Post-infectious glomerulonephritis is a type of glomerulonephritis, and thus an important cause of nephritic syndrome. It predominantly occurs in children and is a sequela of streptococcal throat or skin infections. The implicated organism is almost always, group A streptococcus.
Children older than 3 years are the most susceptible to post-infectious glomerulonephritis (PIGN), with boys affected twice as much as girls. A history of throat infection, tonsillitis or strep throat, for example, about 1 to 2 weeks prior to presentation, or up to 6 weeks in the case of suppurative skin infections such as impetigo, is always present. Only nephritogenic variants of group A streptococcus (GAS) can lead to PIGN . Patients may not always have a record of treatment, as symptoms may have been mild, or resolved quickly, not warranting a hospital visit. Non-specific symptoms seen include tiredness, gastrointestinal upset (nausea, vomiting, abdominal pain), loss of appetite and malaise. Fever is not a common finding and its presence should alert the clinician of ongoing infection.
The usual presenting complaints are some or all of the symptoms characterizing nephritic syndrome namely gross hematuria often described as cola or tea colored urine, microscopic hematuria, hypertension, periorbital edema, and markedly decreased urine output. In some patients, the only sign of the disease is microscopic hematuria; in endemic areas, this alone should raise the suspicion of PIGN .
Hypertension and fluid overload can lead to further morbidity; acute confusion, lethargy, seizures, shortness of breath and coughing with or without hemoptysis are amongst the findings  . These may indicate the presence of encephalopathy, heart failure or pulmonary-renal syndrome . Other complications include uremia, thrombotic microangiopathy, and nephrotic syndrome after PIGN has been adequately treated . Complications such as these are considerably more frequent in adults than in children. The elderly, diabetics and alcoholics are at an increased risk of developing PIGN.
A family history of PIGN, especially among siblings, should be inquired about, as this increases the likelihood of the diagnosis by at least 10% . A preceding streptococcal infection is imperative to the diagnosis of PIGN; this might be evident in the patient history. However, in cases where it is unclear, the following laboratory tests are carried out, as they provide evidence of said infection:
Testing for renal functions may reveal elevated levels of urea and creatinine. Urinalysis is particularly useful and may show white blood cells, microscopic hematuria, red cell casts, epithelial cells as well as hyaline casts. Proteinuria is rarely present, and even when present, it is rarely in the nephrotic range. Imaging studies have no role in diagnosing or treating PIGN. Moreover, renal biopsy is not usually needed and is only done if an alternative diagnosis is suggested by unusual symptoms.