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KembaraXtra-Medicine- Acute Glomerulonephritis
Acute glomerulonephritis (GN) is inflammation of the kidney glomerulus—an intricate capillary network—most often driven by an autoimmune process that causes deposition of immunoreactants and recruitment of inflammatory cells. Clinically, it typically presents with hematuria and proteinuria along with new or worsening hypertension. Without appropriate treatment, ongoing glomerular inflammation can progress to chronic kidney disease.
Acute GN is also referred to as acute nephritic syndrome (or acute GN). ICD-10-CM coding falls under the acute nephritic syndrome category (N00.0–N00.9), with codes reflecting morphologic patterns such as focal/segmental lesions, diffuse membranous disease, mesangial proliferative patterns, endocapillary proliferative GN, mesangiocapillary/MPGN patterns, dense deposit disease, crescentic GN, and unspecified morphologic changes.
Epidemiologically, the incidence of primary GN varies by subtype, with reported estimates ranging from about 0.2 per 100,000 patient-years for membranoproliferative GN to about 2.5 per 100,000 patient-years for IgA nephropathy. IgA nephropathy is the most common form worldwide. Glomerulonephritis contributes substantially to global kidney failure burden, accounting for a significant proportion of end-stage kidney disease. GN occurs in both children and adults.
Patients commonly present with acute-onset hypertension, dark “tea-colored” urine from gross hematuria, edema (periorbital, peripheral, or pulmonary), and fatigue. Certain systemic clues suggest an underlying cause: concurrent pulmonary hemorrhage with rapidly progressive renal decline suggests crescentic GN (often ANCA-associated vasculitis or anti-GBM disease). Joint pain, oral ulcers, and malar rash point toward systemic lupus erythematosus (SLE). Palpable purpura can be seen in systemic vasculitides such as IgA vasculitis, ANCA-associated vasculitis, SLE, or cryoglobulinemia. A recent history of pharyngitis, cellulitis, or endocarditis preceding urinary abnormalities raises suspicion for infection-related GN. Hepatitis C can cause membranoproliferative GN with or without cryoglobulinemia, and “synpharyngitic” gross hematuria (hematuria coinciding with an upper respiratory infection) is a classic pattern in IgA nephropathy.
Etiologically, acute GN can be kidney-limited or part of a broader systemic disorder. Understanding of mechanisms has expanded considerably. IgA nephropathy is described as a multi-hit process involving under–O-galactosylated IgA1, formation of O-glycan–specific antibodies, and deposition of IgA1-containing immune complexes in glomeruli. Hepatitis C can drive chronic immune stimulation with cryoglobulin formation and deposition. Poststreptococcal GN is now included within “infection-related GN,” which also includes IgA-dominant staphylococcal-associated GN. ANCA-associated vasculitis is linked to antibodies against myeloperoxidase and proteinase 3, though direct causation remains complex. Paraprotein-related glomerular injury can occur even without overt hematologic malignancy; when kidney injury is driven by a monoclonal immunoglobulin in that setting, it is termed monoclonal gammopathy of renal significance. C3 glomerulopathy (C3 GN and dense deposit disease) reflects dysregulation of the alternative complement pathway, and complement activation is increasingly recognized across multiple GN entities. Thrombotic microangiopathy in native kidneys results from endothelial injury triggered by drugs, autoimmune disorders, infection, or genetic causes.
The differential diagnosis for hematuria and/or proteinuria is broad and includes urinary tract infection, nephrolithiasis, urothelial malignancy, polycystic kidney disease, acute interstitial nephritis, acute tubular necrosis, nephrotic syndrome, hereditary nephritis (e.g., Alport syndrome or thin basement membrane nephropathy), and diabetic nephropathy. These should be considered alongside GN based on the clinical picture and laboratory findings.
Workup begins with laboratory testing. Urinalysis typically shows albuminuria (the predominant protein) and hematuria with dysmorphic red blood cells and/or red cell casts. Serum blood urea nitrogen and creatinine assess kidney function. Quantification of proteinuria can be done by a 24-hour urine collection or, more commonly in practice, a spot urine protein-to-creatinine ratio; proteinuria in acute GN often ranges from about 500 mg/day to 3 g/day, though nephrotic-range proteinuria can occur. If infection-related GN is suspected, streptococcal testing (e.g., Streptozyme) and antistreptolysin O (ASO) titers can be helpful; ASO typically peaks around 3 to 5 weeks and does not correlate with disease severity or prognosis. Broader serologic evaluation is guided by suspicion for systemic disease and commonly includes ANA, anti–double-stranded DNA, complement levels (C3/C4), hepatitis B and C serologies, HIV testing, ANCA (MPO and PR3), anti-GBM antibodies, cryoglobulins, rheumatoid factor, serum and urine protein electrophoresis with immunofixation, and serum free light chains. In thrombotic microangiopathy, hematocrit and platelets may be decreased, though renal-limited cases can have normal counts. Febrile patients should have blood cultures obtained.
Imaging supports evaluation and identifies complications or alternative diagnoses. A chest radiograph is important when pulmonary symptoms or opacities are present, because diffuse alveolar hemorrhage can accompany ANCA-associated vasculitis or anti-GBM (Goodpasture disease). Renal ultrasound helps exclude structural causes of hematuria/proteinuria and provides kidney size; a sagittal length below about 9 cm suggests chronic scarring and limited reversibility. Echocardiography is indicated when there is a new murmur or positive blood cultures to assess for endocarditis and to evaluate for pericardial effusion. Definitive diagnosis and classification often require kidney biopsy with light microscopy, immunofluorescence, and electron microscopy, and biopsy of other affected organs may be considered when systemic vasculitis is suspected.
Treatment is highly dependent on the specific GN subtype and severity and should be directed with urgent nephrology involvement, especially when there is azotemia, hyperkalemia, or metabolic acidosis. Supportive nonpharmacologic measures include a low-sodium diet (around 2 g/day) for edema or hypertension and avoiding high-potassium foods when hyperkalemia is present. Acute management frequently includes diuretics for edema or hypertension, correction of electrolyte abnormalities and metabolic acidosis, and hemodialysis for diuretic-resistant volume overload, refractory hyperkalemia, uremic symptoms, or severe acidosis. Plasma exchange for antibody removal in rapidly progressive GN or diffuse alveolar hemorrhage is no longer a routine evidence-based standard for all such cases, but it may be considered selectively depending on the clinical scenario and underlying diagnosis.
Chronic management focuses on monitoring for relapse or progression and mitigating long-term complications. Many GN types may follow a relapsing-remitting course, so periodic monitoring of blood pressure, urinalysis, renal function (creatinine/BUN), serum albumin, and urine protein-to-creatinine ratio is important. ACE inhibitors or ARBs are commonly used to reduce proteinuria when not contraindicated. Lipid management with statins (and fibrates when indicated) is important, particularly when nephrotic-range proteinuria or dyslipidemia is present. Patients receiving immunosuppression require monitoring for infection, cytopenias, bone loss, gastrointestinal ulcers, hypertension, and malignancy risk, along with routine preventive care and vaccination per CDC guidance for chronic kidney disease and immunocompromised states; live vaccines are contraindicated during active immunosuppressive therapy.
Prognosis correlates strongly with initial kidney function (serum creatinine/eGFR) and the degree of chronic damage and fibrosis on kidney biopsy. Outcomes are generally worse in patients with heavy albuminuria/proteinuria, low GFR at presentation, severe hypertension, and biopsy-proven crescentic GN with a high proportion of crescents. Nephrology consultation is recommended for all suspected GN, and urgent consultation is warranted when hyperkalemia, acidosis, or significant azotemia is present.
Acute glomerulonephritis (GN) is inflammation of the kidney glomerulus—an intricate capillary network—most often driven by an autoimmune process that causes deposition of immunoreactants and recruitment of inflammatory cells. Clinically, it typically presents with hematuria and proteinuria along with new or worsening hypertension. Without appropriate treatment, ongoing glomerular inflammation can progress to chronic kidney disease.
Acute GN is also referred to as acute nephritic syndrome (or acute GN). ICD-10-CM coding falls under the acute nephritic syndrome category (N00.0–N00.9), with codes reflecting morphologic patterns such as focal/segmental lesions, diffuse membranous disease, mesangial proliferative patterns, endocapillary proliferative GN, mesangiocapillary/MPGN patterns, dense deposit disease, crescentic GN, and unspecified morphologic changes.
Epidemiologically, the incidence of primary GN varies by subtype, with reported estimates ranging from about 0.2 per 100,000 patient-years for membranoproliferative GN to about 2.5 per 100,000 patient-years for IgA nephropathy. IgA nephropathy is the most common form worldwide. Glomerulonephritis contributes substantially to global kidney failure burden, accounting for a significant proportion of end-stage kidney disease. GN occurs in both children and adults.
Patients commonly present with acute-onset hypertension, dark “tea-colored” urine from gross hematuria, edema (periorbital, peripheral, or pulmonary), and fatigue. Certain systemic clues suggest an underlying cause: concurrent pulmonary hemorrhage with rapidly progressive renal decline suggests crescentic GN (often ANCA-associated vasculitis or anti-GBM disease). Joint pain, oral ulcers, and malar rash point toward systemic lupus erythematosus (SLE). Palpable purpura can be seen in systemic vasculitides such as IgA vasculitis, ANCA-associated vasculitis, SLE, or cryoglobulinemia. A recent history of pharyngitis, cellulitis, or endocarditis preceding urinary abnormalities raises suspicion for infection-related GN. Hepatitis C can cause membranoproliferative GN with or without cryoglobulinemia, and “synpharyngitic” gross hematuria (hematuria coinciding with an upper respiratory infection) is a classic pattern in IgA nephropathy.
Etiologically, acute GN can be kidney-limited or part of a broader systemic disorder. Understanding of mechanisms has expanded considerably. IgA nephropathy is described as a multi-hit process involving under–O-galactosylated IgA1, formation of O-glycan–specific antibodies, and deposition of IgA1-containing immune complexes in glomeruli. Hepatitis C can drive chronic immune stimulation with cryoglobulin formation and deposition. Poststreptococcal GN is now included within “infection-related GN,” which also includes IgA-dominant staphylococcal-associated GN. ANCA-associated vasculitis is linked to antibodies against myeloperoxidase and proteinase 3, though direct causation remains complex. Paraprotein-related glomerular injury can occur even without overt hematologic malignancy; when kidney injury is driven by a monoclonal immunoglobulin in that setting, it is termed monoclonal gammopathy of renal significance. C3 glomerulopathy (C3 GN and dense deposit disease) reflects dysregulation of the alternative complement pathway, and complement activation is increasingly recognized across multiple GN entities. Thrombotic microangiopathy in native kidneys results from endothelial injury triggered by drugs, autoimmune disorders, infection, or genetic causes.
The differential diagnosis for hematuria and/or proteinuria is broad and includes urinary tract infection, nephrolithiasis, urothelial malignancy, polycystic kidney disease, acute interstitial nephritis, acute tubular necrosis, nephrotic syndrome, hereditary nephritis (e.g., Alport syndrome or thin basement membrane nephropathy), and diabetic nephropathy. These should be considered alongside GN based on the clinical picture and laboratory findings.
Workup begins with laboratory testing. Urinalysis typically shows albuminuria (the predominant protein) and hematuria with dysmorphic red blood cells and/or red cell casts. Serum blood urea nitrogen and creatinine assess kidney function. Quantification of proteinuria can be done by a 24-hour urine collection or, more commonly in practice, a spot urine protein-to-creatinine ratio; proteinuria in acute GN often ranges from about 500 mg/day to 3 g/day, though nephrotic-range proteinuria can occur. If infection-related GN is suspected, streptococcal testing (e.g., Streptozyme) and antistreptolysin O (ASO) titers can be helpful; ASO typically peaks around 3 to 5 weeks and does not correlate with disease severity or prognosis. Broader serologic evaluation is guided by suspicion for systemic disease and commonly includes ANA, anti–double-stranded DNA, complement levels (C3/C4), hepatitis B and C serologies, HIV testing, ANCA (MPO and PR3), anti-GBM antibodies, cryoglobulins, rheumatoid factor, serum and urine protein electrophoresis with immunofixation, and serum free light chains. In thrombotic microangiopathy, hematocrit and platelets may be decreased, though renal-limited cases can have normal counts. Febrile patients should have blood cultures obtained.
Imaging supports evaluation and identifies complications or alternative diagnoses. A chest radiograph is important when pulmonary symptoms or opacities are present, because diffuse alveolar hemorrhage can accompany ANCA-associated vasculitis or anti-GBM (Goodpasture disease). Renal ultrasound helps exclude structural causes of hematuria/proteinuria and provides kidney size; a sagittal length below about 9 cm suggests chronic scarring and limited reversibility. Echocardiography is indicated when there is a new murmur or positive blood cultures to assess for endocarditis and to evaluate for pericardial effusion. Definitive diagnosis and classification often require kidney biopsy with light microscopy, immunofluorescence, and electron microscopy, and biopsy of other affected organs may be considered when systemic vasculitis is suspected.
Treatment is highly dependent on the specific GN subtype and severity and should be directed with urgent nephrology involvement, especially when there is azotemia, hyperkalemia, or metabolic acidosis. Supportive nonpharmacologic measures include a low-sodium diet (around 2 g/day) for edema or hypertension and avoiding high-potassium foods when hyperkalemia is present. Acute management frequently includes diuretics for edema or hypertension, correction of electrolyte abnormalities and metabolic acidosis, and hemodialysis for diuretic-resistant volume overload, refractory hyperkalemia, uremic symptoms, or severe acidosis. Plasma exchange for antibody removal in rapidly progressive GN or diffuse alveolar hemorrhage is no longer a routine evidence-based standard for all such cases, but it may be considered selectively depending on the clinical scenario and underlying diagnosis.
Chronic management focuses on monitoring for relapse or progression and mitigating long-term complications. Many GN types may follow a relapsing-remitting course, so periodic monitoring of blood pressure, urinalysis, renal function (creatinine/BUN), serum albumin, and urine protein-to-creatinine ratio is important. ACE inhibitors or ARBs are commonly used to reduce proteinuria when not contraindicated. Lipid management with statins (and fibrates when indicated) is important, particularly when nephrotic-range proteinuria or dyslipidemia is present. Patients receiving immunosuppression require monitoring for infection, cytopenias, bone loss, gastrointestinal ulcers, hypertension, and malignancy risk, along with routine preventive care and vaccination per CDC guidance for chronic kidney disease and immunocompromised states; live vaccines are contraindicated during active immunosuppressive therapy.
Prognosis correlates strongly with initial kidney function (serum creatinine/eGFR) and the degree of chronic damage and fibrosis on kidney biopsy. Outcomes are generally worse in patients with heavy albuminuria/proteinuria, low GFR at presentation, severe hypertension, and biopsy-proven crescentic GN with a high proportion of crescents. Nephrology consultation is recommended for all suspected GN, and urgent consultation is warranted when hyperkalemia, acidosis, or significant azotemia is present.
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