Differentials
Systemic lupus erythematosus
SIGNS / SYMPTOMS
May have a history of lupus. History and physical examination findings that could suggest lupus include rash, photosensitivity, hair loss, oral ulcers, and arthritis.
INVESTIGATIONS
In lupus nephritis, antinuclear antibody (ANA) and anti-double stranded DNA are often elevated, and C3 and C4 often suppressed.[29] Renal biopsy shows immune complex deposition in a granular pattern.
Granulomatosis with polyangiitis (Wegener)
SIGNS / SYMPTOMS
Typically have upper airway symptoms, such as a history of sinusitis or chronic cough.
INVESTIGATIONS
Antineutrophil cytoplasmic antibody (ANCA) is elevated in granulomatosis with polyangiitis but can also be positive in antiglomerular basement membrane (anti-GBM) disease. Renal biopsy shows no immune complex deposition.[5]
Microscopic polyangiitis
SIGNS / SYMPTOMS
None.
INVESTIGATIONS
Antineutrophil cytoplasmic antibody (ANCA) is elevated in microscopic polyangiitis but can also be positive in antiglomerular basement membrane (anti-GBM) disease. Renal biopsy shows no immune complex deposition.[5]
Eosinophilic granulomatosis with polyangiitis
SIGNS / SYMPTOMS
Typically have a history of asthma and atopic or allergic symptoms.
INVESTIGATIONS
Antineutrophil cytoplasmic antibody (ANCA) is elevated in Churg-Strauss, but can also be positive in antiglomerular basement membrane (anti-GBM) disease. Renal biopsy shows no immune complex deposition.[5]
Glomerulonephritis (poststreptococcal)
SIGNS / SYMPTOMS
Presents with only glomerulonephritis. Not a cause of pulmonary-renal syndrome.
INVESTIGATIONS
Antistreptolysin O is typically elevated. C3 is typically depressed. Renal biopsy shows immune complex deposition in a granular pattern.
Bacterial endocarditis with associated immune complex glomerulonephritis
SIGNS / SYMPTOMS
May have fevers, chills, and a heart murmur.
INVESTIGATIONS
Positive blood cultures and vegetations seen on echo are diagnostic of endocarditis. Renal biopsy will show immune complex deposition.[5]
Cryoglobulinemia
SIGNS / SYMPTOMS
May have hepatitis C, lymphoproliferative disorder, underlying autoimmune disease. Symptoms may include arthralgia and cutaneous vasculitis lesions.
INVESTIGATIONS
Positive cryoglobulins.
Hepatitis B
SIGNS / SYMPTOMS
May have jaundice or history of exposure.
INVESTIGATIONS
Positive hepatitis serologies and abnormal LFTs.
Hepatitis C
SIGNS / SYMPTOMS
May have jaundice or history of exposure.
INVESTIGATIONS
Positive hepatitis serologies and abnormal LFTs.
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