Membranoproliferative glomerulonephritis laboratory findings
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Jogeet Singh Sekhon, M.D. [2]
Overview
MPGN laboratory findings include urinalysis, renal function tests, complete blood counts, complement profile and other diagnostic tests for evaluating the cause of MPGN.
Laboratory Findings
Urinalysis
- Glomerular hematuria; characterized by dysmorphic red blood cells (RBCs) and RBC casts[1]
- Proteinuria is almost always present.
- Urine protein creatinine ratio is a good estimate of 24-hour urinary protein excretion.
- Nephrotic proteinuria is present in approximately 50% of patients.
Serum chemistries
- Elevated serum creatinine and blood urine nitrogen and a decreased estimated glomerular filtration rate (GFR) are evident in 20-50% of patients at presentation. Patients with a nephritic presentation typically have a decreased GFR[2].
- Hyperlipidemia and low albumin may be seen with nephrotic syndrome.
CBC with differential:
- Most often, patients have a normocytic normochromic anemia
Urine analysis
- May show proteinuria
Renal function tests
- Serum creatinine and BUN might be elevated
Complement profile
- C3, C4 and CH50 levels for classic complement pathway
- AH50 levels for alternate complement pathway
- C3 nephritic factor levelsj[3]
Serum ANA
- Postive serum ANA means autoimmune disease etiology
Blood culture
- Chronic bacterial infections
Sequence of Diagnostic Studies
The urinalysis and comprehensive chemistry panel should be performed when:[4]
- The patient presented with signs of hypertension and proteinurea
- Complete blood count
- Urinaylsis
- A positive ANA, anti dsDNA suggest the diagnosis of membranous glomerulonephritis
- To confirm the diagnosis we do renal biopsy
Complement profile -
- MPGN type I[5]
- C3 levels are low in about half of the patients.
- Evidence of activation of the classic pathway of complement (ie, low C4, C2, C1q, B, C3)
- Terminal complement components C3, C5, C8, and C9 may be low or within the reference range.
- NFc (C4NeF) or NFt may be present.
- MPGN type II
- C3 levels are low in 70-80% of patients.
- Early and terminal complement components are within the reference range.
- NFa (C3NeF) is present in more than 70% of patients.
- MPGN type III
- C3 levels are decreased in 50% of patients.
- C1q and C4 levels are within the reference range.
- Terminal complement components are low, especially if C3 is markedly depressed.
- NFa is absent and NFt is present in 60-80% of patients.
- Antistreptolysin-O (ASO) titers may be elevated in as many as 50% of patients at presentation.
- To rule out secondary causes, obtain antinuclear antibodies, hepatitis screens, cryoglobulins, urine, and serum protein electrophoresis.
References
- ↑ Sethi S, Fervenza FC (2012). "Membranoproliferative glomerulonephritis--a new look at an old entity". N Engl J Med. 366 (12): 1119–31. doi:10.1056/NEJMra1108178. PMID 22435371.
- ↑ Rennke HG (1995). "Secondary membranoproliferative glomerulonephritis". Kidney Int. 47 (2): 643–56. PMID 7723253.
- ↑ Bourke E, Campbell WG, Piper M, Check IJ (1989). "Hypocomplementemic proliferative glomerulonephritis with C3 nephritic-factor-like activity in multiple myeloma". Nephron. 52 (3): 231–7. doi:10.1159/000185648. PMID 2662048.
- ↑ Qin W, Beck LH, Zeng C, Chen Z, Li S, Zuo K, Salant DJ, Liu Z (June 2011). "Anti-phospholipase A2 receptor antibody in membranous nephropathy". J. Am. Soc. Nephrol. 22 (6): 1137–43. doi:10.1681/ASN.2010090967. PMC 3103733. PMID 21566055.
- ↑ Alpers CE, Smith KD (2008). "Cryoglobulinemia and renal disease". Curr Opin Nephrol Hypertens. 17 (3): 243–9. doi:10.1097/MNH.0b013e3282f8afe2. PMID 18408474.