 2008 Oct;     [PubMed PMID: 18667731]
[6] Balasubramanian R,Marks SD, Post-infectious glomerulonephritis. Paediatrics and international child health. 2017 Nov;     [PubMed PMID: 28891413]
[7] VanDeVoorde RG 3rd, Acute poststreptococcal glomerulonephritis: the most common acute glomerulonephritis. Pediatrics in review. 2015 Jan;     [PubMed PMID: 25554106]
[8] Pais PJ,Kump T,Greenbaum LA, Delay in diagnosis in poststreptococcal glomerulonephritis. The Journal of pediatrics. 2008 Oct;     [PubMed PMID: 18534213]
[9] "Humps" in acute nephritis. British medical journal. 1967 Apr 1     [PubMed PMID: 6021002]
[10] Roy S 3rd,Murphy WM,Arant BS Jr, Poststreptococcal crescenteric glomerulonephritis in children: comparison of quintuple therapy versus supportive care. The Journal of pediatrics. 1981 Mar;     [PubMed PMID: 7205449]
[11] Lien JW,Mathew TH,Meadows R, Acute post-streptococcal glomerulonephritis in adults: a long-term study. The Quarterly journal of medicine. 1979 Jan;     [PubMed PMID: 482595]
[12] Kasahara T,Hayakawa H,Okubo S,Okugawa T,Kabuki N,Tomizawa S,Uchiyama M, Prognosis of acute poststreptococcal glomerulonephritis (APSGN) is excellent in children, when adequately diagnosed. Pediatrics international : official journal of the Japan Pediatric Society. 2001 Aug;     [PubMed PMID: 11472580]
[13] Vachvanichsanong P,Dissaneewate P,Lim A,McNeil E, Childhood acute renal failure: 22-year experience in a university hospital in southern Thailand. Pediatrics. 2006 Sep     [PubMed PMID: 16894011]
[14] Zaffanello M,Cataldi L,Franchini M,Fanos V, Evidence-based treatment limitations prevent any therapeutic recommendation for acute poststreptococcal glomerulonephritis in children. Medical science monitor : international medical journal of experimental and clinical research. 2010 Apr     [PubMed PMID: 20357732]