Laboratory Studies
Urinalysis in patients with postinfectious glomerulonephritis (PIGN) may reveal hematuria, pyuria, red blood cell casts, and proteinuria. Findings are very helpful for determining whether glomerulonephritis (GN) is primarily of a nephrotic or nephritic type.
In patients with an acute bacterial infection, the complete blood cell count (CBC) may show an elevated neutrophil count. Eosinophilia may be observed in patients with GN associated with subacute bacterial endocarditis (SBE) or a parasitic infection. Depending on the duration of disease and severity of kidney dysfunction, anemia may be observed due to chronic kidney disease.
The blood urea nitrogen (BUN) and serum creatinine levels are commonly elevated in patients with infection-related GN. However, levels may be normal early in the course of these disorders.
Hyperkalemia or evidence of metabolic acidosis may be observed in patients with chronic kidney disease.
Liver function tests in patients with hepatitis-associated GN commonly show an elevated aspartate aminotransferase level.
Rheumatoid factor results are commonly positive in patients with GN associated with bacterial endocarditis. [20]
Serum complement levels (C3, C4, CH50) levels commonly are low in patients with infection-related GN, more so in those with certain diseases. Low complement levels indicate an immune complex disease and are not necessarily diagnostic because they can be present in patients with other immune complex diseases (eg, lupus nephritis).
Hepatitis is a common cause of infection-related GN. Depending on the clinical presentation, a hepatitis serology panel (hepatitis B surface antigen, hepatitis C antibody) can be performed.
Cryoglobulins are commonly present in patients who have GN associated with hepatitis C.
HIV testing should be performed on all patients with GN and risk factors for HIV infection.
Depending on the clinical presentation, drawing blood for viral titers (cytomegalovirus, parvovirus B19, mumps, varicella, Epstein-Barr virus, Hantavirus) may be important in order to help identify the cause of the GN.
Stool for ova and parasites should be performed if the patient has been in areas endemic for diseases such as schistosomiasis or filariasis.
Depending on the clinical presentation, any of the following may be performed as part of the evaluation to help identify the cause of the GN:
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Antistreptolysin-O titer
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Antineutrophil cytoplasmic antibody assay
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Antiglomerular basement membrane antibody
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Serum protein electrophoresis
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Urine protein electrophoresis .
In appropriate clinical circumstances, peripheral blood smears to test for malaria may be helpful.
Imaging Studies
Renal ultrasound is routinely obtained in patients presenting with abnormal kidney function to help rule out obstructive causes of nephropathy, and findings demonstrate certain anatomic abnormalities. It is also useful to confirm the presence of 2 functioning kidneys prior to performing percutaneous kidney biopsy.
CT scan of the chest, abdomen, or pelvis may be indicated if visceral abscess is suggested.
A transthoracic echocardiogram should be performed if bacterial endocarditis is a possible cause. If findings are inconclusive, a transesophageal echocardiogram is indicated to help rule out valvular vegetations.
Procedures
Kidney biopsy and other biopsies may be helpful depending on the clinical presentation.
Histologic Findings
Depending on the cause, a number of different kidney lesions may be seen, as follows:
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Syphilis - Membranous or diffuse proliferative GN
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Hepatitis B - Membranous, membranoproliferative, or mesangial proliferative GN
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Hepatitis C - Membranoproliferative GN (most common), membranous GN (also seen)
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HIV - Focal segmental glomerulosclerosis (classic lesion), membranoproliferative GN or minimal change disease (less common)
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Parvovirus B19 - Focal segmental glomerulosclerosis
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Hantavirus - Mesangial GN
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Schistosomiasis - Mesangial proliferative GN, focal segmental glomerulosclerosis, membranoproliferative GN, or membranous GN
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Leishmaniasis - Mesangial or focal proliferative GN
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Hydatid - Mesangiocapillary GN, membranous GN
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Toxoplasmosis - Mesangioproliferative GN
Tables
| Bacterial | Viral | Protozoal |
|---|---|---|
| Staphyloccoccus aureus, S epidermidis, S albus | Hepatitis (A, B, C, E) | Plasmodium malariae, P falciparum, P vivax |
| Streptococcus pneumoniae, S viridans, S pyogenes | Human immunodeficiency virus | Leishmania donovani |
| Mycobacterium leprae, M tuberculosis | Epstein-Barr virus | Toxoplasma gondii |
| Treponema pallidum | Hantavirus | Trypanosoma cruzi, T bruci |
| Salmonella typhi, S paratyphi, S typhimurium | Coxsackie B | Toxocara canis |
| Leptospira species | Echovirus | Strongyloides stercoralis |
| Yersinia enterocolitica | Cytomegalovirus | |
| Neisseria meningitidis, Neisseria gonorrhoeae | Varicella zoster | Helminthic |
| Corynebacterium diphtheriae | Mumps | Schistosoma mansoni, S japonicum, S haematobium |
| Coxiella burnetti | Rubella | Wuchereria bancrofti |
| Brucella abortus | Influenza | Brugia malayi |
| Listeria monocytogenes | Dengue | Loa loa |
| Parvovirus | Onchocerca volvulus | |
| Syphilis | Trichinella spiralis | |
| SARS-CoV-2 (COVID-19) | ||
| Fungal | ||
| Histoplasma capsulatum | ||
| Candida | ||
| Coccidiodes immitis |
